Rex 49 tool bits information and comparison?

Blackrainstorm · Jun 21, 2019

I just bought some NOS Rex 49 lathe tool bits mostly out of curiosity and price/bit. Information online seems to be a bit sparse. About all I can find is that it seems to be equivalent-ish to AISI M41.

I would guess that, when compared to Rex AAA, it has higher red hardness and wear resistance, but a little less toughness?

Any other thoughts? It doesn’t appear that Crucible regularly produces 49 anymore—just obsolete or unpopular?

—David

Ox · Jun 21, 2019

Funny, the only "Rex" that I have ever known of is "76".
We wire form tools out of that stuff.

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Think Snow Eh!
Ox

iwananew10K · Jun 21, 2019

Good stuff, use it...for my use was dandy....I didn't worry about exactly what it compared to.....gotta grab the goods when you can.

I do seem to remember it ground easier than t15 but seemed to perform just as well on my old slow machines.

Matt_Maguire · Jun 21, 2019

Blackrainstorm said:
I just bought some NOS Rex 49 lathe tool bits mostly out of curiosity and price/bit. Information online seems to be a bit sparse.

Any other thoughts? It doesn’t appear that Crucible regularly produces 49 anymore—just obsolete or unpopular?

—David

I've never used it. My guess is it's just expensive having 5 rare element sweeteners mixed in. The only thing they point out in the data sheet is it's biased for abrasion resistance (pg.2). Attached stuff from the way-back files...

Good luck,
Matt

Blackrainstorm · Jun 21, 2019

Thanks for the link, Matt!

Kind of what I figured. It will be fun to experiment with at home, maybe on some aluminum or stainless. Though, I suppose I probably won’t notice too much of a difference against AAA, which I mostly have around.

Thanks,
David

Greg Menke · Jun 22, 2019

Checked my drawer, I found Rex MM, Rex AAA, Rexalloy, Rex Supercut. Being a garage hack they all seem to work equally well, though the Rexalloy and Supercut have a nice ground finish and are close dimensionally so are handy as spacers.

SAG 180 · Jun 23, 2019

Greg Menke said:
Checked my drawer, I found Rex MM, Rex AAA, Rexalloy, Rex Supercut. Being a garage hack they all seem to work equally well, though the Rexalloy and Supercut have a nice ground finish and are close dimensionally so are handy as spacers.

I eventually found a spec for some Rex MM I had: it turned out to be a World War 2 special formulated to substitute for harder to get alloying elements.

Edit:
Managed to find a description in a 1941 document:

"REX MM (5.50% W, 4.0% Mo, 4.0% Cr, 1.50% V, 0.80% C, balance Fe, is the general-purpose substitute for REX AA

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Rex 49 tool bits information and comparison?

Blackrainstorm

Aluminum

Ox

Diamond

iwananew10K

Diamond

Matt_Maguire

Stainless

Attachments

Blackrainstorm

Aluminum

Greg Menke

Diamond

SAG 180

Titanium