Milling 01 tool steel

[RayG]

Hi All,

I'm making some gunstock checkering tools for a friend, these are similar to a woodworking float, in the sense that they have a series of 60 degree grooves, forming the teeth, the rake angle of the front of the tooth is negative 10 degrees, a bit like the rake on a crosscut saw. (The plane makers floats I've seen mostly have a positive rake on the teeth.)

The problem I'm having is that the 01 steel is hardening as I'm milling it and I'm chipping the points off the 60 degree dovetail cutter which leaves the gullets badly shaped, so far I've tried keeping the coolant up as much as I can, doing fast shallow cuts, and slow cuts. but whatever I try, the stuff keeps hardening.. so hard that a file just skates off, and chips the points on the HSS cutter...

I'm starting to think I should be looking at CBN or diamond wheels...:)

Anyone have experience milling 01 tool steel?

And before anyone asks, yes it is in it's annealed state (before I start at least!)

Regards
Ray

[BobL]

Ray - look here (http://www.woodworkforums.com/f44/floats-66551/).

Some questions:
Where did your O1 come from?
How did you anneal it?
What cutter RPM are you using?
What cutter feed speed are you using?

[RayG]

Hi BobL,

Thanks for the reply, I'm hoping you can point me in the right direction..

I remember looking at your floats a while back, and it's been in the back of my mind to make some.

The 01 is from these guys... Precision Ground O1 Oil Hardening Flat Ground Stock (http://www.victornet.com/report/Flat-Ground-Stock-9-64-quot-to-1-4-quot-thick-/90.html) The freight is a killer! but I only need small bits of it.

It already comes in annealed form, and files nicely, although I am going to have to re-anneal the stuff that has hardened during milling.

I'm running at 1600 rpm with an 1 3/8 HSS dovetail cutter, I've tried feed rates from over a minute per 50mm pass to 15-20 seconds per 50mm pass..


Here's a picture, it's a bit hard to see but the sharp tips of the dovetail cutter have broken off, and the gullets are badly shaped..
I might be able to re-anneal and file them.. still pondering..

http://www.backsaw.net/pics/GunstockCheckering.jpg

Regards
Ray

[Stustoys]

1600rpm?
160?
my maths says 145rpm, but I'm checking it again
Stuart

[RayG]

Hi Stuart,

You are spot on. :2tsup:

I resharpened the cutter and ran it at 150rpm, worked a treat, no work hardening or chipped points....

Thanks, (I would have probably woken up eventually)

Regards
Ray

[Stustoys]

glad I could help :)

Stuart

[BobL]

Good to hear you have it sorted.

[old_fella]

Dont think i would even run a carbide at 1600 rpm, hss cutting formula is 300 xV/ D and mild steel V= 30 so with tool steel it would be lower again