Shop Miscellany #18 Dissolving Broken Taps With Alum

Please Note: I am a beginning machinist and I do not pretend to know everything. Please always operate machinery in a safe manner and if you don't know, find a reliable source. DO NOT COPY ME. I make a lot of mistakes. I provide these videos for entertainment only.

[@Michel-Uphoff]

Hi Robert,
If you want a nice matte finish on aluminum, try a regular household abrasive cleaner (that cheap stuff that you use for bathroom and sink) and a stiff brush. If you work the surface with something like this for a while rotating and scrubbing, you will see that a (dark) gray gunk is formed, that's what you want. After rinsing, you are left with a nice matte "etched" surface. Nothing is as unsightly as the unevenly reflective, mottled surface that aluminum can exhibit. This way you can get rid of it cheap, quickly and harmless, and if you use such a liquid with a lemon scent, it even smells nice ;-).

[@DudleyToolwright]

Thanks for the tip and no caustic chemicals. Almost disappointed.

[@hilltopmachineworks2131]

Cool video. I am glad you posted this topic.

[@DudleyToolwright]

Thanks, Tom. It was interesting.

[@Dogfather66227]

I am more than impressed with your knowledge of chemistry and have to wonder if this might be part of your everyday business background. In engineering university years ago I had three required semesters of chemistry and can barely recall the elemental makeup of water these days. And as it turns out I have never broken off a tap in anything but steel. Interesting solution to a really nasty problem nevertheless. Thank you for sharing this.

[@DudleyToolwright]

My daily gig is oriented towards electrical engineering. I almost went for chemical engineering, but hated labs.

[@TheAyrCaveShop]

Very interesting, I learned something today, Good one Robert !

[@DudleyToolwright]

Glad to hear it. Thanks.

[@i_might_be_lying]

I think EDM drilling method works way faster than that. There's even cheap Chinese portable EDM power supplies made specifically for extracting taps, that you can buy. Haven't tried that myself, but something to look out for.

[@DudleyToolwright]

I believe that you are correct. I will probably try one of those out one day. Thanks for the tip.

[@a-k-jun-1]

I use alum to melt broken off ferrous bolts from nonferrous engine parts. You have to get creative sometimes to keep the bolt submerged

[@DudleyToolwright]

I have seen people use clay dams, but it has to be challenging.

[@marcellemay7721]

The primary ingredient in most of those Thai deodorant stones is potassium alum. Just in case your in a bind and you need some alum, you can just shave some of the deodorant stone to do this if you have one around. I'm not sure that this would be my go to solution for removing a broken tap though. But it might be my last resort solution if everything else failed. I suspect that even just using this solution for a shorter amount of time would loosen it up enough to try and back it out by some mechanical method.

[@DudleyToolwright]

It's also the prime ingredient in styptic pencils for shaving. It is a really slow process and I agree that it would be a last resort.

[@dannywilsher4165]

Interesting, thanks!

[@DudleyToolwright]

No problem!

[@mk6595]

The temperature of the hot plate does not equal the temperature of the solution. There is a lot of heat loss.

[@DudleyToolwright]

There is indeed. The amount was surprising.

[@mk6595]

@@DudleyToolwrightI say this because I've been trying to do this exact thing for the past few days. My hot plate registers 350F-ish, but the solution only 150F-ish. I got some bubbles, and the tap turned black, but after 10 hours I saw no dissolving of the tap. I remade the solution and got no bubbles at all. Tons of bubbles forming on the aluminum, though. I'm not sure what was wrong, but I gave up. I'll spend two hours remaking the part.

[@be007]

interesting video.
does it takes material from the part it self ?
cheers ben.

[@DudleyToolwright]

A little bit. The aluminum got frosted, but nothing too serious unless material surface finish is an issue.

[@FredFred-wy9jw]

18 to 24 hours is nothing when you break tap in an expensive hunk of bronze… I just use a saturated solution, precise measurements not really needed, in a large glass measuring cup on Coffee cup warmer… saved $300 bronze block I was turning into a steam engine cylinder, by why it was 5-40 tap in blind hole

[@DudleyToolwright]

I appreciate you sharing your personal experiences. I always learn something.

[@cowfrank]

212⁰ for those not in Canookastan. Hope that's not hate speech.

[@jeffreyyoung4104]

Be sure to keep your keys by the door so home invaders don't have to look for them!

[@DudleyToolwright]

Imperial as hate speech. Too funny and sad all at the same time.

[@christophercullen1236]

Robert what are you doing to me drawings with Squiggily lines how back to University to do a degree in chemistry and a masters .
20000 thousand on a equipment ,up to the workshop a eyedropper and hydrochloric acid to put on the tap if it damages the part helicoil it .
Kit from down under

[@DudleyToolwright]

Interesting suggestion, thanks. Does HCl work well?

[@christophercullen1236]

@DudleyToolwright very slow helps losing it .