Those Cheap Diamond Inserts

That's true, but I did run across a reference (Stefan Gotteswinter video maybe) to an actual diamond attached to a tool. There are also coatings that are called diamond, although most are actually DLC "diamond like coatings."

Diamond wheels are available for a lot of things. Yes, you can freehand grind on a diamond wheel. A buddy of mine sells tungsten grinding kits for various grinders that include adapters, and a cheap diamond coated wheel he buys in bulk from China. He sells them to welders for shaping tungsten electrodes. I have one of his cheap wheels and I sometimes use it to rough finish the edge on a tool before honing on a bench stone or lapping stick.

I have a whole bucket (smallish) of broken and worn out carbide mills I save for making specialty tools. When I needed a special 7 degree dovetail cutter to make a tool holder I ground one of an old carbide end mill. Okay. I cheated. I cut the 7 degree cutting edge on a tool and cutter grinder with a diamond wheel, but other edges and clearances I just ground freehand.

PCD diamond turning inserts are actually quite common. They are mostly made from natural diamonds, sometimes synthetic. There is another kind whose name I have forgotten which is even more diamond-y, though still not a single diamond.

PCD inserts (or better CBN ones if machining steels) made for aluminium can be of use to hobby people if careful; being sharper then ones made for harder stuff they will cut with less force, useful on smaller less powerful machines.

Recommended only once you have learned how to use inserts without chipping them!

SPD single point diamond turning tools (which are single diamonds) are often used in CNC machines for optical moulds and lenses. The finish is used as-is, no polishing!!!

Sometimes used for high-accuracy machining of copper and copper alloys too.

When air bearings aren't smooth enough ..

I have a 1/2 carat single diamond tool for truing grinding wheels. Cost about £!5 iirc, but that was a while ago. Hmm, still £14.99 on ebay.

CVD chemical vapour deposition diamonds are frequently grown on tooling surfaces; they are real diamonds, though not single diamonds when grown on surfaces.

They are sometimes made into blocks in a nickel or cobalt matrix, as found on circular saw blades and polishing disks, though often natural diamonds are cheaper.

Peter Fairbrother

That's true, but I did run across a reference (Stefan Gotteswinter video maybe) to an actual diamond attached to a tool. There are also coatings that are called diamond, although most are actually DLC "diamond like coatings." Bob La Londe

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I've watched an optical lathe turn a Germanium lens for a military vehicle thermal imager with a clear single crystal diamond bit with the geometry of brazed carbide. It may have been synthetic, the laser diodes I had for the inter-satellite communications project were mounted on thin sheets of artificial diamond on a gold-plated copper heatsink. Diamond is an excellent conductor of heat but an electrical insulator.

On Tue, 20 Aug 2024 16:48:55 +0100, David Billington snipped-for-privacy@invalid.com wrote as underneath :

Thanks David, I re-read that post but have never come across the inserts he is talking about so I was looking for a link to clarify myself! C+

On Tue, 20 Aug 2024 18:17:05 +0100, Peter Fairbrother snipped-for-privacy@tsto.co.uk>

wrote as underneath :

Thanks Peter for all the detail, I'm better informed now, aprecciated. C+