Where can I buy decent HSS blanks from Canada?

martik777 said:
No, I'm not threading, just turning off the existing threads for length of 1/4-1/2" and need a good remaining 1/2-13 thread. If I use the DCMT or brazed carbide it galls the thread so I cannot easily thread on a nut after cutting the chamfer.

Set screw is 2" long. Running 4-500rpm. They are fairly hard but I can file them. Chips are little dark bluish curls about 1/8th inch long. Need to do 100's.

I prefer to do the cut and 45 degree chamfer with the one tool.
Right now I do one pass to get 90% of the material off, then 2 spring passes to dimension

Thanks, I'll checkout that HSS at KBC. I'm also looking at these: https://www.aliexpress.com/item/4001294281524.html?spm=a2g0o.9042311.0.0.2bc44c4dMNwtv9


See photoView attachment 396413
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that's set up as a left hand turning tool. You want a right hand tool. What's happening is you are not getting close enough, and its acting like a forming tool, you have a lot of metal engagement. You want less.

if that were the short side on the left and the long on the right it would be better. But really I would want something almost straight on the left, and slightly relieved on the right. I have a cutter like that and use it for things like this. It has no problem cutting socket head and set screws.
 
Kevin T said:
It's hard to see the profile on your cutter but assuming it is close enough have you tried to rotate the tool post a bit so it's more pointy where it meets the part? I've done some of this work before and it seems like the hard stuff sometimes needs a point to work through the hardened exterior. So then what happens is you need to tweak your feeds to get the finish you are after. I am always learning but looking at your picture, even if the parts are hard as hell, you should be able to do 10-15 of them (at least) before you need to touch up your HSS cutter with a stone. Do you have some good stones you can quickly sharpen your cutter with? They are not all created equal. Are you using any cutting fluid? That should get you a few more between stone work too.

EDIT: Maybe a couple shots of your cutter from different angles would help.
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Twisting it so the pointy end is perpendicular doesn't help much. It's really tough on the 5/8" set screws, probably 5:1 as hard to machine as the 1/2" screws. Even a right-hand carbide tool just galls the threads so I have to finish with a sharp HSS. I reground and took another photo. Stoning doesn't take off enough so I just regrind with a fine wheel. Fluid doesn't seem to make it last longer either.
If I didn't have the Momax I couldn't do this, the Chinese HSS is like chalk!

setscrew2.jpg
 
woodchucker said:
that's set up as a left hand turning tool. You want a right hand tool. What's happening is you are not getting close enough, and its acting like a forming tool, you have a lot of metal engagement. You want less.

if that were the short side on the left and the long on the right it would be better. But really I would want something almost straight on the left, and slightly relieved on the right. I have a cutter like that and use it for things like this. It has no problem cutting socket head and set screws.
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I'll try that on the next resharpening. Did you cut 5/8" screws down .100"? Those are murderous!
 
Just spitballing but the chips look ok so you must be close to ideal for speed and feed. It could be an optical illusion but the cutter looks like nuetral to negative rake, which would be good for carbide, maybe not ideal for HSS?

Are there any tempering tricks you can employ? I have read about people heating up metals to make them more machinable but not sure if changing the hardness is going to work for your purpose..or if it's possible.

I'm saving that metallurgy stuff for my old age! lol
 
You might try dropping your sfm to about 40 ft/min That would be 311 rpm. If you switch to carbide use a brazed tool. Most brazed carbides I have seen recently require a finish grind to get the correct clearance angles
 
Illinoyance said:
You might try dropping your sfm to about 40 ft/min That would be 311 rpm. If you switch to carbide use a brazed tool. Most brazed carbides I have seen recently require a finish grind to get the correct clearance angles
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I'll try slower RPM next batch. I tried a sharpened angled brazed carbide but it left too much of a burr to allow me to thread on a nut. I still had to finish with a sharp HSS to be able to get the nut on
 
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