Models for grinding HSS Lathe Tools

Wow this thread really kicked off. Is there a pic with all the models included? I forgot I actually had this great book on lathe tooling and function.
I highly recommend this book for anyone getting into lathes. It has numerous ways to ground tool bits for the lathes and some very good educational material for threads and other things. Great book for referencing.
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Hey Justin. Post 102 has pics and post 104 will tell you how to grind them.

You're right - the response to this thread has been amazing!
 
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Can we address belt grinders a little? I was thinking about adding a pyoceram platen to my grinder but I have a safety concern. I know how to secure them correctly but what happens if/when these things come loose? Has anyone had personal experience with this? Even with safety glasses I can envision shards of glass hitting my neck and face. Am I overestimating the risk?

I have a tool blank that is Rex 49. I have tried to grind it but the belt will not really make a dent. I am running 60 grit Zirconia at about 5000 SPFM. There is no way to grind this blank on my machine. Am I doing something wrong? Do I need higher SPFM?
Robert
 
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rwm said:
Can we address belt grinders a little? I was thinking about adding a pyoceram platen to my grinder but I have a safety concern. I know how to secure them correctly but what happens if/when these things come loose? Has anyone had personal experience with this? Even with safety glasses I can envision shards of glass hitting my neck and face. Am I overestimating the risk?
Click to expand...

I have had one Pyroceram liner come loose. My belt broke and knocked the liner loose and it fell and contacted my lower drive wheel. The liner itself did not crack or chip and since the belt had snapped, nothing was there to trap it. I did not have support screws or a ledge under the liner but this would have prevented it from dropping down. The JB Weld I used lasted over 10 years under pretty frequent use so I was happy with that product. My new liner does have two 6-32 SHCS underneath it and I used JB Weld again; so far, so good. I know of no way to guarantee a liner won't come loose. About all you can do is to make sure you have a support under the liner and use a good adhesive.

I have never ground a Rex 49 blank. I don't even know what the metallurgy is so I can't help here. Crucible's online info does not even list it. That said, I've not seen a HSS blank that a belt cannot cut. I've ground 8 and 10% cobalt bits with no issues so I'm not sure what is in that Rex 49 to make it so resistant. Does anyone else know what's in this stuff?

I wonder if a ceramic belt will cut it, Robert.
 
I don't know what the heck it is but it sure is hard! I ruined a belt already. These are high quality Zirconia belts from McMaster. At the rate I am going it would take over an hour to grind each facet of the tool.
I have ordered the ceramic belts you mentioned earlier. We shall see if that improves the cutting action.
I guess someone needs to produce a belt with PCD!
Thanks for your reply.
Robert

EDIT:
Oops...Triatic makes PCD belts if you want to pay for them! The 1 x 48 is $200. I wonder how long it would last?
R
 
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Robert
Are you sure on the Rex “49”?
There is no mention of a Rex 49 in this 400 pg book. It jumps from 45 to 54. Just trying to identify it for you.8F1F960C-9C7A-4C76-A614-44AE46ABD321.jpegF099C56C-C545-4C98-8C58-F2E2E52589C3.jpeg
 
I would just toss that bit and use one of known composition. An M2 or cobalt bit will cut almost anything we're likely to encounter, unless you're working with some unusual stuff.
 
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I am beginning to think this is of extraterrestrial origin...
Robert

EDIT:

Found this-
According to the Techstreet Store:
"Rex 49 is a high-speed tool steel designed to give much
longer life in machining difficult to cut materials such as
highly alloyed steels, stainless steels, superalloys and
titanium. Rex 49 heat treated to 67/69 Rockwell C makes
it outstanding for difficult machining operations."

"After much research, REX 49 chemical analysis % was
found within the pages of a declassified Federal Document:
Carbon - 1.10
Manganese - 0.45
Silicon - 0.30
Chrome - 4.25
Tungsten - 6.75
Molybdenum - 3.75
Vanadium - 2.0
Cobalt - 5.0"

Personally, I believe Crucible/Rex had a contract with the Federal Government that allowed them to reverse engineer materials from the fragments of crashed alien spacecraft.
R
 
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I asked my father ( retired Crucible sales rep of 30 yrs) and he wasn’t familiar with that number either. You might just be right on it’s origin.
 
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