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MGREEN
05-20-2008, 09:46 PM
I was trying to cut off a small lump of tool steel with a Dremel,
barely getting any depth, and was blowing up the thin cut off
discs way more than usual.

I have this 3/8'x3/8"x3" long tool steel blank but I dont know
what it actually is.
The blank is marked...REX 95.

Anyone know just what this steel is?

Also, since I cant seem to keep my hands steady enough,
I plan to make a stub arbor to mount to the Foley-Belsaw
tool and cutter grinder spindle which will hold the tiny Dremel
cut off discs, and make use of the sliding table so I can cut
small lumps off and braze them onto boring bars and internal
threading tools that I would like to make.
Mike Green

rkepler
05-20-2008, 10:00 PM
That's a prehardened tool steel bit for use in a lathe. Normally you'd simply grind it to the form needed and cut with it, but to cut pieces off you can grind a groove all the way around, clamp it in a vise with the groove just above the jaws and smack it sideways with a hammer. Keep a shop rag over it, it'll stop it from flying too far and will help keep fragments of the bit from your eyes.

miker
05-20-2008, 10:54 PM
There is some info about the make up of the steel here:

http://www.crucibleservice.com/eselector/prodbyapp/highspeed/rex95.html

Is it possible to Braze HSS?

I wouldn't mind trying to make a small boring bar with maybe 3/16 round HSS poked through a round hole in the bar and brazed.

Rgds

Lew Hartswick
05-20-2008, 10:55 PM
You mean something like this?

http://i233.photobucket.com/albums/ee238/LewHartswick/1cutteroverall.jpg

http://i233.photobucket.com/albums/ee238/LewHartswick/2closeup.jpg

http://i233.photobucket.com/albums/ee238/LewHartswick/3closer.jpg

...lew...

rolland
05-20-2008, 11:04 PM
For what its worth. If you will soak the Dremel cutoff blades with super glue before you use them they will last a lot longer, don't pick up the blade to move it right after you glue them (don't ask me how I know):o
They also make a thicker blade and some that are reinforced with mesh that works much better than the thin ones but the glue really helps a lot.

MGREEN
05-21-2008, 12:51 AM
rkepler,
Sorry I wasn't clear, I knew it was a lathe tool bit blank, I just didn't know if was HSS or high carbon or whatever. Haven't tried to score and then whack
to yield a small chunk does it typically snap clean?

miker,
Thanks for the link, I've added it to my favorites.
Also in the past I have silver soldered HSS to mild steel
and it seems to work just fine.

Lew,
Thats exactly the kind of thing I was thinking of, very cool!
Since I have the foley on hand, see here http://bbs.homeshopmachinist.net/showthread.php?t=28964
I figured that with a short arbor of some kind that I would
make up to fit, that it would do the job.
I do like what you have for a cut off wheel, where could one obtain such wheels?

Rolland,
Also never squeeze a bottle of CA glue while pionted at your face,
as a friend inadvertantly did once, squirting the glue right onto his tounge and lips, and had to keep his mouth open and lips apart for a while until the glue set and then was able to PEEL it off...OUCH....
I laughed my ass off when told me about that one, and so did he.
Mike

pcarpenter
05-21-2008, 05:39 PM
You do want to be careful as I thought I understood that CA glue when heated formed something toxic?? Its sure to burn in that grinding wheel application.

I never buy those crappy, unreinforced cut off disks. They are an exercise in frustration. You can move them laterally (very gently) in the groove to create more of a kerf that will reduce biding, but at some point, sooner or later, it will grab and just shatter.

The reinforced disks are well worth the cost. They are most commonly available in a package that only holds maybe a half-dozen, but I would predict that will outlast a tube of the others. The only downside is the kerf is larger.

I have found off-brands of similar disks at places like gun shows, hobby shops etc. Some are quite a bit bigger. Remember that its the tangential velocity that the work sees, so run the larger ones at a smaller RPM to keep them safe....and they will still get the job done.

I would agree though that the best way may be to score and snap. Figure on some cleanup afterwards...and yes, you can braze it on. Most HSS will not loose its hardness up to at least a dull red from what I understand, and you should be able to silver solder below that point.

BTW--Evan mentioned some sort of ceramic cutoff disk and a mini-chop saw type tool that uses them. I suppose they come from some supplier like his wife:D but I would love to find one of those just for slicing up HSS.

Paul