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Broken screw, drill bit and tap removal tips, the do and the don't!!

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PRiggs78

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We've all pretty much heard of the alum bath trick to remove drills, taps, and screws of ferrous makeup when broken off in aluminum.

Not an engine part, but decided to share as an FYI.

A lower trigger housing for a firearm I designed and made.

While adding some detent holes for quick take down pins in the already anodized part, a 5/64 drill snapped off! Noooooo!!!

Well, Alum saved the day after 7 hours soak. Also, the alum bath seemingly totally removed the anodizing!!!

Not sure if it is the dye that was removed, or both dye and oxide layer.

The part had a type III mil spec hard coat.

So, use the alum method on raw, unfinished aluminum!!!
 

Wizard69

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I've run into the broken drills in aluminum at work and ended up scrapping the parts. Its extremely frustrating but also very easy to do when drilling with very small drills. Largely though I blame myself for being in a hurry. Learning to manually peck drill carefully is one way to avoid such breakage and frankly that rubs my personality the wrong way.
 

chrsbrbnk

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wow that's a bummer, should make drilling easier though hard coat is always tough on the tooling going thru
 

SmithDoor

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If can not get broken part out go to Automotive Machine shop and they have a EDM machine and about 10 later it will out ever time.
It can take longer only to justify there bill.

On larger sizes ½" and up holes I use MIG welder and save cost of the EDM machine.

Dave

We've all pretty much heard of the alum bath trick to remove drills, taps, and screws of ferrous makeup when broken off in aluminum.

Not an engine part, but decided to share as an FYI.

A lower trigger housing for a firearm I designed and made.

While adding some detent holes for quick take down pins in the already anodized part, a 5/64 drill snapped off! Noooooo!!!

Well, Alum saved the day after 7 hours soak. Also, the alum bath seemingly totally removed the anodizing!!!

Not sure if it is the dye that was removed, or both dye and oxide layer.

The part had a type III mil spec hard coat.

So, use the alum method on raw, unfinished aluminum!!!
 

petertha

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Alum did not work well for me. Well... it made a mess of the original part long before the M3 tap was anywhere near dissolved. Mind you it was a coated tap as opposed to uncoated HSS & may have had something to do with it. Anyways if presented this issue again I think I would make an annular cutter to remove a sidewall core, plug the hole with a slug of native aluminum with permanent Loctite & drill/tap again. Or possibly find a carbide that could drill out the broken tap but I didnt have much luck with that either using both ball & flat bottom EM.

SmithDoor I'm interested in ballpark cost for EDM burnout if you care to mention
 

SmithDoor

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I work as machinist at place did that work. It took about 10 to 15 minutes to setup and finish a hole.
The place would charger at least $30 and up for each hole.
I think they look at part and just price. If a old farm equipment it low if was a very new costly equipment then price would go up.

Dave

Alum did not work well for me. Well... it made a mess of the original part long before the M3 tap was anywhere near dissolved. Mind you it was a coated tap as opposed to uncoated HSS & may have had something to do with it. Anyways if presented this issue again I think I would make an annular cutter to remove a sidewall core, plug the hole with a slug of native aluminum with permanent Loctite & drill/tap again. Or possibly find a carbide that could drill out the broken tap but I didnt have much luck with that either using both ball & flat bottom EM.

SmithDoor I'm interested in ballpark cost for EDM burnout if you care to mention
 

kwoodhands

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Alum did not work well for me. Well... it made a mess of the original part long before the M3 tap was anywhere near dissolved. Mind you it was a coated tap as opposed to uncoated HSS & may have had something to do with it. Anyways if presented this issue again I think I would make an annular cutter to remove a sidewall core, plug the hole with a slug of native aluminum with permanent Loctite & drill/tap again. Or possibly find a carbide that could drill out the broken tap but I didn'
t have much luck with that either using both ball & flat bottom EM.

SmithDoor I'm interested in ballpark cost for EDM burnout if you care to mention
I broke a 2/56 tap in an aluminum cylinder . Core drilling was not an option as I would have to drill 1-3/4" to get to the other side of the cylinder. I tried alum, has worked in the past but not this time. Before scrapping the part I ground the stub of the tap flush with the cylinder head. I used a Dremel tool with a ball end diamond point.
After the tap was flush with the cylinder head I installed the part on the mills vice. I used the same ball end diamond point to bore 3/8" deep. I brushed Moly Dee tap lubricant on the ball point and a half hour later I got to 3/8" I then re-drilled for 3/48 and tapped the hole. Then re-drilled the other 7 holes and tapped them 3/48.
mike
 

grahamgollar

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I've found that the best solution to preventing small drill breakage in Al is i) plenty of lub, e.g. paraffin [or kerosine to you guys] and ii) regular withdrawal of the drill to clear the flukes - don't try and go the full depth in one take. The latter is not easy in an NC mode so it's back to basics!
 

bruski

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I have removed broken taps from aluminum with nitric acid. The acid doesn't attack the aluminum, just the hardened tap. First clean off any cutting oils with carb cleaner then build a dam around the hole with the broken tap in it from modeling clay. Put a few drops of the nitric acid in the hole and wait until bubbling stops and repeat a few times until tap falls out. Some times a little bit of heat will speed up the process.

bruski
 

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