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What CPM stock for lathe cutters?

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  • What CPM stock for lathe cutters?

    Just a little background first... a little familiar with CPM-3V and CPM-M4 / Bohler S690 used for some plane iron and chisel stock with woodworking tools. Thoroughly happy/impressed with the results of using them.

    So, this led me here where I hope someone has a little experience/advice regarding which "blend" I should be looking for. Vaguely remember reading somewhere that with steel cutting vs cutting wood, that cobalt should be included for heat resistance, longer edge life. I know that whatever I end up with will need to be sent out for heat treat, and there is no pressing timeline looming with this... just out to satisfy my curiosity.

    Thanks for any input...

  • #2
    I've used M4 blanks for special forms for years in different toolsteel alloys without a complaint. It is a good alloy combining toughness with workability. They hold up fine as long as you keep the RPM's where they should be & provide oil or coolant. There are several alloys steels available for cutters, but keep in mind that the trickier you get on the choice of steel, the more difficult it will be to grind them. T15 comes to mind. It's just a real SOB to grind, even using a surface grinder & a good wheel such as a Norton SG. It's tough enough that you can actually feel the wheel "skate" across the material through the handwheels. Nothing wrong with experimenting, but I'd recommend that you keep notes if you do. I think you'll find that the M4 provides 85%+ performance of the others available in steel turning applications.

    P.S. If I had to grind any quantity to speak of regarding T15 again, I'd probably just send it out for wire EDMing instead.
    Last edited by toolmaker35; 05-06-2012, 06:27 AM.


    • #3
      Thanks for the info and link toolmaker35, think it very well may have been CPM® REX® T15 on the page you linked to. I'll look around for some of it in 1/2" square stock then. The other CPM stuff I've worked with is pretty mild to grind on the belt grinder unless you get it too hot, then it'll pluck the abrasives clean off the belt if you're not careful.

      I know alpahknifesupply sells a bit of the other stuff but not T15. Any ideas where I might find some 1/2" stock?

      Thanks again...


      • #4
        Glad to help. Crucible lists some pre-hardened & ground tool blanks, but I haven't seen a distributer for these...

        I found this supplier using Google, but have no prior dealings with them. They do show as having no minimum on orders, so it may be worth an email or phonecall...

        Our shop had used Crucible in the past, and then we recently got away from using Alro, so I'm not sure who we're getting our steel from now. Considering our volume, probably from another major outfit (with discounts for volume).