Removing Broken Tap

[ianjParticipant @ians]

 

 

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

[Tim StevensParticipant @timstevens64731]

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

[old martParticipant @oldmart]

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.

[John Paton 1Participant @johnpaton1]

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!

[Kevin DParticipant @kevind]

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.

[John ReeseParticipant @johnreese12848]

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

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