Drill shank hardness

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spro
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Re: Drill shank hardness

Post by spro » Mon May 20, 2019 2:51 pm

Why did you say that? Please explain.

spro
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Re: Drill shank hardness

Post by spro » Mon May 20, 2019 3:01 pm

Okay. You don't have to explain. It already happened and it worked. Roll pins are deceptive in how they are machined. Mr. Warm is familiar with the ones he delt with in Industry. His advise is golden and I/ we can see that the tip is beveled to not flare out in the hole. It also captures the standard types split pin at its taper. It is a hollow punch drilled a certain way and yes, Use it or lose it.
Last edited by spro on Mon May 20, 2019 3:16 pm, edited 1 time in total.

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SteveM
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Re: Drill shank hardness

Post by SteveM » Mon May 20, 2019 3:16 pm

I have a pile of broken carbide end mills that came in a lot I picked up at an auction.

I'm going to go thru and pull some out to keep for making tools. There's a number of smaller diameter ones that I could make a bit that will go into a holder, like a boring bar.

Steve

spro
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Re: Drill shank hardness

Post by spro » Mon May 20, 2019 3:20 pm

So true, Steve M. There are so many angles which a person could use instead of grinding them.
Last edited by spro on Mon May 20, 2019 3:26 pm, edited 1 time in total.

Harold_V
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Re: Drill shank hardness

Post by Harold_V » Mon May 20, 2019 3:21 pm

Quenching HSS in water would likely be a mistake. It suffers from micro-fracturing, or may even shatter (like glass). Once heated at the appropriate rate, and held at temperature for the appropriate time (determined by the alloy in question), the item would then be quenched, either in oil, or in still air. Again, that would be determined by the alloy in question, as well as its mass. Large pieces would normally be oil quenched, while small pieces may be successfully quenched by air.

Previously heat treated items that are reheated should be allowed to air cool. HSS is difficult to anneal, and must be cooled at a slow pace, usually no more than 50°/hour, assuming it was heated to the required critical temperature. That procedure is generally accomplished by furnace cooling.

H
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tornitore45
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Re: Drill shank hardness

Post by tornitore45 » Mon May 20, 2019 4:39 pm

Opps! You're right. Probably only works with HF drills.
If one is lucky, otherwise there is not enough Carbon in recycled soup can to harden.
Bashing HF is a popular sport but actually their tool quality has improved, still cutting tools are iffy.
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spro
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Re: Drill shank hardness

Post by spro » Mon May 20, 2019 5:12 pm

If we look at pic #2 about these roll pin tools.. We can see steel hex shanks with a cover over them. This is exactly how one would hold a punch. It also allowed him to grip it and drill the mating diameter of the drill shank. If it worked well enough for him it is a good tip. Sometimes off shore too brittle or mostly iron but there are uses for them beyond intended purpose.

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liveaboard
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Re: Drill shank hardness

Post by liveaboard » Tue May 21, 2019 4:26 am

So, can anyone tell me how to
A; heat treat an HSS drill shank
B; heat treat a cobalt drill shank

Even if the process is not possible at home, it would be nice to know how it's done.
I have a computer controlled ceramic kiln that can reach 1050C, 1922F

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tornitore45
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Re: Drill shank hardness

Post by tornitore45 » Tue May 21, 2019 4:59 am

Google HSS heat treatment hardening

This is the first link that comes up
They quote temperatures in excess of 1200 C

https://www.totalmateria.com/page.aspx? ... N=CN&NM=57
Mauro Gaetano
in Austin TX

pete
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Re: Drill shank hardness

Post by pete » Tue May 21, 2019 8:29 am

There's very good reasons why the HSS straight drill shanks aren't hardened. Grip is the main one, under the drill chucks tightening pressures the drill shank slightly deforms and allows much more surface contact area plus you then have a slightly 3 lobed shape. Obviously the effect is minor and well within the metals elasticity point but still under it's yield limit so you don't get permanent deformation and marking of the drill shank. There's a whole lot more to producing high quality drills than just the heat treatment and sharpening. With solid carbide drills that deformation isn't going to happen so diamond plated chuck jaws are then needed to get enough grip on the shank. Albrecht and a few others make them. It's cheaper to just use a collet if you've got one that will fit the shank.

If a drill spins and chews up the shank then the chucks at fault. I can't afford to have a cheap chuck doing that to what I think were fairly expensive drills that I've bought. I've yet to have a drill spin in any decent quality chuck I've bought. My best guess is the drill would snap somewhere on the flutes before they'd spin.

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liveaboard
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Re: Drill shank hardness

Post by liveaboard » Tue May 21, 2019 11:52 am

I want to harden shanks of used drills to use as cutting tools. I find the sizes handy, and there seem to be plenty of material in my junk drawer.

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Re: Drill shank hardness

Post by Harold_V » Wed May 22, 2019 1:28 am

Do keep in mind, the hardened portion of twist drills generally extends a little beyond the flutes, so you can still use them in their original condition so long as you can fashion a suitable cutting edge within the designated area.

If you're at all curious about where heat treat ends, grip a (damaged) drill by the fluted end, and take a light pass (a few thou) on the shank. The transition from soft to hard occurs relatively quickly, and the difference will be obvious.

It's absolutely amazing, the degree of control offered by induction heating.

H
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