Can HSS be turned?

strantor said:
I'm getting the feeling that you're sparing me a couple of semesters worth of in-depth technical explanation with this line. So it would be more complicated than heating it to non-ferrous, and then dunking it in ATF? I have an acetylene torch ;)

Well the question is mainly just a theory question, but I actually do want to make some counterbore bits for cap head screws.
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It's pretty easy to make a counter-bore out of O1, and that can be heat treated with a torch. Just turn the pilot and the body to size and mill two or more flutes in it with an end mill and machine a bit of relief on the teeth. Then heat to a dull red, or until it's non-magnetic and quench in motor oil. Once it's hard you can stone the cutting edges to sharpen them.

Here's a link that shows exactly how it's done:

Making Cutting Tools in the Home Shop

Tom
 
When I counterbore, I drill then follow up with an end mill. But then, it isn't hard to do if using a dro.

Patrick
 
I have made counterbores out of drills many times. I clamp a piece of small angle iron on the table of a bench grinder. Then i line the bit up so just the required amount will be ground off, Then i spin the bit into the edge of the grinding wheel. I turn the bit by hand and grind the core until it is the required diameter. Then I grind relief on the edges by pushing harder on the heal than on the lip of the cutting edge. then turn the bit over and grind the other side off. With a little bit of practice you can make a counterbore without much trouble. (The center pilot will not be good enough to cut most likely,so you will have to drill the center hole first,with another bit, to use the counter bore.
 
strantor said:
but at the tip, where (I assume) it's heat treated? I'm thinking to turn either a drill bit or an end mill into a cap head counterbore bit.

Never heard of ceramic inserts. I'll look into it. Thanks.
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The cutting end of a drill/milling bit would be an interrupted cut so ceramic bit would not hold up good next best = grinder:thinking:
There are some good priced counter bore sets on flea bay that are not to bad and you can spend your time using them instead of making them.:))
 
strantor said:
If I wanted to modify a drill bit or an end mill for example, by turning it in the lathe, is this possible? Can it be annealed to make it machinable by carbide tools?
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You'd be better off grinding them.
The toolpost grinder isn't that hard to make from scratch.
Make sure your center lines...line up.

Just make sure you buy good bearings.

You can make lots of tooling from drill bits.

By hand grinding, you'll be able to make specialized cutters in a jiffy.

Don't get them too hot, naturally.
 
Tom, that is a pretty neat link. Looks like he's using propane to harden it. Didn't know that would put out enough heat. I have propane but not oxyacy. However, I do have a small oxy-mapp torch which would heat it hotter than propane unless propane is sufficient.

Dave
 
Dave,

It doesn't matter what you use to heat, as long as it has the capacity to reach critical temps. For a small part like a counter-bore, a propane torch will work fine. The only thing I don't agree with on that link is the temperature he's heating it to. Orange is around 1700ºF and quenching at that temp increases the chance of cracks. O1 only needs to be heated to 1450-1500ºF, a bright red color before quenching in oil. It's also very easy to over temper small parts like that. I never apply heat directly to the tool because the cutting edges that you want hardest, heat up first. I lay the tool on a steel plate and heat the plate instead of the tool. Then it's very easy to control the amount of heat you put in and not go overboard. Quite often, such as for one time use tools, I'll use them full hard and they work great.

Here are a couple of links about heat treating O1 that are quite informative:

Heat Treating Tool Steels

A Woodworkers Guide to Tool Steel and Heat Treating

Tom
 
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thanks, Tom for the useful links. I'll be reading them. Yes, I have always heard heat to "cherry" red,, never orange
 
If you do go the tool post grinder route, be sure to cover all you ways and critical surfaces with damp cloths to catch the grit. Then do a thorough wipe down afterwards just to be sure.
 
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