PDA

View Full Version : how to extract a broke carbide drill bit?



polygons
02-09-2004, 12:30 AM
This sucker is a #43 carbide bit for a 4-40 tap and it broke off flush. Any ideas how I can get it out? Diamond bit maybe?

Thrud
02-09-2004, 12:39 AM
Diamond is the only thing that will cut it. Run it in Left hand direction it might free the bit faster that way, use water for lubricant.

Paul Alciatore
02-09-2004, 03:23 PM
Wouldn't one of those EDM devices I have been reading about do it?


Paul A.

wierdscience
02-10-2004, 12:20 AM
I did one #53 I think it was,I took a lead pencil and coated the area around the hole with lead,then I took a small brass washer that just fit the top of the bit and laid it flat ontop of the broken bit,silver soldered it in and then gripped it with a sharp pair of visegrip pliers backing it out left hand.The pencil lead keeps the solder from sticking to the work piece.

crypto
02-10-2004, 12:45 AM
What kind of material is it imbedded in. Some time ago I purchased one of those sets of 1/8" shank diamond burrs sold by Harbor Freight. Kept it around for emergencies and I had one. Sure enough I was able to use-destroy might be a better word-several of those little burrs but I was able to break things up enough to loosen the drill.

I like the silver solder and the left hand approach. I didn't think of it at the time.

polygons
02-10-2004, 10:25 AM
the bit is stuck in silver. it's flush so the solder a handle idea while great probably wont work. I ordered some diamond bits to see if that will work.

JCHannum
02-10-2004, 10:37 AM
A question. Why would you use carbide to drill silver? That is asking for trouble.

polygons
02-10-2004, 10:41 AM
I was tapping a hole and didnt have a HSS bit, only the carbide one that came with the tap.
I had no idea it would bind up so quick. I was going nice and easy with it and when I was 1/2" in , snap!!!
This is my first time working with silver. Is HSS the best to work with for silver?

Forrest Addy
02-10-2004, 10:58 AM
Carbide and silver have different expansion rates. Silver isquite high, carbidemuch lower. Heat up the mess to 500 degrees and see if you can get the carbide drill out.

Silver chips love to pack and self-weld. You need to clear the drill frequently and use a cutting fluid.

Evan
02-10-2004, 11:58 AM
I'm afraid you may have to scrap the part. Silver is almost as bad as copper for work hardening. That bit is well and truly stuck. A 1/2" hole is pretty deep for such a small bit. About the only thing I can think of is, if possible, finish the hole from the other side with another bit and try to drive it back out with a fine punch, at least enough to get a grip on it.

Artpro
02-10-2004, 06:52 PM
Hi. I'd try using a tap extractor if the flutes are clear enough to get it in there alongside the tap.

Evan
02-10-2004, 06:56 PM
My understanding is this is a broken drill bit, a carbide tap drill. Very small, .089"

[This message has been edited by Evan (edited 02-10-2004).]

lynnl
02-10-2004, 08:32 PM
In the past people have stated that alum can be used to disolve steel taps/drills in aluminum and other non-ferrous mat'ls. Anyone know the reaction of silver and carbide in the presence of alum?

Evan
02-10-2004, 11:44 PM
It might eat the silver but the silicon carbide will still be there when the sun burns out. The only way to even etch SiC with acid is Hydroflouric acid, BAD STUFF, and very slow. Won't work I'm afraid.

J. R. Williams
02-11-2004, 12:01 AM
I managed to break off a tap flush in an aluminum part and as it was a spiral flute, there was no way to back it out so I made a simple hollow end mill with the hole the diameter of the tap and the OD the diameter of a tap drill. The mill was slowly fed into the work to the depth of the tap section. Then a small punch was used to break off the small amount of material holding the tap. The hole was tapped to the larger size and a short section of new material was threaded into the hole and then drilled and tapped to the former size. The part was saved..

JRW

Thrud
02-11-2004, 03:04 AM
You were drilling this by hand, I take it?

If so slap yourself upside the head a good one. Never, EVER drill small holes with carbide drills unless the work is completely restrained and unable to move. Because if it moves evena tiny bit the carbide will shatter like glass. This means the work is in a vise and the bit is in a drill press or mill - not a hand drill!

Carbide is for drilling tough materials not silver. Silver can be drilled with a wood bit.

polygons
02-11-2004, 10:42 AM
Yep it was clamped down in a cross slide, and the bit was only fed a little at a time allowing it to expell the shavngs. The problem it I was drilling in a silver casting and im sure I hit an air bubble or somthing.
What is the best bit to use for soft metals like silver or brass?

Rustybolt
02-11-2004, 11:08 AM
Use a regular HSS bit and stone the lip to 0 rake. Stoning the lip keeps the bit from grabbing and drilling itself deeper. You could even use a carbon steel bit for that matter.

Evan
02-11-2004, 11:48 AM
Treat it like copper, you might even consider using milk for lube. Silver work hardens quickly and hard. Depending on the alloy it will have up to 20% copper in it (unless it is fine silver).

win worm
02-11-2004, 04:11 PM
Hello I had a problem like that several times and I solved it by taking a high speed
die grinder and using a small carbide rotary deburring tip the one that has cutting flutes on the tip with light pressure you can heat up the drill or tap. Take a small punch it will break apart a little at a time with care it will do the job. Good Luck

Evan
02-11-2004, 04:14 PM
Using carbide against carbide probably isn't going to get too far.

win worm
02-11-2004, 04:37 PM
<font face="Verdana, Arial" size="2">Originally posted by win worm:
Hello I had a problem like that several times and I solved it by taking a high speed
die grinder and using a small carbide rotary deburring tip the one that has cutting flutes on the tip with light pressure you can heat up the drill or tap. Take a small punch it will break apart a little at a time with care it will do the job. Good Luck</font> the idea is heat it up so will get brittle not to cut it

Evan
02-11-2004, 04:48 PM
Heating carbide doesn't make it any more brittle. That's the entire point of using carbide, it can take very high heat.

gunsmith
02-11-2004, 07:24 PM
I had a similar problem with a broke carbide in a hole. I solved the problem by using a friends punch press. I punched out the piece that contained the carbide. Then I punched out a second piece as a blank and soldered it into place and started again. Might work for you as well. Good luck

jkoper
02-12-2004, 02:49 AM
EDM or tap disintgrator is your best option. If the carbide was in steel sometimes you can shatter it,but I don't believe it would work in silver its much to soft.If the piece is worth the money look for a small job shop that could burn is out for you.