Drilling tool steel

george tichbourne

george tichbourne

Joined
Apr 19, 1999
Messages
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More specifically, can a hardened four flute tool steel end mill be drilled by a carbide drill bit? What precautions must be taken?

Alternative method is locating an EDM shop to burn a hole in the end mill, don't have any friends around here with an EDM.
 
Most of the carbides I use are capable of drilling anything up to 82 on the Rockwell scale. The carbides are brittle so it is key to let the bit do the work without pushing it in too fast or you will shatter the tip. Exit out the other side can be sometimes frustrating as the tips will ofen break or partially break at that point. I would just drill numerous holes all the way as far down to the point of just about to break through the other side and stop before exiting if I only had one drill. At least that way most of the major drilling is done and all you have to focus on is the final exit on them which can be done even with a broken bit.

Crank up the drill press to a higher speed and they work better.

STR
 
Carbide endmills and drills are capable of cutting out a broken hss endmill. The advice given to go slow with the feed and let it do the work is a good one.

Make sure that the workpiece is rigid. Don't hold it in your hand here, either clamp it to the table or in a vice and then clamp the vise to the table. If it moves, you could have a broken carbide drill in there instead.(Been there, done that, took it to work and burned it out... I work in sinker edm... )

Don't use any coolant. Let it run dry. It works better when hardmilling to have a little heat. In general, don't use coolant with carbide unless you can flood it.

Jamie
 
Thanks Jamie, I have been talking to most of my tool and die friends and that seems to be the consensus though some said they have never worked on anything over RC50 and had no idea.
 
What're you making, George? Sounds interesting... making a piloted endmill or something? Maybe if Don Robinson sees this he will chime in.
 
Yes it is a piloted end mill but reground to 7/16" diameter with a 1/8" pilot for folders. I am trying to improve on my folder's action and rigidity.
 
george tichbourne said:
Yes it is a piloted end mill but reground to 7/16" diameter with a 1/8" pilot for folders. I am trying to improve on my folder's action and rigidity.
Click to expand...

Keep us posted, George! I'll be very interested in seeing how you mak eout with that. :thumbup:
 
That is going to save a lot of work, thanks.

Where I run into trouble is not knowing exactly what the unit that I want is called and what industry it is used in.
 
george tichbourne said:
That is going to save a lot of work, thanks.

Where I run into trouble is not knowing exactly what the unit that I want is called and what industry it is used in.
Click to expand...

From being in the industry so long now, I can usually help with that, George. Drop me a line of post it here for others to see. I am always eager to help. ;)
 
GOT ONE!

After many discussions with my tool supplier who repeatedly told me that the size that I wanted was unavailable I ordered one with an oversize pilot intending to turn the pilot size down a tiny bit to fit.

Friday the exact size that I wanted arrived 7/16 with 1/8 pilot from Cleveland Tools. I found that odd because a buddy is an inside salesman at Cleveland and when I described what I wanted to him he said it wasn't available as well.

I guess every once in a while you have to get lucky.
 
OSG will also custom-make anything you ask for. I've used them for a lot of different things.
 
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