Boring a super smooth surface
Hi all,
Is there a way I can get a mirror like finish on a turned piece of metal? I know I can use 1000 grit and finer on a piece as it is chucked and turning in a lather, but how about the bored hole? How would I get a, say, 1/4" or 3/8" internal surface glass smooth? I am thinking of some sort of expanding reamer that I could put a 1000 grit wet/dry sheet around and insert it in the hole as it is turning...seems like I would just bunch up the paper though ;-) Anyone ever have to get something "barring" smooth internally....what did ya use? Thanks again gang....as always, any help is greatly appreciated John |
I think that the tool your looking for is a lap or hone. You can also ball
size a hole and get a good surface. Some depends on the material your polishing. For just polishing without worrying about real accurate size you can charge a bit of cloth with polishing compound and put it in a folded wire and run it with a drill motor. Describe to us what the material, size restrictions on finished size, and what the hole is to be used for. then some more accurate answers can be given. lg no neat sig line "CAMCOMPCO" wrote in message oups.com... Hi all, Is there a way I can get a mirror like finish on a turned piece of metal? Anyone ever have to get something "barring" smooth internally....what did ya use? Do you mean "bearing smooth"? Thanks again gang....as always, any help is greatly appreciated John |
"CAMCOMPCO" wrote in
oups.com: Hi all, Is there a way I can get a mirror like finish on a turned piece of metal? I know I can use 1000 grit and finer on a piece as it is chucked and turning in a lather, but how about the bored hole? How would I get a, say, 1/4" or 3/8" internal surface glass smooth? I am thinking of some sort of expanding reamer that I could put a 1000 grit wet/dry sheet around and insert it in the hole as it is turning...seems like I would just bunch up the paper though ;-) Anyone ever have to get something "barring" smooth internally....what did ya use? Thanks again gang....as always, any help is greatly appreciated A burnishing tool is the usual way. Barring that, if it's a through hole you can "ballize" the hole. In other words, drill and ream the hole slightly undersize then press the appropriate size ball bearing ball through the hole. You can also use emory wrapped on a wooden dowel to polish the I.D. (put a slot on the end to help with the wrap) and then follow up with a split lap and some lapping compund. -- Dan |
Yes, bearing, 7 years of University studies never taught me to second
guess spell check ;-) This is as a general skill question...I want the hole to be exactly XYZ when I am done, in practice, +/- 0.001. Now, I can get the hole that precise, just cant get it glass smooth. If I am to understand the ballize description provided by Dan, the hardened ball bearing is pushed through the hole, essentially smashing the bumps and scratched flat. Now I have a reason to hunt for ball bearings on ebay. I'll try the emery wrap, just don't want to sand away accuracy....I give it a try tomorrow provide update... Cheers, and thanks again Larry and Dan John |
Yes, bearing, 7 years of University studies never taught me to second
guess spell check ;-) This is as a general skill question...I want the hole to be exactly XYZ when I am done, in practice, +/- 0.001. Now, I can get the hole that precise, just cant get it glass smooth. If I am to understand the ballize description provided by Dan, the hardened ball bearing is pushed through the hole, essentially smashing the bumps and scratched flat. Now I have a reason to hunt for ball bearings on ebay. I'll try the emery wrap, just don't want to sand away accuracy....I give it a try tomorrow provide update... Cheers, and thanks again Larry and Dan John |
"CAMCOMPCO" wrote in
oups.com: If I am to understand the ballize description provided by Dan, the hardened ball bearing is pushed through the hole, essentially smashing the bumps and scratched flat. Now I have a reason to hunt for ball bearings on ebay. Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 -- Dan |
"D Murphy" wrote in message
... "CAMCOMPCO" wrote in oups.com: If I am to understand the ballize description provided by Dan, the hardened ball bearing is pushed through the hole, essentially smashing the bumps and scratched flat. Now I have a reason to hunt for ball bearings on ebay. Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( - Michael |
Just what I was looking for...thanks a bunch
John |
Last weekend I made an eccentric strap, similar to a connecting rod, for a
small steam engine. The eccentric strap (follower) needed to fit the eccentric loosely enough to turn with usu. oil film. First, the strap was made to outside dimensions with the bolt holes drilled and tapped - flats were left on 2 sides perpendicular to the split lines, which is the normal profile for an eccentric strap. Then the rough opening was bored to within a few thousandths of finished size which was to be 0.806". Next, I made a pair of go-no-go gauges on the lathe, of 0.806" and 0.808". (Wish I had a set of gauge rods or balls) The strap was repositioned in the mill with the flats oriented for splitting. It was split with a 0.020" slitting saw through each side and the sides tightly bolted together. Next, it was recentered in the mill and bored to near 0.806". Several boring passes were made until the 0.806" gauge would just barely "go". The 0.808" gauge would not "go". That yielded a very round hole (after splitting) of very nearly 0.806", maybe 1/2 to 1 thousandth over, but certainly between 0.806" and 0.808". Measuring with test gauges is a lot less "nervous" than the usu. small hole gauges, at least for me. One thing to note: When very nearly to finished size, 1 or 2 tenths can be removed by running the boring tool down into the hole again, maybe more than once. Bob Swinney "CAMCOMPCO" wrote in message oups.com... Hi all, Is there a way I can get a mirror like finish on a turned piece of metal? I know I can use 1000 grit and finer on a piece as it is chucked and turning in a lather, but how about the bored hole? How would I get a, say, 1/4" or 3/8" internal surface glass smooth? I am thinking of some sort of expanding reamer that I could put a 1000 grit wet/dry sheet around and insert it in the hole as it is turning...seems like I would just bunch up the paper though ;-) Anyone ever have to get something "barring" smooth internally....what did ya use? Thanks again gang....as always, any help is greatly appreciated John |
The first thing is to bore the hole properly. You can get smooth surfaces
on the outside of a turning, you can do the same for the inside of a bore with the right geometry on the cutting tip. After that, the ball or a rod with a large end will definietely roll over the sharp edges but will also make the scrapes along the radius of the bore rather than around the bore. This may be more harmful than leaving a slightly rougher surface around the bore. Better would be to hone with either honing cutters or stones to keep the right orientation of the grooves that are left and get the right size for the hole. If you're making a split bearing surface, don't forget to use Plastigage on the bearing to make sure that it is the right clearance that you desire. The Plastigage is available at any auto machine shop or better auto parts store. Once you have used the stuff on a bearing and see how well it works, you'll never go back to any othe method of checking bearing clearances. -- Why do penguins walk so far to get to their nesting grounds? |
Right on, Bob! I totally agree; it is unwise to force anything through a
finished hole. Doing so, may bring the hole "to size", but it will surely leave minute damage of its own. Thanks for the tip on Plastigage. I will check on it. Bob Swinney "Bob May" wrote in message ... The first thing is to bore the hole properly. You can get smooth surfaces on the outside of a turning, you can do the same for the inside of a bore with the right geometry on the cutting tip. After that, the ball or a rod with a large end will definietely roll over the sharp edges but will also make the scrapes along the radius of the bore rather than around the bore. This may be more harmful than leaving a slightly rougher surface around the bore. Better would be to hone with either honing cutters or stones to keep the right orientation of the grooves that are left and get the right size for the hole. If you're making a split bearing surface, don't forget to use Plastigage on the bearing to make sure that it is the right clearance that you desire. The Plastigage is available at any auto machine shop or better auto parts store. Once you have used the stuff on a bearing and see how well it works, you'll never go back to any othe method of checking bearing clearances. -- Why do penguins walk so far to get to their nesting grounds? |
So is this a vote for not "ballizing" the hole with a bearing.....Dan,
what say you. Have you had success with it? It's interesting to note how opinions on certain topics can generate both support and condemnation at the same time... Thoughts and comments from others...I guess I am going to cram a ball in the hole, cut the "tube" open and check with a microscope myself....Once I get my ball bearings in, I'll check and get back to you all with the findings. By the way, I never commented on the material....mostly CRS, SS or Aluminum (mostly fortal these days). Thanks again all. John |
On 26 Sep 2005 15:09:01 -0700, "CAMCOMPCO"
wrote: So is this a vote for not "ballizing" the hole with a bearing.....Dan, what say you. Have you had success with it? It's interesting to note how opinions on certain topics can generate both support and condemnation at the same time... Thoughts and comments from others...I guess I am going to cram a ball in the hole, cut the "tube" open and check with a microscope myself....Once I get my ball bearings in, I'll check and get back to you all with the findings. By the way, I never commented on the material....mostly CRS, SS or Aluminum (mostly fortal these days). Thanks again all. John John, You will find that gummier metals, like crs, will give you a better finish than harder materials. Be sure to use the correct lube. Cheers, Eric R Snow, E T Precision Machine |
On Mon, 26 Sep 2005 16:16:06 -0700, Eric R Snow wrote: On 26 Sep 2005 15:09:01 -0700, "CAMCOMPCO" wrote: SNIP John, You will find that gummier metals, like crs, will give you a better finish than harder materials. Be sure to use the correct lube. Cheers, Eric R Snow, E T Precision Machine Hey Eric and John, Owwwwww...gotta diagree with THAT Eric. The harder the metal, the better the surface will get, if done properly. Mirror, and I mean MIRROR finishes in say D-2 are done by "hand men", whose job it is to polish (and keep with-in size) the suface left by mill or lathe. They start off with what-ever is rerquired in nthe 40 to 80 grit range, and finsih with diamond paste, usally with a Foredom or Dumore hand-piece. Take care. Brian Lawson, Bothwell, Ontario. |
I could be wrong Brian, but, I think Eric may have been referring to
the Ballizing part from above, Correct me if I am wrong Eric. Now, given that, Brian, you might still be absolutely correct :-) Cheers |
Ballsizing is a fairly common commercial method of sizing and finishing
holes. Should be lots of references to in on the web. Dan |
On Mon, 26 Sep 2005 20:20:29 -0400, Brian Lawson
wrote: On Mon, 26 Sep 2005 16:16:06 -0700, Eric R Snow wrote: On 26 Sep 2005 15:09:01 -0700, "CAMCOMPCO" wrote: SNIP John, You will find that gummier metals, like crs, will give you a better finish than harder materials. Be sure to use the correct lube. Cheers, Eric R Snow, E T Precision Machine Hey Eric and John, Owwwwww...gotta diagree with THAT Eric. The harder the metal, the better the surface will get, if done properly. Mirror, and I mean MIRROR finishes in say D-2 are done by "hand men", whose job it is to polish (and keep with-in size) the suface left by mill or lathe. They start off with what-ever is rerquired in nthe 40 to 80 grit range, and finsih with diamond paste, usally with a Foredom or Dumore hand-piece. Take care. Brian Lawson, Bothwell, Ontario. Brian, I meant that gummier materials will look better with ballsizing than hard materials. My experience with ballsizing and roller burnishing is limited, but that's the way it always worked for me, and was what I was told would happen. Like form tapping. gummier, to a point, is better, Of course, harder materials will polish up better. Eric |
"DeepDiver" wrote in
: "D Murphy" wrote in message ... "CAMCOMPCO" wrote in oups.com: If I am to understand the ballize description provided by Dan, the hardened ball bearing is pushed through the hole, essentially smashing the bumps and scratched flat. Now I have a reason to hunt for ball bearings on ebay. Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( Don't know, but he must have bought a dump truck full of "inch" sized ones at an auction or something. He's been selling them on ebay for some time now. -- Dan |
"CAMCOMPCO" wrote in
oups.com: So is this a vote for not "ballizing" the hole with a bearing.....Dan, what say you. Have you had success with it? It's interesting to note how opinions on certain topics can generate both support and condemnation at the same time... Thoughts and comments from others...I guess I am going to cram a ball in the hole, cut the "tube" open and check with a microscope myself....Once I get my ball bearings in, I'll check and get back to you all with the findings. By the way, I never commented on the material....mostly CRS, SS or Aluminum (mostly fortal these days). It's a crude form of burnishing. Thousands upon thousands of parts are burnished everyday. This type of thing would be a big no-no in a medical implant where impurities can get "rolled in", or in a critical application where surface integrity was important, say in a tool steel that was to be heat treated later. On materials that work harden it may raise the hardness slightly. In all likelyhood the Aluminum might not work as well as the stainless or CRS. The trick is to get the hole straight, to the right size, and finish to start with. That might take a little experimentation. As far as burnishing a bearing surface, It's done all of the time. It's how .0001" diameter tolerances are held on Swiss screw machine on the tiny shafts inside clocks and watches. It's also how many manufacturers of power tools size the shafts that run in race bearings. The downside to using a ball is that it will happily follow a crooked hole, and a big high spot in the hole will tend to push the ball over to the lower side. -- Dan |
In article , spamto154
@comcast.net says... "DeepDiver" wrote in : Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( Don't know, but he must have bought a dump truck full of "inch" sized ones at an auction or something. He's been selling them on ebay for some time now. Cheaper, and metric sizes as well, from McMaster-Carr. Ned Simmons |
I used to manufacture an aluminum valve that had a polished bore.
I mounted a small permanently-lubricated ball-bearing assembly (sealed both sides) on a stiff rod and clamped that in the lathe turret, and clamped the valve body in the chuck. Spun the body and fed the bearing slowly into the bore using power feed and some pressure, and got a usable surface. I got the best finish when I had ground the bearing's outer race to a barrel shape, and polished that. Minimum bore size will be limited by the bearing OD, of course, and for smaller holes there are proper roller-burnishing tools available. They cost plenty, and only fit given sizes. Dan |
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Ned Simmons wrote in
: In article , spamto154 @comcast.net says... "DeepDiver" wrote in : Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( Don't know, but he must have bought a dump truck full of "inch" sized ones at an auction or something. He's been selling them on ebay for some time now. Cheaper, and metric sizes as well, from McMaster-Carr. True, but not the same grade/material. -- Dan |
jim rozen wrote:
In article .com, says... I used to manufacture an aluminum valve that had a polished bore. I mounted a small permanently-lubricated ball-bearing assembly (sealed both sides) on a stiff rod and clamped that in the lathe turret, and clamped the valve body in the chuck. Spun the body and fed the bearing slowly into the bore using power feed and some pressure, and got a usable surface. I got the best finish when I had ground the bearing's outer race to a barrel shape, and polished that. How much undersized from the bearing OD did you leave the bore to start? Jim On a related subject I was making a cross slide stop for my Southbend lathe http://www.rupert.net/~solar/SOUTHBEND13.html. The materials at hand where a salvaged chunk of cast iron (broken Record vice) and some string trimmer shafting. BTW - string trimmer shafting is high quality, precision machined carbon steel more or less equal to drill rod - NEVER THROW IT OUT and if you come accross some - grab it. I wanted a hole (actually two) drilled in the cast iron that would give a sliding, no shake fit for the shafting. I forget which number drill gave the loose fit but the next smaller size was a somewhat too tight fit - light press? I drilled the smaller size and then used a length of the shafting in this manner. I chucked it in the lathe and applied a vibrating engraver to the rotating shaft. Then I chucked the (now modified with vibrator warts) shaft in my drill press and jammed that through the undersized hole in the cast iron - rerady for disaster that never came. The result was a *perfect fit*. Pushing the shaft through the hole felt like pushing against a well tuned dashpot (and still does after several years of use). A buddy, and my maching guru came by later that day for a rum and coke session. I dragged him down to the shop to show off my latest triumph. As soon as I said "no shake" he got that "total BS" look in his eye and grabbed the protuding shaft. Try as he might he could not detect *any* play! This guy had forgotten more about machining than I will *ever* learn. Essentially, I guess, I sort of 'burnished' that hole. Regards. Ken. |
In article , spamto154
@comcast.net says... Ned Simmons wrote in : In article , spamto154 @comcast.net says... "DeepDiver" wrote in : Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( Don't know, but he must have bought a dump truck full of "inch" sized ones at an auction or something. He's been selling them on ebay for some time now. Cheaper, and metric sizes as well, from McMaster-Carr. True, but not the same grade/material. See McMaster page 3394, exactly the same grade and material - Grade 25, 52100 steel. For example 100 1/4" balls from McM are $3.97 (p/n 9528K15), on ebay $9.99 (Item number: 4578478224). Ned Simmons |
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DoN. Nichols wrote:
According to Allen : wrote: I used to manufacture an aluminum valve that had a polished bore. I mounted a small permanently-lubricated ball-bearing assembly (sealed both sides) on a stiff rod and clamped that in the lathe turret, and clamped the valve body in the chuck. Spun the body and fed the bearing slowly into the bore using power feed and some pressure, and got a usable surface. I got the best finish when I had ground the bearing's outer race to a barrel shape, and polished that. Minimum bore size will be limited by the bearing OD, of course, and for smaller holes there are proper roller-burnishing tools available. They cost plenty, and only fit given sizes. Dan Thanks for the tip I can visualize you forcing the bearings into the hole and the outer race of the bearings picking up the same RPM from the hole as the two meet. So the relative positions of the bearing race and the hole remain constant throughout the push and withdrawal. Now, if my understanding of what you are doing is correct, then is there any particular advantage drawn from having the chuck rotating? The operation appears not unlike swaging a barrel. The impression that I got was that the OD of the bearing was smaller than the ID of the bore, so it rolled around the bore as the workpiece rotated. (The "some pressure" would be pressure of the roller against the side wall of the bore, not axial pressure. Thus, it became a form of roller burnishing tool. Not as stiff as one with three rollers pressing into the bore at 120 degree spacing, but for a soft workpiece material, it should suffice. Enjoy, DoN. That makes sense. Good call. I was thinking more of a swaging operation but I can see I was wrong. A |
Ned Simmons wrote in
: In article , spamto154 @comcast.net says... Ned Simmons wrote in : In article , spamto154 @comcast.net says... "DeepDiver" wrote in : Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( Don't know, but he must have bought a dump truck full of "inch" sized ones at an auction or something. He's been selling them on ebay for some time now. Cheaper, and metric sizes as well, from McMaster-Carr. True, but not the same grade/material. See McMaster page 3394, exactly the same grade and material - Grade 25, 52100 steel. For example 100 1/4" balls from McM are $3.97 (p/n 9528K15), on ebay $9.99 (Item number: 4578478224). I stand corrected. I did a quick search and found the ones on page 3404. You would think that there would be more of a price difference between the two. I guess since 52100 is used for bearings, the quantities they are made in offsets the price for the extra precision. -- Dan |
"CAMCOMPCO" wrote in message oups.com... Hi all, Is there a way I can get a mirror like finish on a turned piece of metal? I know I can use 1000 grit and finer on a piece as it is chucked and turning in a lather, but how about the bored hole? How would I get a, say, 1/4" or 3/8" internal surface glass smooth? I am thinking of some sort of expanding reamer that I could put a 1000 grit wet/dry sheet around and insert it in the hole as it is turning...seems like I would just bunch up the paper though ;-) Anyone ever have to get something "barring" smooth internally....what did ya use? Thanks again gang....as always, any help is greatly appreciated John I haven't visited the newsgroup in quite a while, and you have probably already finished your project but here is how I would do it. I would use the same basic procedures that are used in making a custom rifle barrel. First drill the hole undersize, ream and polish for a good finish leaving the hole slightly undersize. Then silver solder a button (ball bearing) to the end of a rod that is smaller than the hole size. Using a good high pressure lubricant such a moly powder, or even anti-seize compound that contains a fair amount of copper I would push/pull the button through the barrel. Doing this with the hole about 0.005" undersize to start with should leave a good finish. Clean the inside to remove the moly or copper with a good penetrating oil (such as Kroil) and very mild soft abrasive such as "J-B Bore Compound". This is what is used by some shooters to clean the moly and brass from their rifle barrels, without causing any extra wear. The J-B is a soft vegetable based abrasive and will not remove any steel. |
In article , DoN. Nichols says...
The impression that I got was that the OD of the bearing was smaller than the ID of the bore, so it rolled around the bore as the workpiece rotated. And it seemed to me that the bearing was oversized by some amount for the hole, and it was a sort of dynamic ball burnishing effect. I would be interested to know the details of the operation because it sounds like it works pretty well. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
Thanks, project still in progress....it seems that alot of these
methods require making things a "normal" size...I gueass that's the key. If you wander out of "normal" you enter tha land of cutom tooling (cutum reamers....yikes). Thanks for the info... John |
Boring a super smooth surface
"Ned Simmons" wrote in message
... In article , spamto154 @comcast.net says... "DeepDiver" wrote in : Exactly right. Kind of a poor man's burnishing tool. Here's a guy on Ebay that sells gage balls (cheap): http://search.ebay.com/_W0QQsassZtoolsupplyQQhtZ-1 Nice find! But where are his metric-sized gage balls? :( Don't know, but he must have bought a dump truck full of "inch" sized ones at an auction or something. He's been selling them on ebay for some time now. Cheaper, and metric sizes as well, from McMaster-Carr. Ned Simmons Thanks Ned for the tip! |
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