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I believe this is standard practice in commercial shops
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Broke off carbide drill in hole.
- Thread starter COMachinist
- Start date
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- May 7, 2023
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- 1,914
Battery acid doped with Alum will remove the hardest steel from aluminum, but I doubt it would work on carbide.
Going at a carbide drill with a carbide endmill may have sealed your fate here.
How big is the drill in question and how deep down in the hole?
How much of the drill is stuck?
What I was wondering...
Never used carbide drill bits, but might a carbide center drill (if the hole is large enough) work to get a new hole started in the end of the bit, then try to drill out the larger bit with one a size smaller? Just spitballin' here...
- Joined
- Sep 10, 2013
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2.5mm I was trying drill out a 3mm broken off screw in the hole. That dang screw was harder than all git out too. That didn't help any. It is supposed to be 3mm-.5 x12 metric screw. I punched the screw as close to center as could. Thes tarted drilling with s carbide left twist an it went about I guess 5m in then it snaped it broke off. Down in the bottom. I know I should have left alone until I could get help but you know, just had to try.
CH
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- Sep 10, 2013
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Looked in the phone book but the the nearest edm shop is in Denver about 75 miles of the worst traffic in the world. Maybe 2hr each way maybe longer. We are now little Comnuirodo! So many Comufoniaist out here now.
CH
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You have left out some vital info. [if I missed it in scanning the entire thread twice, I apologize]
How much of the drill is in the workpiece? 1/2" long? 2" long?
What is the diameter of the drill?
... for the win -- how deep is the top of the carbide drill part?
******
Do you have the option of using an annular cutter to remove stock around the drill (ID must be close to the OD of the broken carbide drill)?
-- There isn't a one-size fits-all solution unless you have a portable sinker EDM, which was mentioned above.
Is this part so valuable you cannot scrap it?
There many more.
How much of the drill is in the workpiece? 1/2" long? 2" long?
What is the diameter of the drill?
... for the win -- how deep is the top of the carbide drill part?
******
Do you have the option of using an annular cutter to remove stock around the drill (ID must be close to the OD of the broken carbide drill)?
-- There isn't a one-size fits-all solution unless you have a portable sinker EDM, which was mentioned above.
Is this part so valuable you cannot scrap it?
There many more.
I know the traffic there well. It really is your only good option.
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- Oct 13, 2014
- Messages
- 8,717
Is the broken screw flush with the surface? you might be able to braze a bit of key stock to the end and turn the screw out. Otherwise the EDM sounds like your best bet.
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- Feb 1, 2015
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- 9,822
If the original screw was 12mm, the carbide drill remnant can't be very long or deep in the hole. I would try a hardened pick to break the drill. I had this happen when installing a cover for a DRO on the back of my lathe. I was able to break enough of the drill to use a shortened screw.
There are diamond bits for a Dremel that will cut the carbide although you may go through a few in the process. There were a number of threads on this site regarding home built sinker EDM machines.
The approach depends a lot on whether the item is small enough to work on a mill or drill press, if it is cosmetic, how soon does the item need to be back in service, etc. Personally, I would try the pick approach first. An old chainsaw file can be ground into a tiny punch and used to break the carbide. Try to hit the drill flute rather than dead on. If you resort to the diamond burrs, go slowly to allow the diamonds to do their work. It is easy to strip them off the burr, rendering it useless. As a last resort, I would consider the home built EDM.
There are diamond bits for a Dremel that will cut the carbide although you may go through a few in the process. There were a number of threads on this site regarding home built sinker EDM machines.
The approach depends a lot on whether the item is small enough to work on a mill or drill press, if it is cosmetic, how soon does the item need to be back in service, etc. Personally, I would try the pick approach first. An old chainsaw file can be ground into a tiny punch and used to break the carbide. Try to hit the drill flute rather than dead on. If you resort to the diamond burrs, go slowly to allow the diamonds to do their work. It is easy to strip them off the burr, rendering it useless. As a last resort, I would consider the home built EDM.
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- Sep 10, 2013
- Messages
- 572
See post #14