The Turning Dilema - RPMs vs Risk (semi-long)
The Turning Dilema - RPMs vs Risk (semi-long)
I come to turning from The World of Norm (other heroes - Krenov, Maloof and Nakashima). I can adequately use handtools - chisels, dovetail saws, hand planes, cabinet scrapers, some carving gouges, and can set up and safely use a joiner, planer, table saw, shaper, SCMS, router - in or out of a table, drill press, drum sander, OSS. Mortising machine etc. . I’ve got feather boards, hold downs, blade guards and push sticks - and use them. I can put a good edge on just about anything flat backed with a flat bevel - using a Tormek, diamond plates or japanese water stones - with or without a jig. And I can read grain adequately - on flat stock. In The World of Norm, I can mechanically limit the degrees of freedom of movement of both the tool and the stock. With turning, at least the center/ spindle turning I’ve been playing with (for me, if it’s fun it’s playing), it’s the very dynamic brain/ eye / hand coordination that concerns me. Initiating a “cut” properly and completing it properly is requiring far more concentration, coordination and, frankly, stress than it probably should. And RPMs seems to be one of the major causes of my low to moderate anxiety. In The World of Norm, the RPMs of the thing biting off pieces of wood is typically fixed - the more teeth chewing, the smaller each bite is. The slower you feed the stock to the teeth the smaller each bite is. It’s Biting Off More Than You Can Chew which raises all the hell - and launches things - at what seems to be at least Mach 3. In The World of Turning, you’ve got but a single “tooth” - the chisel, gouge or scraper, tool angle, feed rate and RPMs determine the “bite” size. AND, in The World of Turning, unlike in The World of Norm, the “tooth” can follow the grain of the wood - and if it does all hell can break loose. And that leads to my dilema. At 500 RPMS, things happen 1/3rd slower than at 1200 RPMs - eight “bites” per second vs 20 “bites” per second. I “know” that my reaction time is greater than a half a second so when a catch happens, it really doesn’t make much difference whether it happens in 1/10th of a second or 5/100ths of a second - it’s happened before I can possibly react. Now the Mr. Spock part of my brain says “More bites per second, the smaller each bite, and, logically, that’s safer.”. But my white knuckles, clenched teeth - and sometimes “cheeks”, are telling me - “SCREW LOGIC - SLOW IT DOWN!”. So my questions a 1. Recomended roughing to round with a 1/2” or 3/4” roughing gouge RPMS, given the following: - starting with up to 1 1/2” square stock - 10 to 14 inches between centers and stock “approximately” centered 2. Recomended RPMS for spindle turning a 1 inch cylinder 10 - 14 inches long. 3. When you’re turning parts down to pretty small diameters, do you want to work at higher RPMS or lower? 4. Is “best RPMs” a function of the type of wood? I know that pine crushes rather than cuts when using bench chisels while maple, cherry, walnut and, my favorite, mahogany cut nice and clean. So much to learn, so many mistakes to try and avoid. (Turned some year old prunings from a plumb tree. Nice stuff - and FREE! Fun, this turning thing) charlie b aka The Rotationiste in training |
"charlie b" wrote in message ... The Turning Dilema - RPMs vs Risk (semi-long) But my white knuckles, clenched teeth - and sometimes "cheeks", are telling me - "SCREW LOGIC - SLOW IT DOWN!". They're right. It's not so much the number of bites as it is Newton. Remember MV(squared)? I try to keep at pucker factor six, maximum. So my questions a 1. Recomended roughing to round with a 1/2" or 3/4" roughing gouge RPMS, given the following: - starting with up to 1 1/2" square stock - 10 to 14 inches between centers and stock "approximately" centered 500 is good, no more than a thousand. 2. Recomended RPMS for spindle turning a 1 inch cylinder 10 - 14 inches long. Same-o 3. When you're turning parts down to pretty small diameters, do you want to work at higher RPMS or lower? You want to keep a light touch with a sharp tool. Speed? Same-o 4. Is "best RPMs" a function of the type of wood? I know that pine crushes rather than cuts when using bench chisels while maple, cherry, walnut and, my favorite, mahogany cut nice and clean. Best rpms are the ones you feel comfortable with. Favor lower, because the odd chunk that may unexpectedly depart will leave with less available energy to bust your chops. So much to learn, so many mistakes to try and avoid. How about some "rules?" First rule is to avoid anything thrown by the lathe. Don't stand in harm's way at startup, listen and watch for signs that anything's working loose. Keep your on/off switch near the tail of the lathe where you won't have to reach through the zone, either. Second rule is never give away leverage. Keep the toolrest close. It gives you greater mechanical advantage, serves as an iron barrier between you and the work. Third rule is to be methodical - always A-B-C. Anchor the tool to the rest. Turning is about rotating things against a fixed tool to make them round, after all. Bevel to the wood. Lay it right down , then English your way into the cut, letting the bevel guide on the space it's made for itself after it begins. Cut for the curl. Your shavings should be curls, preferably continuous twisted curls, and they should fall, not fly. Before you reach to turn off the lathe, disengage the tool from the cut, lift the bevel, then remove it from the rest. Willing to bet 75% of catches and curses happen because of inattention, not during the cutting, but the (inadequate) clearing. |
In article , "George" George@least
wrote: How about some "rules?" First rule is to avoid anything thrown by the lathe. Don't stand in harm's way at startup, listen and watch for signs that anything's working loose. Keep your on/off switch near the tail of the lathe where you won't have to reach through the zone, either. And wear a full face shield rated for impact protection...with a hard hat if you like. Things don't always jump the way you think they will. A faceful of wood that's traveling away from the lathe is a bad, painful, and often expensive thing. A faceshield can be had for $10 and up. Cheaper to buy it before the first time, rather than before the second time. Cranking up the speed is a crutch, and mostly a modern-era crutch. Doubly so if you're not doing production turning where 5 minutes more time will impact your income in a bad way. Some expert has claimed (IIRC) that you need never turn above 1000 RPM (or was it 300?). I'd certainly rather have a lathe that went from 100 to 1000 than 500 to 5000. You must control the tool - despite the motor, turning is still essentially a hand-tool activity, and requires user control of the tool (unless you're using a spindle-copying jig, and thats not really turning, IMHO.) Practice on firewood for a while - cheap, guilt-free if it gets damaged beyond reclaiming, and gives you experience. -- Cats, coffee, chocolate...vices to live by |
I like it slow.
I'm turning bowls and plates, and I start at 450, and final cut at 950 rpm. That's it. I do get a smoother cut at the higher speed, so I shift to it after the piece is round and all the corners are gone. I've done less spindle turning, but it has been very satisfactory at the low end of the range. I figure the less speed, the less momentum, the smaller the bruise when it hits me. I do speed things up to 1500 rpm when I polish the wax. I had a 12" laminated plate (old butcher block counter) delaminate on me at that speed. The knot on my arm is still there after two weeks. It's not the bite you are taking that causes the problem, it's the bit that the chisel takes when it develops a mind of its own. I don't like to do white knuckle turning. If I'm putting finger prints into the tool handle, I stop and do a dry run to see where the tool edge is. If I get tense, I catch. It's a wonderful sport. Walt C "charlie b" wrote in message ... The Turning Dilema - RPMs vs Risk (semi-long) I come to turning from The World of Norm (other heroes - Krenov, Maloof and Nakashima). I can adequately use handtools - chisels, dovetail saws, hand planes, cabinet scrapers, some carving gouges, and can set up and safely use a joiner, planer, table saw, shaper, SCMS, router - in or out of a table, drill press, drum sander, OSS. Mortising machine etc. . I've got feather boards, hold downs, blade guards and push sticks - and use them. I can put a good edge on just about anything flat backed with a flat bevel - using a Tormek, diamond plates or japanese water stones - with or without a jig. And I can read grain adequately - on flat stock. In The World of Norm, I can mechanically limit the degrees of freedom of movement of both the tool and the stock. With turning, at least the center/ spindle turning I've been playing with (for me, if it's fun it's playing), it's the very dynamic brain/ eye / hand coordination that concerns me. Initiating a "cut" properly and completing it properly is requiring far more concentration, coordination and, frankly, stress than it probably should. And RPMs seems to be one of the major causes of my low to moderate anxiety. In The World of Norm, the RPMs of the thing biting off pieces of wood is typically fixed - the more teeth chewing, the smaller each bite is. The slower you feed the stock to the teeth the smaller each bite is. It's Biting Off More Than You Can Chew which raises all the hell - and launches things - at what seems to be at least Mach 3. In The World of Turning, you've got but a single "tooth" - the chisel, gouge or scraper, tool angle, feed rate and RPMs determine the "bite" size. AND, in The World of Turning, unlike in The World of Norm, the "tooth" can follow the grain of the wood - and if it does all hell can break loose. And that leads to my dilema. At 500 RPMS, things happen 1/3rd slower than at 1200 RPMs - eight "bites" per second vs 20 "bites" per second. I "know" that my reaction time is greater than a half a second so when a catch happens, it really doesn't make much difference whether it happens in 1/10th of a second or 5/100ths of a second - it's happened before I can possibly react. Now the Mr. Spock part of my brain says "More bites per second, the smaller each bite, and, logically, that's safer.". But my white knuckles, clenched teeth - and sometimes "cheeks", are telling me - "SCREW LOGIC - SLOW IT DOWN!". So my questions a 1. Recomended roughing to round with a 1/2" or 3/4" roughing gouge RPMS, given the following: - starting with up to 1 1/2" square stock - 10 to 14 inches between centers and stock "approximately" centered 2. Recomended RPMS for spindle turning a 1 inch cylinder 10 - 14 inches long. 3. When you're turning parts down to pretty small diameters, do you want to work at higher RPMS or lower? 4. Is "best RPMs" a function of the type of wood? I know that pine crushes rather than cuts when using bench chisels while maple, cherry, walnut and, my favorite, mahogany cut nice and clean. So much to learn, so many mistakes to try and avoid. (Turned some year old prunings from a plumb tree. Nice stuff - and FREE! Fun, this turning thing) charlie b aka The Rotationiste in training |
Charlie b wrote: ...snip.... at least the center/ spindle turning ...snip..
Initiating a "cut" properly and completing it properly is requiring far more concentration, coordination and, frankly, stress than it probably should. And RPMs seems to be one of the major causes of my low to moderate anxiety." Hi Charlie, First, relax. Second, forget RPMs as a number rather hear and feel speed of the turning wood according to the wood, you and the tool. I think RPMs should only be for car mechanics. **Charlie: "In The World of Turning, you've got but a single "tooth" - the chisel, gouge or scraper, tool angle, feed rate and RPMs determine the "bite" size." No, you have your hand or touch and the cutting edge of the tool; this remains the same if your RPMs are 10 or 3,000. **Charlie b: asks rules for: 1. Recomended roughing to round with a 1/2" or 3/4" roughing gouge RPMS, given the following: - starting with up to 1 1/2" square stock - 10 to 14 inches between centers and stock "approximately" centered A 3/4" roughing gouge is a little big for a 1 1/2" square stock that is 10 - 14" long. IF you must have RPMs, I'd use minimum 1,000 with a LIGHT touch. The lower the speed on spindle turning (especially 12" + length) is going to cause catches and not be a pleasant experience. If you use a LIGHT wispy cut until the blank is just about rounded, you won't have chatter or catches. And unless you're turning thin stemmed flowers, chances are you are turning spindles and using dry wood so forget the curls because it's all going to be chips. ** Charlie: "2. Recomended RPMS for spindle turning a 1 inch cylinder 10 - 14 inches long. 3. When you're turning parts down to pretty small diameters, do you want to work at higher RPMS or lower? 4. Is "best RPMs" a function of the type of wood?" Take some maple, cherry, walnut or, your favorite, mahogany and practice. Don't practice on pine or punky wood because you'll get frustrated. Try roughing that 1 1/2" blank with a bowl gouge, any size, see how that feels. Do not worry about flying projectiles because most spindles will crack and both sections will fall before they fly.........bowls fly! Charlie, I've been supporting myself with architectural reproduction work (aka spindle turning) for over 10 years. I've gotten catches and broken a lot of very thin spindles. I don't try to beat the clock so I guess I couldn't be labeled as a production turner. Some times you have to lower the speed for a nice clean cut, some times you have to raise the speed for a nice clean cut and some times you just aren't going to get a nice clean cut (throw that piece of wood away and get a better one). I rough with a roughing gouge, a skew, a bowl gouge and/or a detail gouge. Again, relax and forget the risk vs rpms because the only risk is (as George said) "inattentiveness". There really are no hard fast rules except BE CAREFUL; use whatever tool feels and works good for you, use whatever speed you like or get the best results. Try them all then decide for yourself what works for you. Now go have fun. Ruth www.torne-lignum.com |
charlie b wrote:
snip (Turned some year old prunings from a plumb tree. Going to make some plumb bobs, eh? -- Gerald Ross Cochran, GA But I forgot all about the Amnesia Conference!! ----== 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 =---- |
"Ecnerwal" wrote: (clip) Cheaper to buy it before the first time, rather than before the second time.(clip) ^^^^^^^^^^^^^^^^ Good way of putting it. I like economy of words, so I won't say more. |
Good way of putting it. I like economy of words, so I won't say more.
I second that on ALL the great info and guidance. I especially like the advice on using the tools you are comfortable with at speeds you like. I recently gave a demo on turning 1" to 2" mushrooms on multiaxis so I could make the stem lean over and look a little dimensioned, not round. After I turn the cap, I use only my diamond point parting tool for hollowing the cap, turning the multi-axis stem, and them the base. I have a finished mushroom in 10 minutes that requires very little sanding. No one could get past me using the parting chisel so extensively. Making a mushroom I use the tool as a skew, a scraper, and a detail gouge. Not a single person in my club will even try it... I took a class years ago from a guy that told me that he just ground his tools the way they seem to work best for him, and never worried about the "right tool" or the "right grind". I have been on that track ever since. You should see what I have done to my poor 3/8" bowl gouge... But I am at the point where I can turn my lamp pulls, mushrooms, candle bases etc. all day long and actually use about 4 tools all day long. The only thing I would add that is hidden in some of these postings is to practice, practice, practice. Learn the most popular grinds, then modify to suit yourself. The best thing I would say on top of all the good stuff you have gotten is to join a woodturning club. Most of the guys there in any of the clubs I have visited are great about showing technique. A modification in stance, a small angle change in how you hold a tool, and sometimes just finding out what the tools do is a tremedous leg up. Good luck! Post your questions here... there are some great folks that are pretty generous with their time to teach. Say like... Ruth for example. Robert |
When I started seriously thinking about getting into woodworking
I found rec.woodworking. Got a lot of good advice, direction and help from a lot of knowledgable, talented people. Now, when I can I try to follow their example and lend a helping hand when I can. This group is a lot calmer AND just as helpful. I think I'm gonna like hanging out here as well. Thanks - much appreciated. Hope I can be an beneficial addition to the group. charlie b (I took the midi lathe off my bench and semi-put it away for a while. Had to do that so I wouldn't try turning toothpicks. This turning thing is really addictive - and a lot less expensive than what it costs to build solid wood furniture and the like. Have a To Do List I have to get back to - utility shelves, a big gate with arched top and panels, a table to glue up, a cabinet for younger son's LPs (he's a retro throw back) a door and drawer faces to put on to finish my sharpening station cabinet AND the coopered door mini-cabinet for router bits. Play time's over for now - back to "work") |
In article ,
charlie b wrote: 3. When you’re turning parts down to pretty small diameters, do you want to work at higher RPMS or lower? 4. Is “best RPMs” a function of the type of wood? I know that pine crushes rather than cuts when using bench chisels while maple, cherry, walnut and, my favorite, mahogany cut nice and clean. Hello Rotationista, I'll echo what Ruth said about relaxing. Catches happen - it's a part of the risk of creating work in which the person is in complete, unrestricted control of the cutting edge. People are fallible when presenting a sharp edge to spinning wood. But if you're tense and stiff the outcome could be injurious or at the least unsettling to your confidence. A moderately light touch is all that's required. Think about feeding a board across a jointer or into a table saw. Being tense and pushing against the machine's ability to cut is bound to lead to an "event" or an injury. When you push against the cut you'll be off balance if something at the point of the cut changes - leading to a potentially nasty situation. A similar understanding is in order for woodturning. Allow the legs, shoulders, arms and fingers to control the rate of cut as well as the direction. (As Ellsworth recommends in one of his videos, let the large muscles do the majority of the work and let the small muscles put in the delicate work.) Take light cuts. No, lighter than that. Allow the edge of the tool to do the work. If you do happen to present the edge incorrectly and get a catch your balance won't be affected and the tool isn't in a death grip which will worsen the catch. A moderately light touch allows you to pull back more quickly and there's no body weight in the cut that you've got to reverse direction and pull back. My personal preference for lathe speed is either 1250 or 1800 rpm - and 85% of the time it's 1800. I turn a fair number of spindles and start out there. The only time I turn more slowly is when I have an unbalanced piece and the only times I turn faster is when polishing. I generally turn my bowls at 1800 and the alabaster rock I've been trying out lately goes at 1250. After 4 years of turning a lot of wood, I still get catches. But they haven't been disastrous for about 3.5 years now - they're usually just a spiral gouge that screws up a bead on my last finessing pass. Ain't that always the way? -- Owen Lowe Northwest Woodturners, Cascade Woodturners, Pacific Northwest Woodturning Guild ___ Safety Tip'o'th'week: Never grind aluminum and steel or iron on the same machine or workstation - Thermite. http://www.hanford.gov/lessons/sitell/ll01/2001-36.htm |
Owen wrote: ....snip.....
After 4 years of turning a lot of wood, I still get catches. But they haven't been disastrous for about 3.5 years now - they're usually just a spiral gouge that screws up a bead on my last finessing pass. Ain't that always the way? Why is that, Owen?!? And that "last finessing pass" could easily be done with the 120 grit tool. : ) Have you ever had a really cool spiral gouge and wish you could intentionally reproduce it? Ruth www.torne-lignum.com "CLTL" |
Gerald Ross wrote:
charlie b wrote: =20 snip =20 =20 (Turned some year old prunings from a plumb tree. =20 =20 Going to make some plumb bobs, eh? =20 I think he was giving it to us straight up - no juicy stuff here --=20 course it will pass. --=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 |
On Wed, 17 Aug 2005 18:19:02 -0400, "George" George@least wrote:
snip Before you reach to turn off the lathe, disengage the tool from the cut, lift the bevel, then remove it from the rest. Willing to bet 75% of catches and curses happen because of inattention, not during the cutting, but the (inadequate) clearing. So damn true.... It's just SO easy to catch the edge of a goblet or the side of a bowl when you think the cut is "over" but haven't got the chisel out of reach of the wood... I hate when that happens.. one of those things that make you feel really dumb when you do it, because you "know better".. mac Please remove splinters before emailing |
One question that always comes up at demos that I (or anyone else does)
is "At what speed are you turning?" On my lathe, the speed knob fell off, and just won't stay on any more, plus the readout is on the back side of the lathe (PM3520). I always say to turn at what ever speed you feel comfortable with. Rough bowl blanks, turn the lathe up until it starts to wobble and vibrate, then back it off until it is smooth. I turn all bowls on the lower speed range, so small ones will finish turn at 1750. When I started, I didn't turn over 500. With spindles, it is the same way. I turn out a number of basting brushes. When starting, I would turn in the 500 range also. Now 3000 seems slow. Adjust speeds to your comfort level. Start slow and work your way up. robo hippy |
On Wed, 17 Aug 2005 23:19:39 GMT, Ecnerwal
wrote: Cranking up the speed is a crutch, and mostly a modern-era crutch. Doubly so if you're not doing production turning where 5 minutes more time will impact your income in a bad way. Some expert has claimed (IIRC) that you need never turn above 1000 RPM (or was it 300?). I'd certainly rather have a lathe that went from 100 to 1000 than 500 to 5000. I think speed is a relative thing.. I've turned small goblets (3/4" - 1 1/2" diameter) at 850 or 1,100... but when I'm roughing a 12 inch bowl, I wish the Min. speed of my lathe was a lot less than 450.... I've considered changing the pulleys, since it (jet 1442) has 8 speeds and I've never used anything over the 4th speed... I can't imagine turning ANYTHING at 3,000 rpm.. mac Please remove splinters before emailing |
On Wed, 17 Aug 2005 22:50:11 -0700, charlie b wrote:
When I started seriously thinking about getting into woodworking I found rec.woodworking. Got a lot of good advice, direction and help from a lot of knowledgable, talented people. Now, when I can I try to follow their example and lend a helping hand when I can. This group is a lot calmer AND just as helpful. I think I'm gonna like hanging out here as well. Thanks - much appreciated. Hope I can be an beneficial addition to the group. charlie b (I took the midi lathe off my bench and semi-put it away for a while. Had to do that so I wouldn't try turning toothpicks. This turning thing is really addictive - and a lot less expensive than what it costs to build solid wood furniture and the like. Have a To Do List I have to get back to - utility shelves, a big gate with arched top and panels, a table to glue up, a cabinet for younger son's LPs (he's a retro throw back) a door and drawer faces to put on to finish my sharpening station cabinet AND the coopered door mini-cabinet for router bits. Play time's over for now - back to "work") Charlie... while you're doing your flat work, add another item to your list... design a stand for your midi and get it off the bench.. With your design and woodworking talents, you could make a very functional stand that would probably include tool holders, shaving catcher, wheels, etc., etc... mac Please remove splinters before emailing |
On Wed, 17 Aug 2005 23:25:58 -0700, Owen Lowe wrote:
hmm... Owen has got me thinking, which is a GOOD thing.. *g* I used to be constantly worried about things launched off the lathe... and thinking back on the 15 or 20 times (at least) that this has happened, none has done much more than drop and roll... OTOH, most of the tools that I use for flat work have me worried about kick back, which IMO is worse than a bowl falling off the lathe.. Hello Rotationista, I'll echo what Ruth said about relaxing. Catches happen - it's a part of the risk of creating work in which the person is in complete, unrestricted control of the cutting edge. People are fallible when presenting a sharp edge to spinning wood. But if you're tense and stiff the outcome could be injurious or at the least unsettling to your confidence. A moderately light touch is all that's required. Think about feeding a board across a jointer or into a table saw. Being tense and pushing against the machine's ability to cut is bound to lead to an "event" or an injury. When you push against the cut you'll be off balance if something at the point of the cut changes - leading to a potentially nasty situation. A similar understanding is in order for woodturning. Allow the legs, shoulders, arms and fingers to control the rate of cut as well as the direction. (As Ellsworth recommends in one of his videos, let the large muscles do the majority of the work and let the small muscles put in the delicate work.) Take light cuts. No, lighter than that. Allow the edge of the tool to do the work. If you do happen to present the edge incorrectly and get a catch your balance won't be affected and the tool isn't in a death grip which will worsen the catch. A moderately light touch allows you to pull back more quickly and there's no body weight in the cut that you've got to reverse direction and pull back. My personal preference for lathe speed is either 1250 or 1800 rpm - and 85% of the time it's 1800. I turn a fair number of spindles and start out there. The only time I turn more slowly is when I have an unbalanced piece and the only times I turn faster is when polishing. I generally turn my bowls at 1800 and the alabaster rock I've been trying out lately goes at 1250. After 4 years of turning a lot of wood, I still get catches. But they haven't been disastrous for about 3.5 years now - they're usually just a spiral gouge that screws up a bead on my last finessing pass. Ain't that always the way? mac Please remove splinters before emailing |
"charlie b" wrote in message ... Now the Mr. Spock part of my brain says "More bites per second, the smaller each bite, and, logically, that's safer.". But my white knuckles, clenched teeth - and sometimes "cheeks", are telling me - "SCREW LOGIC - SLOW IT DOWN!". In my opinion, you are going at the problem from the wrong side. Of course the higher speeds should be used only when you feel safe (and I mean _safe_) to use them. Your problem is not the speed (was it Ralph Nader who coined the phrase "Unsafe at any speed"?) but the danger of getting a catch. The cure is not in choosing a slower speed, which only leads to "slower" catches, but learning to present the different tools to the piece in a safe, non-catching manner. There _are_ ways and means, you know, as soon as you find yourself a qualified instructor. In sports, they say that He who coaches himself has a fool for a trainee. This is doubly true in woodturning, since the tools of the trade are much sharper than most sportinggear. Bjarte |
In article .com,
"robo hippy" wrote: I always say to turn at what ever speed you feel comfortable with. Rough bowl blanks, turn the lathe up until it starts to wobble and vibrate, then back it off until it is smooth. I turn all bowls on the lower speed range, so small ones will finish turn at 1750. When I started, I didn't turn over 500. With spindles, it is the same way. I turn out a number of basting brushes. When starting, I would turn in the 500 range also. Now 3000 seems slow. Adjust speeds to your comfort level. Start slow and work your way up. Have you ever seen Jimmy Clewes demonstrate? He cranks the speed up to max and leaves it there. Quite a few in the front row of the group made nervous chuckles and shrank in their seats a tad but I'm sure Clewes wouldn't do it if he had any doubts. He commented something on the lines that higher speeds make a smoother and more controlled cutting action - if I remember right. -- Owen Lowe Northwest Woodturners, Cascade Woodturners, Pacific Northwest Woodturning Guild ___ Safety Tip'o'th'week: Never grind aluminum and steel or iron on the same machine or workstation - Thermite. http://www.hanford.gov/lessons/sitell/ll01/2001-36.htm |
"Owen Lowe" wrote in message ... He commented something on the lines that higher speeds make a smoother and more controlled cutting action - if I remember right. Wonder how he explains the cut you get with a carving tool at considerably below 5 fpm? |
George wrote:
Best rpms are the ones you feel comfortable with. Favor lower, because the odd chunk that may unexpectedly depart will leave with less available energy to bust your chops. I think it was John Jordan that said "If you think a piece is turning fast, then it is too fast!" Because of reaction time, faster can be better - less time for you to drive your tool into a position to cause a catastrophic catch. But keep your turning to a comfortable speed - that speed will go up over time as you gain more confidence. How about some "rules?" First rule is to avoid anything thrown by the lathe. Don't stand in harm's way at startup, listen and watch for signs that anything's working loose. Keep your on/off switch near the tail of the lathe where you won't have to reach through the zone, either. Second rule is never give away leverage. Keep the toolrest close. It gives you greater mechanical advantage, serves as an iron barrier between you and the work. Third rule is to be methodical - always A-B-C. Anchor the tool to the rest. Turning is about rotating things against a fixed tool to make them round, after all. Bevel to the wood. Lay it right down , then English your way into the cut, letting the bevel guide on the space it's made for itself after it begins. Cut for the curl. Your shavings should be curls, preferably continuous twisted curls, and they should fall, not fly. Before you reach to turn off the lathe, disengage the tool from the cut, lift the bevel, then remove it from the rest. Willing to bet 75% of catches and curses happen because of inattention, not during the cutting, but the (inadequate) clearing. Corollary to the last, before you turn on the lathe, get the tool away from the work, then approach the tool rest FIRST, then the turning wood. |
Owen Lowe wrote:
He commented something on the lines that higher speeds make a smoother and more controlled cutting action - if I remember right. For roughing down a spindle (turning it from a square section to a cylinder) the higher speed makes it easier for the weight of your body to overcome the percussive effect the corners of the wood have as they slam into the cutting edge. The limiting factor of course is the speed the lathe will turn the workpiece without vibration. A sharp tool, properly presented, will reduce the force on the tool. Confidence too is important. You need to be confident the work piece is securely mounted and isn't going to come flying off. Beginners can sometimes benefit from adjusting the drive belt so it will slip if they have a catch; or use a Stebcenter to drive the workpiece. Start with light cuts; when you approach the wood with the roughing gouge let the heel of the bevel touch the wood first, then carfully raise the handle until the cutting edge starts cutting, then make your cut along the length of wood. CharlieB made a very astute observation: "In The World of Norm, I can mechanically limit the degrees of freedom of movement of both the tool and the stock. With turning, at least the center/ spindle turning I’ve been playing with (for me, if it’s fun it’s playing), it’s the very dynamic brain/ eye / hand coordination that concerns me. Initiating a “cut” properly and completing it properly is requiring far more concentration, coordination and, frankly, stress than it probably should." Yes, woodturning with unrestrained hand-held tools is very much a manual skill. It starts with where you place your feet and ends with how you manipulate and control the tool, getting feedback from touch, eyes and ears. Just like an athlete has to train their body parts to work together, so does a woodturner. -- Derek Andrews, woodturner http://www.seafoamwoodturning.com http://chipshop.blogspot.com http://groups.yahoo.com/group/toolrest/ |
Pounding the pulpit in ,
charlie b did expound thusly: In The World of Turning, you've got but a single "tooth" - the chisel, gouge or scraper, tool angle, feed rate and RPMs determine the "bite" size. AND, in The World of Turning, unlike in The World of Norm, the "tooth" can follow the grain of the wood - and if it does all hell can break loose. And that leads to my dilema. At 500 RPMS, things happen 1/3rd slower than at 1200 RPMs - eight "bites" per second vs 20 "bites" per second. I "know" that my reaction time is greater than a half a second so when a catch happens, it really doesn't make much difference whether it happens in 1/10th of a second or 5/100ths of a second - it's happened before I can possibly react. Here's where your Mr. Spock part must be otherwise occupied. Do Vulcan's take smoko's? In the World Of Norm, if you take too big a bite you risk biting the hand that... so naturally you slow down the feed rate. In the World of Turning it's exactly the same, except you've only got one tooth and it's not moving. It's not making *any* bites per second; you could say it's making one continuous bite. At low RPM your feeding less feet per minute to that single tooth than you would at high at high RPM. If it's biting the hand, slow down the feed rate by dropping the RPM! Now the Mr. Spock part of my brain says "More bites per second, the smaller each bite, and, logically, that's safer.". But my white knuckles, clenched teeth - and sometimes "cheeks", are telling me - "SCREW LOGIC - SLOW IT DOWN!". No, what's really happening is the Mr Spock part has shown he really does have a human side and logic based on faulty premises is dangerous to your enterprise while Scottie, down in the bowels of the ship, is screaming "She cannae take much more ae this! Get a new Science Officer!" -- - Andy ---------------------------------------------------------------------- No tools are lost by lending, except those you wanted to keep. |
Do you mean PLUM ? ? ?
"WillR" wrote in message . .. Gerald Ross wrote: charlie b wrote: snip (Turned some year old prunings from a plumb tree. Going to make some plumb bobs, eh? I think he was giving it to us straight up - no juicy stuff here -- course it will pass. -- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it.” George Bernard Shaw |
In article ,
"Ruth Niles" wrote: After 4 years of turning a lot of wood, I still get catches. But they haven't been disastrous for about 3.5 years now - they're usually just a spiral gouge that screws up a bead on my last finessing pass. Ain't that always the way? Why is that, Owen?!? And that "last finessing pass" could easily be done with the 120 grit tool. : ) Have you ever had a really cool spiral gouge and wish you could intentionally reproduce it? 120 tool - haven't got one. My coarsest tool is 220. ;) I have tried to get the spiral intentionally, but with a 500 RPM lowest speed it's a toughie. -- Owen Lowe Northwest Woodturners, Cascade Woodturners, Pacific Northwest Woodturning Guild ___ Safety Tip'o'th'week: Never grind aluminum and steel or iron on the same machine or workstation - Thermite. http://www.hanford.gov/lessons/sitell/ll01/2001-36.htm |
On Sat, 20 Aug 2005 19:32:57 -0500, "Barry N. Turner"
wrote: maybe it was a very straight tree? Do you mean PLUM ? ? ? "WillR" wrote in message ... Gerald Ross wrote: charlie b wrote: snip (Turned some year old prunings from a plumb tree. Going to make some plumb bobs, eh? I think he was giving it to us straight up - no juicy stuff here -- course it will pass. mac Please remove splinters before emailing |
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