I wasn't sure what the purpose of the wheels was until the end of the video. I like it. I am curious though. Why did you not simply insert a couple of cheap bearings? Bearing steel is extremely high hardness.
Gday Alan, this is a great idea, very useful, like you say if you hard some real hard wheels you could reduce the diameter quite a bit, very handy if you where chasing a certain size with a polished like finish, thank you for sharing another great idea, Cheers Matty
Another idea would be to use the shanks of discarded end mills to make the rollers, pretty sure that would require a diamond drill though. Great demonstration!
The burnishing tool I made has ball bearings on it. Do not apply oil to the shaft. There is a limit to how much you can press or number of passes, as the material will work harden and start peeling off.
Alan, you could have case hardened your rollers. I know that I’ve been unsuccessful getting Casonite for this but have been successful using a mixture suggested by Clickspring. That was a good finish you produced but you would be confined to softer materials. Regards
A technique that does indeed need revisiting in the home shop, maybe not for everydsy use but a useful weapon in the machining aresenal. I found that one wheel was more than adequate if you have a narrow rimmed tyre of hardened alloy steel on a ball bearing. See my video from last year to see what I mean. I found the difference in size was in the order of microns but i started with a reasonably smooth finish even though for test purposes I was trying to get a rough one. If you junk your TC tooling and go for good old sharp HSS you should be easily capable of turning to sub thou dimensions with the right technique.
Nice one, Alan. Burnishing is a technique that deserves more coverage than it has previously received. I like the design of that clamp knurler you use here. It is a compact and tidy assembly. Any particular brand name on it?
You can get a much better surface finish by using a single roller with a curved surface and preferably of stainless steel. The pressure exerted on the piece should be depended on the initial surface roughnes and the speed of the item and the feed of the roller should be just enough for squashing the asperities of the turned surface. Excessive pressure will end up giving you a bad surface.
Question, not a criticism: would oil not help (the already good burnished) surface finish? Or were you just looking for a reduction in size? Interesting video, as always.
Mathew, the ball bearings are used as the burnishing rollers. The inner race is clamped stationery whilst the outer race makes rolling contact with the workpiece and effects the burnishing operation. If rollers with the exact inside diameter required to fit the knurler pins can't be obtained then fitting bushing sleeves to the inner bearing race is a viable alternative.
I wasn't sure what the purpose of the wheels was until the end of the video. I like it. I am curious though. Why did you not simply insert a couple of cheap bearings? Bearing steel is extremely high hardness.
Very informative. Never have seen this before. Great idea for mild steel also. Thanks, Tom
Gday Alan, this is a great idea, very useful, like you say if you hard some real hard wheels you could reduce the diameter quite a bit, very handy if you where chasing a certain size with a polished like finish, thank you for sharing another great idea, Cheers Matty
Useful tip, Capstan lathes used burnishing rollers on many parts, I had forgotten this feature.
Thanks for sharing.
It's also great for making a bearing surface, as in a plain bearing with a bronze bushing.
Thanks Alan. Interesting as always.
Another idea would be to use the shanks of discarded end mills to make the rollers, pretty sure that would require a diamond drill though. Great demonstration!
The burnishing tool I made has ball bearings on it. Do not apply oil to the shaft. There is a limit to how much you can press or number of passes, as the material will work harden and start peeling off.
Been on a dumpster site today.
Saw roller valve lifters, the roller sits pretty tight. One could use that to experiment with burnishing.
good idea
Alan, you could have case hardened your rollers. I know that I’ve been unsuccessful getting Casonite for this but have been successful using a mixture suggested by Clickspring. That was a good finish you produced but you would be confined to softer materials. Regards
A technique that does indeed need revisiting in the home shop, maybe not for everydsy use but a useful weapon in the machining aresenal.
I found that one wheel was more than adequate if you have a narrow rimmed tyre of hardened alloy steel on a ball bearing. See my video from last year to see what I mean.
I found the difference in size was in the order of microns but i started with a reasonably smooth finish even though for test purposes I was trying to get a rough one.
If you junk your TC tooling and go for good old sharp HSS you should be easily capable of turning to sub thou dimensions with the right technique.
Nice one, Alan. Burnishing is a technique that deserves more coverage than it has previously received. I like the design of that clamp knurler you use here. It is a compact and tidy assembly. Any particular brand name on it?
Hi Howard the only name on it is brighouse ltd I think they are over 50 years old.
You can get a much better surface finish by using a single roller with a curved surface and preferably of stainless steel. The pressure exerted on the piece should be depended on the initial surface roughnes and the speed of the item and the feed of the roller should be just enough for squashing the asperities of the turned surface. Excessive pressure will end up giving you a bad surface.
Question, not a criticism: would oil not help (the already good burnished) surface finish? Or were you just looking for a reduction in size? Interesting video, as always.
Hi Ian
Yes you could use some oil but if any bits stick to the oil they will be crushed into the surface
How would a pair of bearings work as burnishing wheels?
Hi Matthew if you can find the correct size with seals they should work ok
Mathew, the ball bearings are used as the burnishing rollers. The inner race is clamped stationery whilst the outer race makes rolling contact with the workpiece and effects the burnishing operation. If rollers with the exact inside diameter required to fit the knurler pins can't be obtained then fitting bushing sleeves to the inner bearing race is a viable alternative.