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View Full Version : Grind below scale: What type of material is it?



chipmaker4130
11-11-2012, 12:18 AM
One more question from my recent acuisition: There are a number of cutoff blades and square tool blanks which are black. Some of them are marked REX aaa like many bright hss blanks, some are not but all say 'grind at least 1/32" below scale'. They spark like hss on the grinder, but are they hss? Some also say 'grind slowly - do not quench in water'.

Also, there are three new cutoff blades with a silver-soldered cutting lip that does not look like carbide (but maybe it is). Anyone familiar with these?
http://i156.photobucket.com/albums/t18/chipmaker4130/PartToolSpecs.jpg
http://i156.photobucket.com/albums/t18/chipmaker4130/2PcPartingTool.jpg

RussZHC
11-11-2012, 12:38 AM
Generally speaking, yes, HSS BUT...you can dig some more, I don't have the info at my fingertips but Rex AAA is certainly several "steps" above generic M2 HSS.

It is what you think, the scale is left from processing...as well, the "don't quench in water" is to, potentially, not have micro cracking from the heat/cooling "shock". My understanding is the way this material is processed it is susceptible to such cracking but not much else...very good ability to cut while red hot etc. "Rex" comes in a variety of flavors, "AAA", "AA", "95" and others

Edit: I may be "wrong" in comparing it to HSS because one may not consider cast alloy as "high speed steel"...not sure why but there is a difference. They can look pretty sad, until you get past the external look...

Found this link awhile ago http://conradhoffman.com/stellite.htm talks a lot about cast alloy lathe tool bits, Stellite (sp?) will come up in the discussion, to my knowledge that is an actual brand (or type from a specific company) but is sort of interchangeable when talking about the group of products in general (Kleenex v tissue)

If you have some, great...I am not sure I would pursue them for home use, new they are not cheap.

Edit II: as other posters have said...don't be put off by the unfinished look...I've got some cast bits that have a mirror like polish on them, others that look like very poor castings (but they also don't feel the same, often, to me, heavier for the same size). That said, if you purchase a box full of stuff and some is really old, it could also be carbon steel i.e. pre HSS in common use days...the exterior look is quite similar

Toolguy
11-11-2012, 12:41 AM
Also, the ones that say don't quench may be Tantung G. That is one of the materials they used for tough jobs before carbide.

JRouche
11-11-2012, 12:50 AM
Hmm? That second pic doesnt look like carbide. Im not sure what the blades you have are. But after some looking Vascoloy-Ramet seems to be an old company that did in fact deal with carbide. I wounder if you have some first run "blanks" that were not run though the final finishing operation. Like the final grinding station before they were sent out as finished pieces. I also have a stack of HSS tool bits that are marked REX and have not got around to using them.

So... The grind instructions you have is interesting. The "grind at least 1/32" below scale". What does that mean is prolly what you want to know right? Im interested also. I have about 20 pounds of new blanks of similar HSS blanks. And most of it is the ground bright metal thats common with HSS. But several bits are dark, basically black and NOT ground, almost a cast finish. They look like cheap steel but Im sure they are not, just old and a diff manufacturing or sales process. They have what looks like cast in depressions with various identifiers in the cast pocket.

I could post up some pics if you are interested. Im looking forward to hearing what the old heads in the know come up with. This site has a WEALTH of knowledge. One of the reasons I love this site. Besides the fact that you can ask ANY question without getting hammered with condescending responses. Its nice to be able to ask a simple Q and not get talked down to.

Love me some HSM forum peeps!!!! JR

oldtiffie
11-11-2012, 01:13 AM
http://www.google.com.au/#hl=en&rlz=1R2IRFC_enAU360&sclient=psy-ab&q=rex+aaa+tool+bits&rlz=1R2IRFC_enAU360&oq=Rex+aaa&gs_l=hp.1.2.0l2j0i30l2.2699.5913.0.10566.7.7.0.0.0 .0.406.2177.2-4j2j1.7.0.les%3B..0.0...1c.1.EwmVPkgag7w&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=be8304172aae4a7d&bpcl=38093640&biw=1920&bih=884

With that much material to remove I'd be looking for someone with a "Blanchard" grinder to rip it off.

Failing that and given that I am satisfied with the HSS cutters I have, I'd either refuse it or "bin" it.

Jaakko Fagerlund
11-11-2012, 03:26 AM
With that much material to remove I'd be looking for someone with a "Blanchard" grinder to rip it off.
Huh? 0.8 mm goes quickly in a surface grinder, especially if the material width is less than the wheel as then you can just plunge cut it. Probably takes under a minute or two, if counting the setup time.

oldtiffie
11-11-2012, 03:34 AM
True for an experiencd surface grinder operator but a full width plunge cut (needs coolant) without the correct wheel and proper "stops" on a good magnetic chuck is just an accident waiting to happen for anyone - especially a learner.

I'd still refuse or "bin it" as the risk versus benefit may just simply not be worth it.

Rustybolt
11-11-2012, 11:04 AM
Also, the ones that say don't quench may be Tantung G. That is one of the materials they used for tough jobs before carbide.


Or possibly stellite?

chorne27983
11-11-2012, 11:04 AM
When you grind your cutting edge and relief angles on the HSS you will already be below the 1/32" and it isn't like you have to grind the whole blank so I don't see why you would want or need to use a surface or blanchard grinder.

Toolguy
11-11-2012, 11:37 AM
It could be Stellite also. At any rate, use it or give it to someone who will. That is the premium grade good stuff.

Blackadder
11-11-2012, 02:41 PM
grind below scale is for the work not the tool

think a cast iron casting the scale will take the edge off a HSS tool bit in the days before carbide tools were common that was the standard practice to prolong the tool life

Stuart

RussZHC
11-11-2012, 03:30 PM
http://bbs.homeshopmachinist.net/threads/18714-Anyone-use-stellite-anymore

Stuart: not disagreeing, what you say is very true...I have however seen photos of lathe bits that are almost not finished i.e. I would debate if they were entirely square, certainly not the ground finish one comes to expect
Bit of an aside, I am always amazed that, as example, something can work so well at such temperatures yet in other ways be so "weak" re: quenching and interrupted cuts

oldtiffie
11-11-2012, 05:25 PM
When you grind your cutting edge and relief angles on the HSS you will already be below the 1/32" and it isn't like you have to grind the whole blank so I don't see why you would want or need to use a surface or blanchard grinder.

That's true enough.

But I was referring to "plunge" cutting on a surface grinder versus getting it done on a "Blanchard" grinder (both "all round").

Everybody (mostly) was only guessing as to what it was/is and even though I don't like and won't have "unknown" cutting tools and not-with-standing that I'd tracked it down on Google, I'd still reject it for the reasons given.

http://www.google.com.au/#hl=en&rlz=1R2IRFC_enAU360&sclient=psy-ab&q=rex+aaa+tool+bits&rlz=1R2IRFC_enAU360&oq=Rex+aaa&gs_l=hp.1.2.0l2j0i30l2.2699.5913.0.10566.7.7.0.0.0 .0.406.2177.2-4j2j1.7.0.les%3B..0.0...1c.1.EwmVPkgag7w&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=be8304172aae4a7d&bpcl=38093640&biw=1920&bih=884

I don't dispute others different opinions.

willmac
11-11-2012, 06:34 PM
The Blanchard grinders I have seen are massively out of scale for grinding tool bits. I'm not saying you couldn't do it that way, but it would be a bit odd. Perhaps you have in mind a swing arm grinder? Even then I'm not sure why you want want to use one of them instead of an ordinary surface grinder. Why do you think this is problematic? I have ground small parts like this many times on a surface grinder.

Duffy
11-12-2012, 12:37 AM
I have a bunch of REX aaa blanks in plain black finish. I grind them just like any other cutter and they perform just fine. They are a product of Colt Industries and I believe that they are a cobalt alloy. I quench them in water but, since I grind them freehand, I quench them when they are ALMOST too hot to hold. I very much doubt that they are hot enough to undergo micro-cracking.
The fact that they arent shiney does not seem to matter much; they ARE square, just black.

chipmaker4130
11-12-2012, 12:46 AM
Thanks, Duffy. That's the way I plan on using them too.