 |
|
| Woodturning (rec.crafts.woodturning) To discuss tools, techniques, styles, materials, shows and competitions, education and educational materials related to woodturning. All skill levels are welcome, from art turners to production turners, beginners to masters. |
| Reply |
|
|
|
LinkBack | Thread Tools | Display Modes |
|
#1
|
|||
|
|||
Got The Chuck & Fear For My Bearings
PIcked up the SuperNova2 and the Pin Jaws. Cleaned them
up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. |
|
#2
|
|||
|
|||
|
What's with all this worry about the Jet mini's bearings? You can replace
them if they go out for a small sum and it's not a terribly big job I hear. I bought a Supernova to use on my Jet mini. (I don't think it weighs quite 8 lbs. though.) A Supernova or a Talon might be a better match for your lathe. Anyway, when I got through reading the manual that came with the chuck, I was afraid to turn the danged lathe on. Then I figured, the manual must have been written by their attorney(s), so they would be able to say that any incident that might possibly happen must have been a failure caused by excessive speed. Corporate liability, I think they call it. Well, I decided to go ahead and use the chuck sensibly at whatever speeds I felt were necessary. I've had my Jet mini and Supernova chuck for about 4 years and neither has caused me any trouble. I have turned a number of 9 1/4" bowls and I'm still on the original bearings. Pin jaws? What about the 2" standard jaws? I use them at least 75% of the time. Go ahead and enjoy your new chuck and your lathe. If the stress from worrying about excessive RPM's and bearing loads gets to be too much, you can always trade up to a Oneway 2436 or a Stubby. Barry PS Go easy on the speed. Don't try to turn too fast. An awful lot of turning can be done below 1200 RPM's. Sandpaper cuts better and doesn't burn your fingers as quickly. Tool edges don't get as hot. And centrifugal forces on bearings are less. "charlie b" wrote in message ... PIcked up the SuperNova2 and the Pin Jaws. Cleaned them up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. |
|
#3
|
|||
|
|||
|
Charlie,
Don't be too scared of teh skew, exsecially planing with teh long point down. Here is why: You have MOREW control, the tool is closer to the axix of the lathe which makes it easier to direct...it IS more like an extesion of your arm this way. I've been lucky enough to talk with both turners you mention and see them demonstrating. I find it great to hear your comments about Mike darlow as I fully agree; there is a place for mor details explanations. Unfortunately, many find this too difficult (or don't want to try and understand it). Richard Raffan sure knows his stuff (comes from doing so much production turning in his early days). Finally, until you try using the skew long point diwn, you'll never appreciate how much more control you have. From my brief experience, you are more likely to get into trouble if you are too cautious..you have to use some force or the wood WILL catch minimally and generate a bigger catch (and trouble). safe turning, Alan On Mon, 05 Sep 2005 17:43:49 -0700, charlie b wrote: PIcked up the SuperNova2 and the Pin Jaws. Cleaned them up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. |
|
#4
|
|||
|
|||
|
charlie b wrote:
PIcked up the SuperNova2 and the Pin Jaws. Cleaned them up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. The lawyers are probably setting the RPM's at 680. When I got my first Nova chuck I think it said 800. I have the original Nova and the Supernova. I run both up to 2500 rpm. Me thinks they may be worried about the liability of you getting smacked by a piece of wood if it comes off. I've had several pieces come off at all speeds and the most they ever did was drop down and spin on the floor a bit. For the slow RPM is safer crowd - aside from bowls coming apart, and they come apart at all speeds, the catches are bigger and nastier at slow speed, the cuts are rougher at slow speed, etc. Crank it up to where you are comfortable and enjoy, and the wood can tolerate - don't try spinning poor or out of balance wood at 2500! If 500 is the max you feel good at, then run at 500. I typically rough around 500 and keep bumping the speed up as it smoothes out until I am in the 1500-2000 range. Pieces are finished by the tool, I rarely have to sand anything. You mention Raffan, ever notice how fast (my guess is 2500+) his lathe is spinning? Notice he uses a variety of chucks? Notice he only gives a swipe with the paper and calls it done? Practice with the skew. It's my favorite and can be your favorite too. Just takes lots of practice, and speed. Slower RPMs seem to be the nemisis of the skew, at least for me. -- Bill Berglin "Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, 'WOW! What A RIDE!!" ... Unknown |
|
#5
|
|||
|
|||
|
charlie b wrote:
PIcked up the SuperNova2 and the Pin Jaws. Cleaned them up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. The lawyers are probably setting the RPM's at 680. When I got my first Nova chuck I think it said 800. I have the original Nova and the Supernova. I run both up to 2500 rpm. Me thinks they may be worried about the liability of you getting smacked by a piece of wood if it comes off. I've had several pieces come off at all speeds and the most they ever did was drop down and spin on the floor a bit. For the slow RPM is safer crowd - aside from bowls coming apart, and they come apart at all speeds, the catches are bigger and nastier at slow speed, the cuts are rougher at slow speed, etc. Crank it up to where you are comfortable and enjoy, and the wood can tolerate - don't try spinning poor or out of balance wood at 2500! If 500 is the max you feel good at, then run at 500. I typically rough around 500 and keep bumping the speed up as it smoothes out until I am in the 1500-2000 range. Pieces are finished by the tool, I rarely have to sand anything. You mention Raffan, ever notice how fast (my guess is 2500+) his lathe is spinning? Notice he uses a variety of chucks? Notice he only gives a swipe with the paper and calls it done? Practice with the skew. It's my favorite and can be your favorite too. Just takes lots of practice, and speed. Slower RPMs seem to be the nemisis of the skew, at least for me. -- Bill Berglin "Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, 'WOW! What A RIDE!!" ... Unknown |
|
#6
|
|||
|
|||
|
charlie b wrote:
PIcked up the SuperNova2 and the Pin Jaws. Cleaned them up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. The lawyers are probably setting the RPM's at 680. When I got my first Nova chuck I think it said 800. I have the original Nova and the Supernova. I run both up to 2500 rpm. Me thinks they may be worried about the liability of you getting smacked by a piece of wood if it comes off. I've had several pieces come off at all speeds and the most they ever did was drop down and spin on the floor a bit. For the slow RPM is safer crowd - aside from bowls coming apart, and they come apart at all speeds, the catches are bigger and nastier at slow speed, the cuts are rougher at slow speed, etc. Crank it up to where you are comfortable and enjoy, and the wood can tolerate - don't try spinning poor or out of balance wood at 2500! If 500 is the max you feel good at, then run at 500. I typically rough around 500 and keep bumping the speed up as it smoothes out until I am in the 1500-2000 range. Pieces are finished by the tool, I rarely have to sand anything. You mention Raffan, ever notice how fast (my guess is 2500+) his lathe is spinning? Notice he uses a variety of chucks? Notice he only gives a swipe with the paper and calls it done? Practice with the skew. It's my favorite and can be your favorite too. Just takes lots of practice, and speed. Slower RPMs seem to be the nemisis of the skew, at least for me. -- Bill Berglin "Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, 'WOW! What A RIDE!!" ... Unknown |
|
#7
|
|||
|
|||
|
Bill B wrote:
charlie b wrote: PIcked up the SuperNova2 and the Pin Jaws. Cleaned them up put the chuck on the JET midi lathe and now I'm concerned about my drive head bearings. This is NOT a delicate little thing - but rather an 8+ pound, 3 3/4" diameter, 2 " thick chunk of steel - without the jaws. And its center line is sitting 2 1/2" from the nearest bearing. The other issue is the JAWS manual's "DO NOT EXCEED 684 RPMS" for any of the jaws. Fortunately the JET variable speed starts at 500 rpms but the slow speed seems to conflict with the general consensus that higher speeds are better than lower speeds. Was also surprised that the chuck came with no manual and a two page "instructions" sheet - AND a DVD. COOL - a DVD. But there's almost no video - four short mpeg files - but the rest is either image files or pdf files. That sucks. Have to clean up the shop of the residue of three utility shelves - 6 shelves each - and clear off the workbench before trying this puppy out. Also picked up Raffan's tape - his skew seems an extension of his arms and hands. My teeth go on edge watching him wield that skew and hog out huge quantities of wood - starting with the long point! Got one of Mike Darlow's (the author of the article Turning Tools, Spotting Design Flaws) books - The Fundamentals of Woodturning. I was trained in engineering so his explanations and illustrations of the mechanics of turning and the use of tools is something I can understand, rather than accept "do it this way because that's the way I do it and I'm an expert.". If I can understand "what and why" I can figure out "how" myself. Relaltive to furniture making, turning seems to be The Wild Wild West - a hundred ways to do things and only one or two that don't require 100-200 hours of practice with a lot of trial and error - to say nothing of the Pucker Factor. Probably should take a class DUH! Fun this turning thing. charliel b. The lawyers are probably setting the RPM's at 680. When I got my first Nova chuck I think it said 800. I have the original Nova and the Supernova. I run both up to 2500 rpm. Me thinks they may be worried about the liability of you getting smacked by a piece of wood if it comes off. I've had several pieces come off at all speeds and the most they ever did was drop down and spin on the floor a bit. For the slow RPM is safer crowd - aside from bowls coming apart, and they come apart at all speeds, the catches are bigger and nastier at slow speed, the cuts are rougher at slow speed, etc. Crank it up to where you are comfortable and enjoy, and the wood can tolerate - don't try spinning poor or out of balance wood at 2500! If 500 is the max you feel good at, then run at 500. I typically rough around 500 and keep bumping the speed up as it smoothes out until I am in the 1500-2000 range. Pieces are finished by the tool, I rarely have to sand anything. You mention Raffan, ever notice how fast (my guess is 2500+) his lathe is spinning? Notice he uses a variety of chucks? Notice he only gives a swipe with the paper and calls it done? Practice with the skew. It's my favorite and can be your favorite too. Just takes lots of practice, and speed. Slower RPMs seem to be the nemisis of the skew, at least for me. -- Bill Berglin http://home.comcast.net/~bberg100 "Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, 'WOW! What A RIDE!!" ... Unknown |
|
#8
|
|||
|
|||
|
"Bill B" wrote in message ... For the slow RPM is safer crowd - aside from bowls coming apart, and they come apart at all speeds, the catches are bigger and nastier at slow speed, the cuts are rougher at slow speed, etc. Crank it up to where you are comfortable and enjoy, and the wood can tolerate - don't try spinning poor or out of balance wood at 2500! If 500 is the max you feel good at, then run at 500. I typically rough around 500 and keep bumping the speed up as it smoothes out until I am in the 1500-2000 range. Pieces are finished by the tool, I rarely have to sand anything. You mention Raffan, ever notice how fast (my guess is 2500+) his lathe is spinning? Notice he uses a variety of chucks? Notice he only gives a swipe with the paper and calls it done? The slower is safer crowd are those of us subject to the laws of physics. |
|
#9
|
|||
|
|||
|
"Chuck" Too bad about those buggy whip factories, eh? ^^^^^^^^^^^^^^^^^^ I don't believe I ever heard of anyone in a buggy being injured for lack of an airbag. Slower IS safer. But, slower is also slower. And, none of us is going to live forever, you know. Take as many chances as you dare, until you get hurt, and then back off a little. ;-) |
|
#10
|
|||
|
|||
|
On Wed, 7 Sep 2005 06:35:28 -0400, "George" george@least wrote:
The slower is safer crowd are those of us subject to the laws of physics. Too bad about those buggy whip factories, eh? -- Chuck *#:^) chaz3913(AT)yahoo(DOT)com Anti-spam sig: please remove "NO SPAM" from e-mail address to reply. September 11, 2001 - Never Forget ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
|
#11
|
|||
|
|||
|
"Chuck" wrote in message ... On Wed, 7 Sep 2005 06:35:28 -0400, "George" george@least wrote: The slower is safer crowd are those of us subject to the laws of physics. Too bad about those buggy whip factories, eh? Too bad about people who have to try to be smart, and succeed only in being smart-alecs. Energy available to propel a loose chunk, shake the entire piece from the chuck or knock the gouge out of your hand increases with the square of velocity. Simple truth. What's pitiful as that you think it a joke. It can bite you - hard. Those who can and will think are well aware that turning is best with the least force applied by the turner. Same holds for the turning. |
|
#12
|
|||
|
|||
|
Energy available to propel a loose chunk, shake the entire piece from the chuck or knock the gouge out of your hand increases with the square of velocity. Simple truth. What's pitiful as that you think it a joke. Huh? Wouldn't that be more like Mass times velocity? (as in a proportional relationship) Maybe the square of the RPM but not the linear velocity. Steve |
|
#13
|
|||
|
|||
|
Stephen M wrote:
Energy available to propel a loose chunk, shake the entire piece from t= he chuck or knock the gouge out of your hand increases with the square of velocity. Simple truth. What's pitiful as that you think it a joke. =20 =20 =20 Huh? Wouldn't that be more like Mass times velocity? (as in a proporti= onal relationship) Maybe the square of the RPM but not the linear velocity. =20 Steve =20 =20 1/2 mv^2 =2E.or f=3Dma and you cannot push a rope... --=20 Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those=20 who have not got it.=94 George Bernard Shaw |
|
#14
|
|||
|
|||
|
Lathe speed should be set on the basis of linear velocity of the
surface weighed up against balance of the blank and integrity of the wood. There are many references that discuss what this speed (inches/second, cm/second, feet/second) should be. As diameter, and hence circumference increases, RPM must be decreased to give the same linear speed of the surface past the tool. No one that understands the above will ever simply talk in terms of RPM nor follow a table of diameter and RPM without considering other factors. If the tool is used correctly, the cutting edge has support, and should not catch. The cutting support will increase as speed increases if the turner has presented the tool correctly. From this will follow a better surface finish than if a slow speed was used for fear of a catch (eg Raffan doesn't use 6 grades of paper starting at 80 grit because he has good technique and takes advantage of using an optimum speed. He has also learned that not all timbers are alike and some are better scraped than planed but that is another topic!). If you don't get catches at modest speeds why do you get catches at optimal spreeds? The reason will usually be simple: technique can be improved or poor sharpening of tool leading to less than suitable bevel (=can't obtain required cutting edge support so you get catches). This isn't rocket science and there are enough references for anyone who is interested (yes, one must actually read, watch and learn) to improve their technique. Regarding linear velocity calculations... Circumference = 3.1416 x diameter of blank If you multiply circumference by RPM you will have a linear surface speed. eg 1000cm x 24 RPM = 24000cm/min (400cm/second) If you want to try a recommended linear surface speed, convert it to "distance units" per minute (eg ###cm/minute) and divide it by the circumference (measured in the same distance units). Example purely for explanation (NOTE; just for explanation): Linear speed = 400cm/second = 24000cm/min Circumference of job1=1000cm : speed = 24 RPM Circumference of job2=10cm : speed = 2400RPM The linear velocity in each case of the timber surfaces is the same. For safety, approach the calculated speed from the slow side, consider the balance of the blank and the integrity of the wood! Safe turning, Alan On Thu, 08 Sep 2005 09:59:21 -0400, WillR wrote: Stephen M wrote: Energy available to propel a loose chunk, shake the entire piece from the chuck or knock the gouge out of your hand increases with the square of velocity. Simple truth. What's pitiful as that you think it a joke. Huh? Wouldn't that be more like Mass times velocity? (as in a proportional relationship) Maybe the square of the RPM but not the linear velocity. Steve 1/2 mv^2 ..or f=ma and you cannot push a rope... |
|
#15
|
|||
|
|||
|
Hi Alan, Well done, thanks.
Your helpful post made me rethink some of my long held verities. I have assumed that without a sharp tool, wood cannot be turned well. Nothing, not technique, not equipment, not speed, not bevel, not hope and not even fame, can compensate for a dull tool. I've also assumed that good _turning technique etc. can make a surface that doesn't require beginning with coarser grits, but good _sanding technique doesn't allow skipping coarser sequential grits on a lesser surface. I thought there were so many variables involved in turning a chunk of wood successfully that engineers, physicists , rocket scientists and the rest of us end up turning empirically and intuititively. It seemed to me that dogmatic assertions and 'always/nevers' about any one variable were more helpful in debate than in turning. I reckoned that we all suffer catches. Good technique and tooling may keep them infrequent and small, and proper velocity may lessen the consequences, but they happen in the real world of inattention, waving gouges and hidden nails. Anyway, your discussion provoked thought, not argument. I hope you and others will expand on it. Thanks again. Turn to Safety, Arch Fortiter http://community.webtv.net/almcc/MacsMusings |
|
#16
|
|||
|
|||
|
"Alan" wrote in message ... SNIP .......... Regarding linear velocity calculations... Circumference = 3.1416 x diameter of blank If you multiply circumference by RPM you will have a linear surface speed. eg 1000cm x 24 RPM = 24000cm/min (400cm/second) If you want to try a recommended linear surface speed, convert it to "distance units" per minute (eg ###cm/minute) and divide it by the circumference (measured in the same distance units). Example purely for explanation (NOTE; just for explanation): Linear speed = 400cm/second = 24000cm/min Circumference of job1=1000cm : speed = 24 RPM Circumference of job2=10cm : speed = 2400RPM The linear velocity in each case of the timber surfaces is the same. ========================= The math is OK, BUT: In your examples, Job 2 would be practical, with a spindle about 1 1/2 inches; Job 1 is a blank over 10 feet in diameter.... anyone here have a lathe that can swing that blank?? Ken Moon Webberville, TX |
|
#17
|
|||
|
|||
|
Glad to see you checked the maths.
It was purely an example...I did say: "Example purely for explanation (NOTE; just for explanation):" so everyone could understand the numbers were just for explanation. OK, job1 is now job 1a (client had mistakenly advised the size required). Circumference of job1a=100cm : speed = 240 RPM Starting material is a blank of australian cedar from a tree felled in the spring of 1936. It is 95mm thick and has been cut to a circle ofapproximate radius 16cm. The material shows no cracks or knots and is secured to a 200mm faceplate with four short coarse screws. A shallow fruit bowl is the intended endpoint. Safe turning, Alan On Sat, 10 Sep 2005 04:56:44 GMT, "Ken Moon" wrote: "Alan" wrote in message .. . SNIP .......... Regarding linear velocity calculations... Circumference = 3.1416 x diameter of blank If you multiply circumference by RPM you will have a linear surface speed. eg 1000cm x 24 RPM = 24000cm/min (400cm/second) If you want to try a recommended linear surface speed, convert it to "distance units" per minute (eg ###cm/minute) and divide it by the circumference (measured in the same distance units). Example purely for explanation (NOTE; just for explanation): Linear speed = 400cm/second = 24000cm/min Circumference of job1=1000cm : speed = 24 RPM Circumference of job2=10cm : speed = 2400RPM The linear velocity in each case of the timber surfaces is the same. ========================= The math is OK, BUT: In your examples, Job 2 would be practical, with a spindle about 1 1/2 inches; Job 1 is a blank over 10 feet in diameter.... anyone here have a lathe that can swing that blank?? Ken Moon Webberville, TX |
|
#19
|
|||
|
|||
|
"Alan" wrote in message ... G'day Arch, I can't disagree with the points you make. My main reason for posting was to refute any suggestion that speed should always be at the low end for safety. Whilst turning at a speed too fast for a given blank is dangerous, I don't believe turning at half the optimum speed is significantly safer and I know the surface finish will probably be poorer. You haven't refuted a thing. You have demonstrated that you don't understand the laws of physics, and you have a couple of strange turning ideas beyond that. As stated, more energy is available to the turning at faster speeds. Only a dull tool cuts better at faster speed, or a tool presented to poke and rip rather than cut and peel . Sharp tools cut well at any speed when properly presented. The quality of the cut determines the quality of the surface left behind. Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity. It's the edge that cuts, and the timber that determines the energy required to do the job. Velocity beyond that required to maintain a cut is unnecessary and increases the potential for dismounts, the distance disconnecting pieces may be thrown, and turning pressure on an improperly presented tool. Do you find it more difficult to make a cut at the bottom of a bowl than at its edge? |
|
#20
|
|||
|
|||
|
I suspect that safe turning, efficient turning, elegant turning and
satisfying turning are all so inexorably bound that most of us just refer to optimum turning. Carried to an absurdity, which we never do, the safest rpm might approach zero, but it's probably not optimum. A velocity approaching the speed of light might not be optimum either, although I heard that strange things might happen. Given that there are upper velocity limits to _optimum turning any chunk of wood, are there lower velocity limits to _optimum turning that chunk also? Can you turn too slow? I had thought so, but then I know a little about the physics that purge, but not much about the laws of physics that explain our world. C' est la guerre!  Turn to Safety, Arch Fortiter http://community.webtv.net/almcc/MacsMusings |
|
#21
|
|||
|
|||
|
"George" wrote: (clip) Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity.(clip) ^^^^^^^^^^^^^^^^^^ You've really got me thinking here. I hope you will treat what I say as a thoughtful response--not as an argumentative reaction. It is certainly true that a sharp whittling knife or a very sharp carving tool will cut smoothly and cleanly at virtually zero velocity. It is also true that such finely honed edges are difficult to maintain on lathe tools. The narrower the included angle of the cutting edge, the sharper it becomes, but also the more vulnerable to wear and breakage. What velocity does for you on the lathe is permit the use of fatter cutting-edge angles, and less finely honed, longer lasting edges. Just as your demonstration that a very sharp whittling blade will cut at zero speed, I believe it would also be easy to demonstrate that a lathe tool, sharpened on an 80 or 120 grit wheel to a 60 degree angle won't cut worth a damn in a slow, hand-held cut. Yet, professional turners work with such tools all day long and achieve good results. Why? They don't have time to turn at low speeds, nor do they have time to sharpen their tools to the fine edge that a carver NEEDS. Something about the speed, momentum, inertia, or whatever, of the wood approaching the cutting edge makes it work. On a different issue relating to speed: if you try to do a job that requires "cutting air," such as a typical natural edge bowl, trying to run a too low a speed makes it very hard to keep the tool "in orbit." The tool wants to drop into the air gap, and they bounce as the wood comes around. |
|
#22
|
|||
|
|||
|
"Leo Lichtman" wrote in message ... "George" wrote: (clip) Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity.(clip) ^^^^^^^^^^^^^^^^^^ You've really got me thinking here. I hope you will treat what I say as a thoughtful response--not as an argumentative reaction. It is certainly true that a sharp whittling knife or a very sharp carving tool will cut smoothly and cleanly at virtually zero velocity. It is also true that such finely honed edges are difficult to maintain on lathe tools. The narrower the included angle of the cutting edge, the sharper it becomes, but also the more vulnerable to wear and breakage. What velocity does for you on the lathe is permit the use of fatter cutting-edge angles, and less finely honed, longer lasting edges. Just as your demonstration that a very sharp whittling blade will cut at zero speed, I believe it would also be easy to demonstrate that a lathe tool, sharpened on an 80 or 120 grit wheel to a 60 degree angle won't cut worth a damn in a slow, hand-held cut. Yet, professional turners work with such tools all day long and achieve good results. Why? They don't have time to turn at low speeds, nor do they have time to sharpen their tools to the fine edge that a carver NEEDS. Something about the speed, momentum, inertia, or whatever, of the wood approaching the cutting edge makes it work. On a different issue relating to speed: if you try to do a job that requires "cutting air," such as a typical natural edge bowl, trying to run a too low a speed makes it very hard to keep the tool "in orbit." The tool wants to drop into the air gap, and they bounce as the wood comes around. Good thinking. You've come to the conclusion that extra power - supplied in the form of increased speed, is used to compensate for a dull or dulling edge. Shouldn't be. It's a warning that it's time to renew it. You can increase object speed, but it's a compromise, as the surface gets rougher and the tool hotter. As far as cutting air or any other form of interrupted cutting, like roughing the outside of a bowl, the bounce should be your cue that you are not holding the tool properly on the rest. A lot of trouble like this comes from that "ride the bevel" folklore. Not a bit of sense pressing air. The tool should be _Anchored to the toolrest, the _Bevel guiding on available surface. Less available surface, the more you hug the rest as you _Cut until you get one. Once you have a continuous surface to reference, doesn't mean you should press the bevel to it, either. Difference in end/face grain resistance and the broadening of the distance between annual rings can get you out of round pretty quickly if you do. You need to rethink your bevel angle theory. Blunt does not equal dull. It is the edge that cuts. Scrapers, in spite of the nomenclature, can and do cut with bevel angles approaching 90 degrees. It's in how they're presented to the work. |
|
#23
|
|||
|
|||
|
"What we have here is a failure in communication".
 I think Leo referred to the angles that form the edge ("the included angle of the cutting edge") not the supporting bevel behind it, what machinists refer to as the 'cutting angle'. The old knife, cold chisel and nail analogy: The metal in a knife is harder than a nail, but it won't cut a nail, while a cold chisel of softer steel will. In life, to succeed you've got to have an angle. My (mis)understanding is that to cut wood any tool's edge must first enter the surface using a sharp edge; the cutting angle. After that it's mosty a wedging and/or shearing action. This action, of course, depends on many factors beside angles and bevels, but I convenently omit them here. I think of cutting as wedging more than shearing. To cut (wedge) along the grain, after entry the edge isn't much needed so a narrow supporting bevel can be used. To scrape (shear) across the grain the edge is needed and thus requires a wide supporting bevel. Both actions require a sharp edge (cutting angle) to get things started. Now, I'll explain rocket science. Returning to earth having explained all I know.... I tend to neglect an important edge and an important half of an edge and the tools to make them. I mean the burr on my scrapers and my burnisher. Also the flute side of my gouge edges and my gouge slip. Just a gentle reminder. Turn to Safety, Arch Fortiter http://community.webtv.net/almcc/MacsMusings |
|
#24
|
|||
|
|||
|
"George" wrote: (clip) You need to rethink your bevel angle theory. Blunt does not equal dull. It is the edge that cuts. Scrapers, in spite of the nomenclature, can and do cut with bevel angles approaching 90 degrees. It's in how they're presented to the work. ^^^^^^^^^^^^^ I was trying to question your use of very sharp carving tools and knives to prove a point with respect to turning. Let me try again: Turning tools rest on a toolrest, and when things are right, the cutting force is directed downward, so the tool can be held in place with a gentle grip. The cutting force is downward, at about 90 degrees to the tool. Carving tools and knives have the cutting force straight into the cutting edge. They're not the same. |
|
#25
|
|||
|
|||
|
G'day George,
I have to disagree with what you have presented. I'll let anyone reading the posts decide what to accept and what to dismiss. Further, I see little benefit is likely when you have to commence with sweeping unsupported statements about the poster's knowledge and lead off with a selected edit from a longer post. Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. Regards, Alan On Sat, 10 Sep 2005 09:03:16 -0400, "George" George@least wrote: "Alan" wrote in message .. . G'day Arch, I can't disagree with the points you make. My main reason for posting was to refute any suggestion that speed should always be at the low end for safety. Whilst turning at a speed too fast for a given blank is dangerous, I don't believe turning at half the optimum speed is significantly safer and I know the surface finish will probably be poorer. You haven't refuted a thing. You have demonstrated that you don't understand the laws of physics, and you have a couple of strange turning ideas beyond that. As stated, more energy is available to the turning at faster speeds. Only a dull tool cuts better at faster speed, or a tool presented to poke and rip rather than cut and peel . Sharp tools cut well at any speed when properly presented. The quality of the cut determines the quality of the surface left behind. Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity. It's the edge that cuts, and the timber that determines the energy required to do the job. Velocity beyond that required to maintain a cut is unnecessary and increases the potential for dismounts, the distance disconnecting pieces may be thrown, and turning pressure on an improperly presented tool. Do you find it more difficult to make a cut at the bottom of a bowl than at its edge? |
|
#26
|
|||
|
|||
|
He Might no be but it is fact a well sharpened tool will go where you lead
it and a blunt tool will go ehrer it can. so if the tool is sharpend correctly and presentrd correctly a clean cut is possible at low speed. Think about the old lathes BEFORE motors with speed much slower than the modern lathe (Even at what we call SLOW SPEED) yet clean finishes were the norm for experianced turners without causing significant subsurface damage (pulling the fibre as it cuts).Remember these slower speeds also have the benifit of less impact on an inapropriately presented cutting surface. Slower speeds and a light delft touch with sharp tools WILL GIVE A CLEANER CUT than not so sharp tools heavy hand and High speeds (Actually this is asking for ignificant subsurface damage (pulling the fibre as it cuts) in soft woods. Some thing to think about Alan "Alan" wrote in message ... G'day George, I have to disagree with what you have presented. I'll let anyone reading the posts decide what to accept and what to dismiss. Further, I see little benefit is likely when you have to commence with sweeping unsupported statements about the poster's knowledge and lead off with a selected edit from a longer post. Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. Regards, Alan On Sat, 10 Sep 2005 09:03:16 -0400, "George" George@least wrote: "Alan" wrote in message . .. G'day Arch, I can't disagree with the points you make. My main reason for posting was to refute any suggestion that speed should always be at the low end for safety. Whilst turning at a speed too fast for a given blank is dangerous, I don't believe turning at half the optimum speed is significantly safer and I know the surface finish will probably be poorer. You haven't refuted a thing. You have demonstrated that you don't understand the laws of physics, and you have a couple of strange turning ideas beyond that. As stated, more energy is available to the turning at faster speeds. Only a dull tool cuts better at faster speed, or a tool presented to poke and rip rather than cut and peel . Sharp tools cut well at any speed when properly presented. The quality of the cut determines the quality of the surface left behind. Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity. It's the edge that cuts, and the timber that determines the energy required to do the job. Velocity beyond that required to maintain a cut is unnecessary and increases the potential for dismounts, the distance disconnecting pieces may be thrown, and turning pressure on an improperly presented tool. Do you find it more difficult to make a cut at the bottom of a bowl than at its edge? |
|
#27
|
|||
|
|||
|
"Leo Lichtman" wrote in message ... "George" wrote: (clip) You need to rethink your bevel angle theory. Blunt does not equal dull. It is the edge that cuts. Scrapers, in spite of the nomenclature, can and do cut with bevel angles approaching 90 degrees. It's in how they're presented to the work. ^^^^^^^^^^^^^ I was trying to question your use of very sharp carving tools and knives to prove a point with respect to turning. Let me try again: Turning tools rest on a toolrest, and when things are right, the cutting force is directed downward, so the tool can be held in place with a gentle grip. The cutting force is downward, at about 90 degrees to the tool. Carving tools and knives have the cutting force straight into the cutting edge. They're not the same. I take it you don't carve? First thing I was taught was that the tool moves in two directions for the best cut. Just as in whittling, where you draw the knife across the work as you push or pull it along. Or skew a plane in flat work. Same on the lathe. Not sure why you'd want to cut at 90 degrees to the tool on a lathe. You want your edge at a nice steep skew so the rotation will bring the material along the edge as you advance it, producing the same slicing motion you use with the other tools. |
|
#28
|
|||
|
|||
|
"Alan" wrote in message ... Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). You say it yourself. A certain amount (quantum?) of energy is required to make the cut for a specific wood and orientation. I agree, it's what I said at the beginning. Are you arguing with yourself? However, the source of that energy is immaterial. Can be your elbow or the lathe. A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. Speed does not cut the fibers. the edge does. Unless and until you get this basic concept firmly implanted, you're chasing your tail. It seems you know it to be true, because you keep talking about sharper edges doing better work. Why not just go with it? It's correct. Of course, if you did, we'd be back to the same, which is that energy in excess of that required for the cut increases potential danger. The proper mindset is to sharpen the tool rather than increase the speed to compensate. I guess that's it. You know better, you just don't care to admit the corrolary. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. |
|
#29
|
|||
|
|||
|
This all started when I contended that slower isn't always better. I
never advocated fast is always better. My position has come from considering quite a good deal of written and verbalised views (including those posted in this group). A few spurious arguments seem to have been presented and I can only hope the open minds spot them. I'm uncertain why comparisons between sharp and blunt tools entered the discussion. My point was that a turner would not usually be sharpening a tool to an edge as fine as a carver's chisel and even if he did, it would be gone very quickly. What I've written about speed and finish assumes the tool is "sharp" and has a good bevel (otherwise there are too many variables). I can't comment upon the results from pole lathe craftsman, but I'd have to suspect that "Thomas Average", a backyard pole lathe turner, would struggle to get a great finish (or were there only true craftsman using pole lathes to create the work you mention?). His tools would lose the edge faster than our HSS and sharpening must have been more difficult (I fear I am widening the front to encompass sharpening technique now!). As with all of the crafts, a few people will perform better than the many if given identical equipment. I see little benefit in comparing a sharp tool at slow speed and a not so sharp tool at fast speed (whether yelled or not)..... would not sharp and fast be better than less sharp and slow?. Rather an obvious answer in both cases I would have thought. It really doesn't do anything more than find a point I certainly know we can fullly agree upon (which isn''t bad, but doesn't really advance anything). Unless someone has something new to add I'd say we may have wrung this topic out, for a while anyway. Safe turning (at whatever speed you decide upon), Alan On Mon, 12 Sep 2005 07:20:25 GMT, "." wrote: He Might no be but it is fact a well sharpened tool will go where you lead it and a blunt tool will go ehrer it can. so if the tool is sharpend correctly and presentrd correctly a clean cut is possible at low speed. Think about the old lathes BEFORE motors with speed much slower than the modern lathe (Even at what we call SLOW SPEED) yet clean finishes were the norm for experianced turners without causing significant subsurface damage (pulling the fibre as it cuts).Remember these slower speeds also have the benifit of less impact on an inapropriately presented cutting surface. Slower speeds and a light delft touch with sharp tools WILL GIVE A CLEANER CUT than not so sharp tools heavy hand and High speeds (Actually this is asking for ignificant subsurface damage (pulling the fibre as it cuts) in soft woods. Some thing to think about Alan "Alan" wrote in message .. . G'day George, I have to disagree with what you have presented. I'll let anyone reading the posts decide what to accept and what to dismiss. Further, I see little benefit is likely when you have to commence with sweeping unsupported statements about the poster's knowledge and lead off with a selected edit from a longer post. Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. Regards, Alan On Sat, 10 Sep 2005 09:03:16 -0400, "George" George@least wrote: "Alan" wrote in message ... G'day Arch, I can't disagree with the points you make. My main reason for posting was to refute any suggestion that speed should always be at the low end for safety. Whilst turning at a speed too fast for a given blank is dangerous, I don't believe turning at half the optimum speed is significantly safer and I know the surface finish will probably be poorer. You haven't refuted a thing. You have demonstrated that you don't understand the laws of physics, and you have a couple of strange turning ideas beyond that. As stated, more energy is available to the turning at faster speeds. Only a dull tool cuts better at faster speed, or a tool presented to poke and rip rather than cut and peel . Sharp tools cut well at any speed when properly presented. The quality of the cut determines the quality of the surface left behind. Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity. It's the edge that cuts, and the timber that determines the energy required to do the job. Velocity beyond that required to maintain a cut is unnecessary and increases the potential for dismounts, the distance disconnecting pieces may be thrown, and turning pressure on an improperly presented tool. Do you find it more difficult to make a cut at the bottom of a bowl than at its edge? |
|
#30
|
|||
|
|||
|
George,
George, I think you probably prefer to be contentious. Unfortunately you misinterpret or intentionally twist what is posted so you can commence another lecture to impress. The use of the term "quantum" adds nothing to everyone's understanding of the point, but does indicate a lot about you. Safe turning, or whittling, Alan On Mon, 12 Sep 2005 07:06:52 -0400, "George" George@least wrote: "Alan" wrote in message .. . Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). You say it yourself. A certain amount (quantum?) of energy is required to make the cut for a specific wood and orientation. I agree, it's what I said at the beginning. Are you arguing with yourself? However, the source of that energy is immaterial. Can be your elbow or the lathe. A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. Speed does not cut the fibers. the edge does. Unless and until you get this basic concept firmly implanted, you're chasing your tail. It seems you know it to be true, because you keep talking about sharper edges doing better work. Why not just go with it? It's correct. Of course, if you did, we'd be back to the same, which is that energy in excess of that required for the cut increases potential danger. The proper mindset is to sharpen the tool rather than increase the speed to compensate. I guess that's it. You know better, you just don't care to admit the corrolary. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. |
|
#31
|
|||
|
|||
|
"Alan" wrote in message ... This all started when I contended that slower isn't always better. But it is definitely SAFER I never advocated fast is always better. My position has come from considering quite a good deal of written and verbalised views (including those posted in this group). A few spurious arguments seem to have been presented and I can only hope the open minds spot them. I'm uncertain why comparisons between sharp and blunt tools entered the discussion. Well sharpened as opposed to something that is not well sharpened EG BLUNT My point was that a turner would not usually be sharpening a tool to an edge as fine as a carver's chisel I DO it achieves a better cut at SAFER SLOWER speeds and even if he did, it would be gone very quickly. Not with quality tools. What I've written about speed and finish assumes the tool is "sharp" and has a good bevel (otherwise there are too many variables). Another words a well sharpened tool! I can't comment upon the results from pole lathe craftsman, but I'd have to suspect that "Thomas Average", a backyard pole lathe turner, would struggle to get a great finish (or were there only true craftsman using pole lathes to create the work you mention?). Not all lathes before motors were pole lathes having used a treadle lathe with WELL SHARPENED tools I was amazed at the quality of the cut obtained the very first time I used the lathe. Here as I said "a light delft touch with sharp tools WILL GIVE A CLEANER CUT" His tools would lose the edge faster NOT necessarily so as the wood is turning slower there is less "Grinding " action on the edge as can be seen when turning wood with a high silica content on an old lathe with the tools of the time. the remain sharp for a longer time than HSS tools turning the same wood at high speed. (Much less grinding action) than our HSS and sharpening must have been more difficult (I fear I am widening the front to encompass sharpening technique now!). No I wont go into the argument of High speed grinding as opposed to low speed wet grinding. As with all of the crafts, a few people will perform better than the many if given identical equipment. I see little benefit in comparing a sharp tool at slow speed and a not so sharp tool at fast speed (whether yelled or not)..... would not sharp and fast be better than less sharp and slow?. NO that is not what the discussion is about which is Fast and less sharp Vs Slow and Very Sharpe Rather an obvious answer in both cases I would have thought. It really doesn't do anything more than find a point I certainly know we can fullly agree upon (which isn''t bad, but doesn't really advance anything). Unless someone has something new to add I'd say we may have wrung this topic out, for a while anyway. A good way to avoid saying you are wrong. Safe turning (at whatever speed you decide upon), Slower is Much safer than Faster it just takes a bit more skill in developing a lighter touch. :-)) Alan On Mon, 12 Sep 2005 07:20:25 GMT, "." wrote: He Might no be but it is fact a well sharpened tool will go where you lead it and a blunt tool will go ehrer it can. so if the tool is sharpend correctly and presentrd correctly a clean cut is possible at low speed. Think about the old lathes BEFORE motors with speed much slower than the modern lathe (Even at what we call SLOW SPEED) yet clean finishes were the norm for experianced turners without causing significant subsurface damage (pulling the fibre as it cuts).Remember these slower speeds also have the benifit of less impact on an inapropriately presented cutting surface. Slower speeds and a light delft touch with sharp tools WILL GIVE A CLEANER CUT than not so sharp tools heavy hand and High speeds (Actually this is asking for ignificant subsurface damage (pulling the fibre as it cuts) in soft woods. Some thing to think about Alan "Alan" wrote in message . .. G'day George, I have to disagree with what you have presented. I'll let anyone reading the posts decide what to accept and what to dismiss. Further, I see little benefit is likely when you have to commence with sweeping unsupported statements about the poster's knowledge and lead off with a selected edit from a longer post. Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. Regards, Alan On Sat, 10 Sep 2005 09:03:16 -0400, "George" George@least wrote: "Alan" wrote in message m... G'day Arch, I can't disagree with the points you make. My main reason for posting was to refute any suggestion that speed should always be at the low end for safety. Whilst turning at a speed too fast for a given blank is dangerous, I don't believe turning at half the optimum speed is significantly safer and I know the surface finish will probably be poorer. You haven't refuted a thing. You have demonstrated that you don't understand the laws of physics, and you have a couple of strange turning ideas beyond that. As stated, more energy is available to the turning at faster speeds. Only a dull tool cuts better at faster speed, or a tool presented to poke and rip rather than cut and peel . Sharp tools cut well at any speed when properly presented. The quality of the cut determines the quality of the surface left behind. Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity. It's the edge that cuts, and the timber that determines the energy required to do the job. Velocity beyond that required to maintain a cut is unnecessary and increases the potential for dismounts, the distance disconnecting pieces may be thrown, and turning pressure on an improperly presented tool. Do you find it more difficult to make a cut at the bottom of a bowl than at its edge? |
|
#32
|
|||
|
|||
|
"Alan" wrote in message news  George, George, I think you probably prefer to be contentious. Unfortunately you misinterpret or intentionally twist what is posted so you can commence another lecture to impress. The use of the term "quantum" adds nothing to everyone's understanding of the point, but does indicate a lot about you. Safe turning, or whittling, Alan Well said Alan. I suspect you have really hit on the fine point of it with this post......... -- Regards, M.J. (Mike) Orr www.island.net/~morr |
|
#33
|
|||
|
|||
|
For further posts, please visit alt.binaries.semantics
AlanOn Tue, 13 Sep 2005 00:16:19 GMT, "." wrote: "Alan" wrote in message .. . This all started when I contended that slower isn't always better. But it is definitely SAFER I never advocated fast is always better. My position has come from considering quite a good deal of written and verbalised views (including those posted in this group). A few spurious arguments seem to have been presented and I can only hope the open minds spot them. I'm uncertain why comparisons between sharp and blunt tools entered the discussion. Well sharpened as opposed to something that is not well sharpened EG BLUNT My point was that a turner would not usually be sharpening a tool to an edge as fine as a carver's chisel I DO it achieves a better cut at SAFER SLOWER speeds and even if he did, it would be gone very quickly. Not with quality tools. What I've written about speed and finish assumes the tool is "sharp" and has a good bevel (otherwise there are too many variables). Another words a well sharpened tool! I can't comment upon the results from pole lathe craftsman, but I'd have to suspect that "Thomas Average", a backyard pole lathe turner, would struggle to get a great finish (or were there only true craftsman using pole lathes to create the work you mention?). Not all lathes before motors were pole lathes having used a treadle lathe with WELL SHARPENED tools I was amazed at the quality of the cut obtained the very first time I used the lathe. Here as I said "a light delft touch with sharp tools WILL GIVE A CLEANER CUT" His tools would lose the edge faster NOT necessarily so as the wood is turning slower there is less "Grinding " action on the edge as can be seen when turning wood with a high silica content on an old lathe with the tools of the time. the remain sharp for a longer time than HSS tools turning the same wood at high speed. (Much less grinding action) than our HSS and sharpening must have been more difficult (I fear I am widening the front to encompass sharpening technique now!). No I wont go into the argument of High speed grinding as opposed to low speed wet grinding. As with all of the crafts, a few people will perform better than the many if given identical equipment. I see little benefit in comparing a sharp tool at slow speed and a not so sharp tool at fast speed (whether yelled or not)..... would not sharp and fast be better than less sharp and slow?. NO that is not what the discussion is about which is Fast and less sharp Vs Slow and Very Sharpe Rather an obvious answer in both cases I would have thought. It really doesn't do anything more than find a point I certainly know we can fullly agree upon (which isn''t bad, but doesn't really advance anything). Unless someone has something new to add I'd say we may have wrung this topic out, for a while anyway. A good way to avoid saying you are wrong. Safe turning (at whatever speed you decide upon), Slower is Much safer than Faster it just takes a bit more skill in developing a lighter touch. :-)) Alan On Mon, 12 Sep 2005 07:20:25 GMT, "." wrote: He Might no be but it is fact a well sharpened tool will go where you lead it and a blunt tool will go ehrer it can. so if the tool is sharpend correctly and presentrd correctly a clean cut is possible at low speed. Think about the old lathes BEFORE motors with speed much slower than the modern lathe (Even at what we call SLOW SPEED) yet clean finishes were the norm for experianced turners without causing significant subsurface damage (pulling the fibre as it cuts).Remember these slower speeds also have the benifit of less impact on an inapropriately presented cutting surface. Slower speeds and a light delft touch with sharp tools WILL GIVE A CLEANER CUT than not so sharp tools heavy hand and High speeds (Actually this is asking for ignificant subsurface damage (pulling the fibre as it cuts) in soft woods. Some thing to think about Alan "Alan" wrote in message ... G'day George, I have to disagree with what you have presented. I'll let anyone reading the posts decide what to accept and what to dismiss. Further, I see little benefit is likely when you have to commence with sweeping unsupported statements about the poster's knowledge and lead off with a selected edit from a longer post. Are you suggesting that a well sharpened tool will cut wood fibres cleanily and equally at any lathe speed? Please advise which law of physics you are relying upon that describes the energy necessary for the cut to take place? I assume it must be independent of timber's surface velocity and derive the energy from some other source (since the cutting tip of the tool is stationary). A given amount of energy is required to cut a fibre cleanly without causing significant subsurface damage (pulling the fibre as it cuts). Stop here and consider if this is correct or false in a real turning exercise rather than with one cut from a freshly sharpened carving tool. I believe it is true, others may not. Subsurface damage is harder to repair than a clean, even rippled cut so I'd opt for a speed that will more cleanly cut the fibres. Taking this to the next stage, at some velocity, the energy available will be below that necessary to cleanly cut the fibres. This follows as a logical statement if you thought the earlier statement was considered to be true. You cannot keep a "carver's" quality edge on a turning tool so any comparisons other than to compare edge sharpness of each are not really a useful example when discussing turning. Obviously a tool sharpened for carving will cut the fibres as you push. Sounds nice but take a few cuts into a piece of jarrah with the tool and it won't have such a keen edge for long. I'm unsure what was meant by, "a couple of strange turning ideas" as I doubt I would be alone with the views contained in the section of my earlier post you copied. Regards, Alan On Sat, 10 Sep 2005 09:03:16 -0400, "George" George@least wrote: "Alan" wrote in message om... G'day Arch, I can't disagree with the points you make. My main reason for posting was to refute any suggestion that speed should always be at the low end for safety. Whilst turning at a speed too fast for a given blank is dangerous, I don't believe turning at half the optimum speed is significantly safer and I know the surface finish will probably be poorer. You haven't refuted a thing. You have demonstrated that you don't understand the laws of physics, and you have a couple of strange turning ideas beyond that. As stated, more energy is available to the turning at faster speeds. Only a dull tool cuts better at faster speed, or a tool presented to poke and rip rather than cut and peel . Sharp tools cut well at any speed when properly presented. The quality of the cut determines the quality of the surface left behind. Sharpen your jackknife and whittle a bit and see if your best cut happens at higher speed - or your carving tools. See if they don't out-perform your turning tools even at near zero relative velocity. It's the edge that cuts, and the timber that determines the energy required to do the job. Velocity beyond that required to maintain a cut is unnecessary and increases the potential for dismounts, the distance disconnecting pieces may be thrown, and turning pressure on an improperly presented tool. Do you find it more difficult to make a cut at the bottom of a bowl than at its edge? |
|
#34
|
|||
|
|||
|
"." wrote in message ... "Alan" wrote in message ... This all started when I contended that slower isn't always better. But it is definitely SAFER Interesting evaluation here, http://www.woodturningplus.com/Safety/speed_kills.htm , though there are still a couple of head-scratchers. |
|
#35
|
|||
|
|||
|
"Chuck" wrote: Gotta say it: B I N G O ^^^^^^^^^^^^^^^^ Anybody named "Chuck" must know something about lathe RPM, by George. ;-) |
|
#36
|
|||
|
|||
|
On Tue, 13 Sep 2005 00:23:29 +1000, Alan
wrote: George, George, I think you probably prefer to be contentious. Unfortunately you misinterpret or intentionally twist what is posted so you can commence another lecture to impress. Gotta say it: B I N G O -- Chuck *#:^) chaz3913(AT)yahoo(DOT)com Anti-spam sig: please remove "NO SPAM" from e-mail address to reply. September 11, 2001 - Never Forget ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
|
#37
|
|||
|
|||
|
"Leo Lichtman" wrote in message ... "Chuck" wrote: Gotta say it: B I N G O ^^^^^^^^^^^^^^^^ Anybody named "Chuck" must know something about lathe RPM, by George. ;-) If only he'd show it.... |
|
#38
|
|||
|
|||
|
This thread seems to have skipped back to my earlier
post regarding RPMs vs Safety. My limited experience, specifically with a sharp skew chisel, is that at slow speed (500 rpms) I get more catches than I do at higher speed (1200 rpms) Making shearing cuts "downhill", it seems to be easier to get a smoother surface using higher rpms than lower. When cutting coves with a detail gouge I get better surfaces and smoother curves at higher rpms than at lower rpms. Still having fun getting use to turning a tool while making a cut. Guess that's a carry over from a metal lathe. Fun stuff this turning thing. Instant gratification, relatively speaking. Of course when things go to hell in a handbasket it often means significant change to the original idea or throwing the piece away and starting over. In solid wood furniture a screw up usually doesn't require starting all over. charlie b |
|
#39
|
|||
|
|||
|
"charlie b" wrote in message ... Fun stuff this turning thing. Instant gratification, relatively speaking. Of course when things go to hell in a handbasket it often means significant change to the original idea or throwing the piece away and starting over. In solid wood furniture a screw up usually doesn't require starting all over. Except when the piece is thrown hard by a high-speed tool? |
|
#40
|
|||
|
|||
|
As the lathe speed goes up, the temperature at the cutting edge goes up. At temperatures as low as 150 degrees Farenheit some woods lose up to half their strength, making them easier to cut. So at higher speeds you will get better finishes. This information comes right out of one of Mike Darlow's books. regards Kevin |
| Reply |
|
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| My lathe's spindle is too long for my new chuck | Woodturning | |||
| Teknatool Titan Chuck draft review | Woodturning | |||
| Runout on 3 Jaw Chuck | Metalworking | |||
| ENCO no-name chuck or Bison? | Metalworking | |||
| Cuemaking-Metal Lathe Chuck Question? | Metalworking | |||
Linear Mode
