Fun with P20 tool steel

[cathead]

A friend of mine gave me a box of various tool steel leftovers from the tool and die shop where he worked. There
were several pieces of P20 tool steel just the right size for making tool holders for my C size Aloris tool post.
I did the milling with carbide cutters since it was somewhat hard material to machine. The 60 degree angles
were cut using a home made cutter made with a pair of triangular carbides. The interesting part came when
tapping the holes in the holder. It was tough going and broke off a tap in a hole that I had to drill out with
carbide. Other than that it went pretty well. Over the years I have made at least a dozen tool holders, all
of mild steel, which by the way have held up just fine for my use. So that's the story on P20 steel. In it's
unhardened condition, it has a Rockwell hardness of 30 to 32 which is where it can stay for this application.
It was a fun few hours in the shop making chips and turning a raw chunk into something useful.

I used a diamond flat lap to get some of the machining evidence to go away. Maybe sometime when I'm completely bored, I will go over it again
but for now it is good enough.

 

[T Bredehoft]

I had some 1.125 ETD-150 bar stock I made a bunch of AXA holders from. Its about like your P20, RC 28-32. Not "free machining" but workable with high speed. I made a few 5/16, a few 3/16, mostly 1/4" holders. They work well on my 1030 PM lathe. I avoided breaking any taps, lucky I guess. They look strange, being made from round stock, but they hold the tools well enough.

Edit: tweak dimension

 

[NC Rick]

A friend of mine gave me a box of various tool steel leftovers from the tool and die shop where he worked. There
were several pieces of P20 tool steel just the right size for making tool holders for my C size Aloris tool post.
I did the milling with carbide cutters since it was somewhat hard material to machine. The 60 degree angles
were cut using a home made cutter made with a pair of triangular carbides. The interesting part came when
tapping the holes in the holder. It was tough going and broke off a tap in a hole that I had to drill out with
carbide. Other than that it went pretty well. Over the years I have made at least a dozen tool holders, all
of mild steel, which by the way have held up just fine for my use. So that's the story on P20 steel. In it's
unhardened condition, it has a Rockwell hardness of 30 to 32 which is where it can stay for this application.
It was a fun few hours in the shop making chips and turning a raw chunk into something useful.View attachment 360526
View attachment 360527
I used a diamond flat lap to get some of the machining evidence to go away. Maybe sometime when I'm completely bored, I will go over it again
but for now it is good enough.

I really like steel something tough, hardish and durable can be made with. How‘s that stuff compared to 4140ph machining wise?

 

[T Bredehoft]

how's that stuff compared to 4140ph machining wise?

It probably machines the same, ETD (Electric (heat) Tempered and Drawn) and by the way ground to size) as opposed to unmachined steel. Same stuff, just finished differently. OH Yeah, tensile strength 150,000. I made hundreds of Piston Rods (non-automotive double ended pistons) from it.

 

[NC Rick]

It probably machines the same, ETD (Electric (heat) Tempered and Drawn) and by the way ground to size) as opposed to unmachined steel. Same stuff, just finished differently. OH Yeah, tensile strength 150,000. I made hundreds of Piston Rods (non-automotive double ended pistons) from it.

I get most of my steel from McMaste-Carr and the 4140 prehard comes mostly in ground stock, at least on two sides. I have been wondering about the p20 as (if I understand correctly ) it is designed for tool and die work. 4140 is used for tools but is tough for things like crankshafts, connecting rods and axles. I aint no metallurgist by any stretch of my imagination bit much of what i use those materials for are more like dies.

 

[benmychree]

It probably machines the same, ETD (Electric (heat) Tempered and Drawn) and by the way ground to size) as opposed to unmachined steel. Same stuff, just finished differently. OH Yeah, tensile strength 150,000. I made hundreds of Piston Rods (non-automotive double ended pistons) from it.

It has been my impression that ETD stood for "elevated temperature drawn"

 

[T Bredehoft]

It has been my impression that ETD stood for "elevated temperature drawn"

You're probably right, it was in 1980 that I was working it, memories fade.

 

[benmychree]

You're probably right, it was in 1980 that I was working it, memories fade.

I can testify, being 76 now, that memories can fade and it takes all too much time to recall things, especially names. Somewhere I have a brochure about ETD 150 that I've had since the 1960s. When I had my shop downtown, I kept some in stock for high stress jobs.