Removing Broken Tap

You think dentists are expensive drilling small holes, take your bit of stainless to a professional engineer to get the broken tap removed, you might then think the dentist is a bit cheap. I think the thing is, the engineer doesn't want the job, and is hoping you'll go away and annoy someone else.

Ian S C

Glad the problem is solved.

After vainly trying most of the methods mentioned above, I successfully removed a broken tap using a Walton brand tap extractor - one tool I hope never to have to use again!

These extractors are equipped with fingers which are inserted into the flutes thus allowing the tap to be turned. Unlike many tools they come with comprehensive instructions and the promise of free replacement of damaged parts (other than the fingers).

Thanks S.O.D, I suspect that is the problem. My 'alum' came from internet and the origin is stated India. I can well imagine it is the ammonium sulphate version.

I am having difficulty sourcing a trial size pack of potassium sulphate - local pharmacists just ask 'what is that'!

Noted also your advice as being PAS / Potash!

John.

Earlier this week I broke a No. 50 drill in a block of Aluminum . Some time ago I bought a product called BTR-10-broken tap remover, (Translunar technology Ltd , Bucks) it contains 33% aluminum sulphate.

The instructions say to dissolve a quantity in water in a aluminum /glass container and simmer the part . It states no action occurs at a lower temp.

After approx 1 hour enough of the drill had been dissolved and it just fell out.

If you are close to Stoke On Trent you are welcome to borrow the solution.

Edited By ian j on 28/06/2019 14:00:24

Long ago I had a related problem, with a crankcase through-bolt seized firmly in the casing. It was removed using Nitric Acid, a process which dissolves the steel but does not attack the aluminium. It also produces lots of brown fumes and annoys next door's cat, so needs to be done at the bottom of the garden and not too near to other means of transport. I expect it is ruled out nowadays. The remains of the steel through bolt came out with nicely pointed ends, where the acid had attacked for longest.

Cheers, Tim

I broke a 1/4 bsf tap about three diameters deep in mild steel. The drill had been undersize so I only had myself to blame. The workpiece was in the mill vice, so I left it where it was and used a solid carbide drill of about the core diameter using the fine feed very slowly. The carbide cut through the hss beautifully and I could just tip the remaining bits out. I re drilled with the correct size and found a replacement tap.

I would not want that to happen very often.

Thanks Ian J, appreciated but I am in Dorset so a kind offer that I cannot take you up on.

I ordered some apparently genuine Potassium Aluminium Sulphate today so will see how that goes.

I have been using a 'bain marie' arrangement to keep the solution hot but not boiling away. Hopefully using the correct variety of 'Alum' will bring results!

I have had great success using a phosphoric acid solution for rust removal. Fill up the space between tap and s/steel with un diluted acid. Wash out once or twice a day and replace til the remainder of the tap falls out. Not fast but no damage to hours of machining work . Mine was a M4 tap. Always use a new or very sharp tap.

I think it would be worthwhile to keep some small diamond core drills on hand for removing broken taps or drills. Example:**LINK**