[zcases]

I remember a post somewhere on the zone, but cannot seem to find it. Someone mentioned some "stuff" that would eat away taps and not hurt the surrounding base metal.

A co-worker has a broken off stud, corroded into an aluminum block, in a boat where access is difficult. Any ideas? I am interested to hear.......

Thanks
Scott

[lakeside]

can you center drill and get a drill just under root size of thread in this location if so drill to depth and the materail left will be a fine wire and you could pull out with pick and niddlenose

[Adobe Machine]

There is no "Easy Button " on that one:Get the broken bolt leval at the top so you can find center and punch. May have to use a small stone in a Dremil type tool.Use a left handed drill just under root size and start drilling.About 85% of the time the broken bolt will turn out with the left handed drill. Center accuracy and angle of the drill are the key to success,a little off center or drilling crooked gets you right into the alum.and a bigger mess.Where we could not use a mill to drill or extract, I always had a "spotter" to watch and help the one drilling keep the drilling angle correct.Most likley you will have to HeliCoil or similar as the threads in an Alum. block or head will be rotten ( Alum +water+steel= mess)and so that this will not happen again use "Anti Seize", the Marine Mechanics friend.(and machinery and machine tools )

Adobe (old as dirt )

[lakeside]

.Most likley you will have to HeliCoil or similar as the threads in an Alum. block or head will be rotten ( Alum +water+steel= mess)....

They do have stainless steel HeliCoil

[Mcgyver]

I remember a post somewhere on the zone, but cannot seem to find it. Someone mentioned some "stuff" that would eat away taps and not hurt the surrounding base metal.

Alum, Aluminum Sulfate. never done it but the hard part seems to be finding the stuff, used for tanning etc. create a saturated solution, warm, immerse part and wait - will dissolve a tap out of AL without hurting AL. don't think its going to work in situ though. Me being paranoid, I'd check out the health aspects first, but its been done by many a home shop type

[lakeside]

you could also drill stud center out 75% in depth and left hand tap a screw that may back out old stud when it bottoms out or can you weld a new stud on end of broken one?

[rhino]

Broken tap: drill out using a carbide drill. (or ultra slow speed using a cobalt drill).
if this dosen't work try heating the tap slowly with oxy to soften it (wait till it cools down) then drill out (slow speed again) using HSS drill. (both work for me)

Broken stud: if using ezi-outs (screw extractors) doesn't work drill out to just under minor diameter of stud thread aand twist out with pliers.

[roseblade]

i know this thread is old, but the problem is always with us. i have just this minute succesfully removed taps broken off in a pair of gold bracelets . the produst you seek is ´vissin´screw extractor made by ´burgeon ´and available from jh walsh and son of hatton garden london .i guess it is sold for the watch/clock repair trade..i found this zone because i am curious to know what it is composed of..............i dont know how useful it would prove as a general solution to the problem ,....it does not seem to be highly acidic , bears no toxicity warning and smells not at all ..........but boy it eats taps if one can immerse the area and heat .good luck

[roseblade]

vissin made by burgeon sold by jh walsh of hatton garden london......clock repairers friend!!.....just succesfully dissolved four broken taps, found this forum investigating its likely formulation good luck

[rhundl]

If you keep breaking them you will get better at removing them...haha All joking aside, they do make tap extractors and you can find them at rex supply. They rarley work though. The best way i have found is to drill them out with a carbide mill, but this is very difficult and needs to be done on a milling machine. The stud is alot easier, start by grinding a flat area on the face of the bolt, then centerpunch the bolt in the center, drill a small hole like .125 or so. Heat the bolt primarily until it turns orange or red, drop cold water on the bolt, just a few drops. Then spray with a penatrating oil, we use something called " s'ok " It is the best stuff I have used. Put your EZ Out in and try removing the bolt. One of the biggest mistakes made when using EZ Outs is drilling the hole way off center and drilling way to large of a hole. These are great tools if used properly, Broken ez outs are as hard to get out as taps so be aggressive but gentle. Hope this helps

[307startup]

I hate the "heat it up" method...especially when you're dealing with aluminum. You take the heat treat out of the material, then the threads WILL strip for sure because the aluminum is so damn soft. Will it damage the whole block or head or intake or whatever? No, it'll damage the area that was heated. Removing a tap that is stuck is easier if you didn't damage threads when it was going in...you can use a couple of drill rods with a diameter smaller than the flutes in the tap, with a larger drill rod to act as a center "spacer"...use a hose clamp to tie them together and use a wrench to run it out. Run the drill rods down the flutes as far as you can reach and you have a fairly no-pain method of removal. Trust me, I know, as the morons at work break taps at least once a week, sometimes once a day. I don't have an EDM or expensive drills. Ezy-outs NEVER work for me, maybe I'm just stupid.

[roseblade]

hi guys..many thanx for ideas, but the minute scale of my work precludes any of your suggestions....vissin screw extractor gobbles small screws and taps like a dream, and i can imagine that if one made a cottle around the area to be treated out of say plasticene, or even hot glue to retain the fluid and gently heat the piece until the solution boils, one could eat out an engine block size tap.......if it looks like eating the block , then mask off with copydex...... i started out trying to dissolve broken off drills and taps with all manner of acids , nitric included(not phosphoric) at all diutions , mixes and temperatures( remember i´m working gold) and NOTHING comes close to vissin, honest injun. as i say , iwas lookin into possible formulations when i stumbled on this site, and couldnt resist posting DESPITE the extreme difficulty of doing so ..this is one cumbersome beast... it has taken MUCH longer to join up and post than to cook out a tap , yours in peace , paul

[mcostello1]

Heating the part in Alum will disolve aluminum, will also dissolve all other steel parts you might not want dissolved so be careful. Takes a while but works.