lathe tool milling question

oughtsix

oughtsix

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Newbie question here- Can I or how do I mill a hss lathe tool. I have made an attempt, but my hss mill cutter doesnt mill the tool steel very well. I need a square thread tool that is .040 wide. I have ground a few that mic'd out to .040 +/-, but my rolling block action won't screw on. And if the cutter is too long (deep?) it has a tendency to break, I've broken a bunch. Hopefully there is a simple way to make the thread cutter. Remington must have had a good one to do all the barrels they made.


Thanks,

-06
 
sssfox, So far that's what I have figured out. Hoping there is a trick out there some where

Thanks

-06
 
I cant imagine milling HSS - in any conventional manner that Im familiar with, now rigging up one of the many varieties of stones and grinding a cutter...that shouldnt be so hard.
 
Oughtsix

I agree with the grinding concept. If you can, avoid sharp corners where the thresd shape meets the main cutter body. In the engineering books a small radius prevents concentrated force build up in these corners. I believe Allis Chalmers found this to be true on their crankshafts where the connecting rod journal met the crankshaft throws.

Good luck.

Ray
 
You can mill HSS, but you need either a CBN tool, or specialized carbide meant for machining hard material. A lathe tool bit is probably going to be in the high 50s to 60 HRC. That's not trivial. Grinding is much more practical.

You might try roughing out the shape on the grinder so that is slightly over, and then get a diamond needle file, or a small diamond hand lap, and finish up that way. The hand lap will probably give you a better finish. Just use plenty of water to clear the dust, and it should go pretty fast.
 
06 I dont think you will be able to mill your threading tool with what you have available.
oughtsix said:
....And if the cutter is too long (deep?) it has a tendency to break...
Click to expand...

Are you grinding relief on the sides of the tool? If you are trying to make it parallel then it will rub on the sides and possibly (probably) lead to breakage.

Cheers Phil
 
I've milled HSS toolbits quite often in making step gages and other gages for checking tooling. You can only take a thou or two at a time. And chances are, once you are done, so it the tool. Any gage though I have always roughed in with a carbide tool and always finished off by precision grinding. But there is NO WAY HSS is going to cut HSS.
 
Thanks for the info and ideas. Looks like I am back to grinding and filing. I guess once I get this square thing figured out I'll be pretty knowledgeable about what not to do. Experience is always the best teacher. Some day I hope to start posting photos of the project.

Thanks again,

-06
 
oughtsix said:
Thanks for the info and ideas. Looks like I am back to grinding and filing. I guess once I get this square thing figured out I'll be pretty knowledgeable about what not to do. Experience is always the best teacher. Some day I hope to start posting photos of the project.

Thanks again,

-06
Click to expand...

You say you are looking for a square tipped tool that is .040 wide? I may just be able to help you out. If you think you can make a holder for it, I can give you some dimensions and send you a couple of carbide inserts. They are triangular in shape, have three cutting positions in case you snap on off. When I go out to the garage later, I search through my drawer for one or two to send you if you are interested. I'll see if I can get a pic to you, but for some reason, I have a problem posting from my garage computer, so it may be afternoon before I can get back with you.

I just noticed, that you are not far from me. I'm in Urbana, Ohio which is just a few minutes north of Springfield.
 
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