What material for boring bar bushing?

turnworks · Nov 29, 2019

Making some simple split bushings to go from 3/4" down to 3/8" for a a boring bar and small ID threading tool.

I don't think it matters much but was curious what would you pick for the material. My first choice was A2 annealed because I have it on hand but then I thought maybe cast iron would be better.

With the small 3/8" size I won't be feeding it hard but if bushing material will make any difference in harmonics might as well get the right one now. The boring bar is heavy metal if that makes a difference.

Anyone ever seen a difference in harmonics with using something other than mild steel or A2 for a split bushing?

Thanks for your time.

rogertoolmaker · Nov 29, 2019

Boring Bar Bushing Material

turnworks said:
Making some simple split bushings to go from 3/4" down to 3/8" for a a boring bar and small ID threading tool.

I don't think it matters much but was curious what would you pick for the material. My first choice was A2 annealed because I have it on hand but then I thought maybe cast iron would be better.

With the small 3/8" size I won't be feeding it hard but if bushing material will make any difference in harmonics might as well get the right one now. The boring bar is heavy metal if that makes a difference.

Anyone ever seen a difference in harmonics with using something other than mild steel or A2 for a split bushing?

Thanks for your time.

It looks like your trying to over engineer. Just use low carbon steel SAE 1020 or better yet 12L17. Using A2 is a waste of high quality heat treatable tool steel. I'll assume if you have A2 in the shop you'll have some low carbon steel bar laying around the shop.

Why are you concerned about harmonics? If your having trouble with chatter; re-sharpen the cutting tool to reduce the rake and/or use correct speeds and feeds.

Roger

Cole2534 · Nov 29, 2019

Ive used 6061 to go from 1/2" to 3/8" in a Criterion 202, it worked fine.

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thermite · Nov 30, 2019

turnworks said:
Making some simple split bushings to go from 3/4" down to 3/8" for a a boring bar and small ID threading tool.

I don't think it matters much but was curious what would you pick for the material. My first choice was A2 annealed because I have it on hand but then I thought maybe cast iron would be better.

With the small 3/8" size I won't be feeding it hard but if bushing material will make any difference in harmonics might as well get the right one now. The boring bar is heavy metal if that makes a difference.

Anyone ever seen a difference in harmonics with using something other than mild steel or A2 for a split bushing?

Thanks for your time.

All manner of s**t can contribute to chatter. Bushing alloy ain't never even been on my list.

If set up to use salvaged eBay factory-mades surplused off dead turret-holers, expect spring steel, 'coz they were meant for long life and ease of clamp and release to not waste time.

Onesies or fewsies, DIY, that size? Even a salvaged old carriage bolt or cut-off length of various of the cheapaxle tribe can serve for project-metal.

Aside "the good stuff" for projects as need hardened and drawn.

Not so much because it costs the very Earth. Because when you NEED it you NEED it, not two days later off MMC or such.

2CW

turnworks · Nov 30, 2019

Thanks for the reply. Mild steel it is for the bushings. I do at times over think things. Im swapping from ER holders to these bushings for more clearance and just didn't want to leave anything on the table if a certain material is generally better.

thermite · Nov 30, 2019

turnworks said:
Thanks for the reply. Mild steel it is for the bushings. I do at times over think things. Im swapping from ER holders to these bushings for more clearance and just didn't want to leave anything on the table if a certain material is generally better.

LOL! Shop foreman onct made a teeny-tiny bushing out of 14 KT Gold.

For temporary. It went off to the refiner onct no longer needed.

Good choice of alloy? Not really. POOR one, actually.

But it was a joolry manufacturing shop. It was what we had HANDY and had the tools to actually work with!

10K white wudda been stiffer. But 10K is less than 50% Gold, so it weren't even allowed in the door atall any more than silver or plated goods, that grade of fac'try. Daren't risk degrading contamination or swap-about shenaningans.

Needed anything in steel we couldn't just ORDER, I'd do those to home for the next day's use, best-case.

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What material for boring bar bushing?

turnworks

Cast Iron

rogertoolmaker

Cast Iron

Cole2534

Diamond

thermite

Diamond

turnworks

Cast Iron

thermite

Diamond

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