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Al2O3 is a hard, white material used for making firebricks and numerous molded ceramic parts.

Say I had a firebrick, took a core out of it using a thick-walled diamond hole saw and a drill press.

What lathe insert material would I then use to machine the outside of the Al2O3 cylinder assuming I could take care of all the holes using diamond hole saws?

My budget for one cutting bit would be $500. But that would take me many hours of work to raise, so I prefer something less expensive, since I'm probably going to break it, hence cost effective.

Air
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Daniel Donnelly
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1 Answers1

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In industrial applications probably the closest approximation is in dressing bonded abrasive wheels. These use abrasive particles including aluminum oxide but a different bonding medium which makes them a bit tougher than standard fire bricks. With this is mind a diamond tipped dressing tool would probably be a good thing to try.

I lathe turning stone scrapers are widely used. In this case a tough, abrasion resistant tool steel would probably be the best bet perhaps something like D2.

Similarly for turning it is probably well worth sawing the outside to a hex shape to get the section closer to round before you start.

Another approach would be to use a belt linisher with a coarse ceramic belt and a cylindrical grinding jig.

Of course if you just want a simple cylinder it would be logical to use core drills for both the inside and outside. In this case you might want to pre drill a pilot hole in the centre and fit a metal sleeve and use a plain pin instead of the pilot drill in the arbour.

Another big consideration is dust extraction to protect both the machine tool and your lungs a firebrick dust will wreak havoc on both.

Chris Johns
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