You sure can! I've done this plenty of times.

Cheaper holders will be easier than high end ones though.

Jim

Hi Dave,

On the few holders I have come across I was able to mill the holder down using a carbide tipped cutter, would probably be possible with a HSS cutter but the edge might need grinding afterwards.

Thor

The cheap ones I've had aren't very hard they are no harder than say a high tensile steel bolt.

I always try to buy 20mm holders and then mill them down to 18.53mm which is the exact height of the Smart & Brown model A which I use.

I have milled down at least 25 down, including Kennametal, Stellram, Sandvik, Iscar, Korloy, Seco, and others including Chinese, and they are all similar hardness. I use a Ceratizit 50mm shell mill with 5 RPHT12 inserts in it. The inserts can be indexed six times per set, and milling down just one tool uses up an index.

If you only have hss, then keep a good flow of coolant and use a very slow speed.

I bought an inexpensive set of 10mm insert tool holders from Aliexpress. They were a bit tough to machine down to 3/8" to fit the Myford using HSS in the lathe, holding the tool holder in the four jaw chuck. HSS tool kept skidding over the surface instead of cutting.

Carbide end mill whizzed through it like cheese, holding the cutter in the lathe chuck and mounting the tool holders in the toolpost.

So, harder than mild steel but not super hard, but certainly a bit tough.

Yes agreed. The cheap ones are quite easy but I had to use a carbide mill to cut down a Sandvik holder for a mate. Tough going but I got through it.

I have on order from China a 25 X 25 toolholder for 22 size carbide threading inserts. The 20mm holders only go up to the 16 size. So I will have to reduce the height by 6.47mm to fit the lathe, I'm not looking forward to doing it.

Dave, your carbides must be made from HTC (high tensile cheese) bin them now.