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Posted: 6/18/2007 8:52:57 AM EDT
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Oh no! I was drilling the front take down detent pin hole and the 3/32" drill bit snapped! The broken piece is about 3/8" long and is jammed in about 3/32" from the top. Can somebody please offer some advice on how I can resolve this? Thanks in advance for your help. FireMagus |
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A left-handed drill bit could bite in enough to spin out the broken bit. You are in a very difficult spot of trouble, as the aluminum receiver is considerably more prone to damage than a hardened piece of drill bit. Is the broken bit flush with the receiver, protruding, or down in the hole you were drilling? First off, you need to immobilize the receiver. Take your time to do this properly. There are screw extractors on the market. There are several types of these- some resemble corkscrews, some are straight tapered shanks, and some are combination drill/screw extractors. The problem is they are meant to remove bolts and screws that have snapped off- not drill bits that are hardened. You may require a tungsten bit in the end. The first thing I would try is a left-handed drill bit. You may want to make the first tentative turns by hand- to see if you can get the bit to bite in. Go slow and be methodical. Don't get frustrated. Your "pilot" hole isn't very deep, so go slow and make sure the bit isn't wandering. |
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I managed to use a tap extractor to remove a broken drill bit near that size once. Though I did go through a bunch of the steel fingers until I managed to budge it. Search for tap extractor here if you've not seen one before. Edit for retarded typing. |
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Is there any part of the bit sticking out to where you can grab ahold of it with pliers? If so take a pair of vise grips, get ahold of the bit as close to the bottom as possible and as tight as possible, and slowly back the bit out. Try to keep the distance between the receiver and grips as close as you can w/o touching the receiver it self... Never done it before, so not working of first hand knowledge, just seems do-able! |
| I would probably burn it out, drill bit vs aluminum.. you have about 0% chance of getting it out mechanically without buggering your aluminum. If you have a small tip, a bucket of water, a rag, and a steady hand you can burn it out without damage. There will be slag in the hole but you can deal with that later. use the rag to keep the receiver cool while you heat the broken bit. Use that shooters hand of yours and keep the heat on the bit. When it starts to melt hit the gas and watch it disappear. |
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Thanks for the input, guys. Wouldn't you know it that this would happen at the final stages of things! All the sanding and filling was finished and all the holes drilled and tapped. All I had left to do was drill the roll pin bolt release hole and this one. I have no experience with JB Weld, but I'm thinking that maybe I could use it as glue and place a small dab onto the bit top and JB Weld a smaller bit to it. Would this be strong enough for me to pull the broken bit out? FireMagus |
| A woodworkers solution. Bore it out with a larger end mill in your drill, turn an aluminum dowel to fit in the larger bore hole, cross drill and pin the dowel in with a roll pin, drill the dowel for your detent spring....don't tell anyone and they'll never know. |
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There's some very good suggestions here. Thanks a lot. There is a chemical with the generic name "alum" (Aluminum Sulfate) that is known to disolve steel, but not aluminum (source: rec.crafts.metalwork). I'm going to give it a shot since it's cheap and readily available at most garden centers. I'm tempted to try some of the other suggestions first just to see what works best. I'll let everyone know how it turns out. Thanks again. FireMagus |
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I'm wondering if there is a way to shrink the bit using Gumfreeze(tm) or some other refrigerant. I'd try zapping the local area with a couple shots of Gumfreeze, then warming up the aluminum. The steel bit should absorb heat more slowly, causing the aluminum to release the bit. It may take more than one application of cool/heat to get the job done, but it would assist in turning the bit out, I'd think. Just an idea. |
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If you plan to drill more holes in aluminum, or try to remove that broken bit, use Tap Magic cutting fluid. www.tapmagic.com/ |
You'd be better off heating the whole thing. Aluminum has a higher coefficient of expansion than steel, and the receiver will open up a little relative to the drill bit. However, the bit is so small the difference will be pretty tiny. |
I just found this posted wrongly. Figured I would bring it over here.
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My bad on the posting. If you go to a larger shop they probably have an edm for burning out bits. Talk to the front office. They wont know how much to charge 20 bucks out to do it. But try my first 2 suggestions. It is what I do before going the EDM route. |
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CARBIDE drill bits only. Left handed drill bit ( pretty small so good luck) Im thinking its too small to get a good bite to back that out.  I use the shit out of these and have never had one go bad if I did my part. www.roadstarmagazine.com/modules.php?name=News&file=article&sid=233www.carbidedepot.com/formulas-tap-helicoil.htm Most machine shops will put one in but once again the size could be a problme |
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