Burnishing tool

[jimmy bParticipant @jimmyb]

I’ve ordered a diamond burnisher and holder, inspired by this thread.

Having watched a few videos on the ball bearing type, I can see the benefits, but will stick with what I have used in industry, not sure how well this will work on a manual lathe, but only one way to find out!

 

Jimb

[Neil LickfoldParticipant @neillickfold44316]

I made a couple of ball burnishers with 5/32 Ceramic bearing ball pressed into a piece of 12mm 4340 bar. They work OK, but on the Myford, it was too much area area .
So made another with a 1/16 Ceramic bearing ball. On the Myford that works a lot better. Burnishing the 4340, it was very difficult to reduce the size by less than 0.01mm on diameter. I think all that was happening is the machine and part were just flexing. With the 1/16 ball, I was easily able to burnish and make the diameter smaller by 0.01mm and gave a nice finish.

I too have ordered a R1.0 polished diamond tool. Will make the holder for it.

My testing was all on 4340 bar, the reference diameter used to trim the diameter back after the ball was pressed in. Then I turned back to within 0.2mm of the ball centre line for the 5/32 ball and 0.1mm for the 1/16 ball. The smaller one will get a blade like configuration to see if I can burnish a shoulder and a diameter.

Just using cutting oil, Blaser CF35, at 600 odd rpm, everything stayed cool the whole time. I guess a big part must be the highly polished surface of the Ceramic bearing ball.

Neil

[Neil LickfoldParticipant @neillickfold44316]

<p style=”text-align: left;”>Pictures.</p>

[Neil LickfoldParticipant @neillickfold44316]

The ist picture and the last picture are the same tool that was burnished with the 5/32 tool shown in the 2nd picture. That same tool in the 2nd picture also burnished the 1/16 ceramic ball holder.

The middle picture is showing the finish from the 1/16 ceramic ball burnishing the reference diameter of the 1st tool made. The 1/16 ball was much better than the 5/32 ball it seems to me.

All 3 holders have the ceramic ball just pressed into the end of the bored steel.

Neil

edit, looking at the photo’s , you can see that I have not cleaned off the oil very well. The taper was done a bit free hand and some from an old 45 chamfer tool. They can all be made pretty now that I know that it works really well.

Will try them on other materials that are softer like free cutting MS and Aluminium etc.

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