Small broken taps blind hole fix easy

[Team ricky]

Hello gents,

I thought I’d share how to remove a broken tap in your nice new shiny part you don’t fancy scraping

As long as the part is non ferrous or stainless steel thus trick will dissolve that pesky tap no machinery or damage to the threads / main part every time !

The solution is ‘Alum powder’

Mix 50-75 grams in 500ml hot water (80-90c)

Stir well then put your part in fully submerged in a plastic container lid on…

If you have an outside heat source you can maintain 80-90c to speed up the reaction dramatically…
In this condition an M2 tap will disappear in 2-3 hrs completely

If you wrap the container to keep the heat in 1 day whilst occasionally de-canting and re-heating works too!

I found the powder on EBay £2.99

Works a treat every time !

YouTube has some vids too which explain further

[Kim]

Yeah, I've had some marginal success with the old alum trick also.  It takes a while, but as you say, keeping the solution warm helps speed up the reaction. But still, it's not fast...

So what part did you break a tap in?  I've done it more times than I'd like to admit. 

Kim

[crueby]

For faster removal and in other metals, I usually use the old dental bur trick - high speed dentist-type air rotary tool with very small diamond coated burs, and cut out the center section down the center of the broken tap. Then the threaded parts around the outside can be picked out.


Not that I've broken taps. Today, that is!      Usually right after noticing that its not cutting as easily as normal, and thinking 'hmm, this tap may be getting dull (SNAP)'   


Have broken fewer since getting a tapping stand, but still happens when they are getting dull or if I dont use enough oil or dont clear chips or dont notice its bottomed out in the hole or any of the other umpteen reasons!

[pirmin]

if it is a hss tap, u can drill with carbide and hammer it out with a small chissel. it takes forever but it works and if done corect you end up without any harm to the part. ( i have done that with a M1 Tap . even more fancy when your M1 Threaded rod breaks in the die and you have no stubby end to hold on, i had to make a tiny tiny carbide boring bar and was able to bore it out.

I also have Alum Powder , but i think it would be fair to say that it only works in aluminium  or Non Feric metals ,or am i wrong ?

For People who Do Break a lot of Taps, i recommend you Guys to buy a set m1 Taps or 8 BA , and Practice 
After i broke Two! m1 taps in a row , it never ever happend to me again sicne then. in my 3 years of machining ( Daily) i have broke 3 Taps so far

[Team ricky]

My tap was in a Bronze cylinder casting so Alum is the way forward! Pretty much no risk to the part which is why I went with it and used patience

[Jo]

It is always good practise to use a nice sharp tap when cutting bronze castings. Bronze grabs drills and snaps old taps 

To an extent that it is worth using a fractional bigger tapping hole in bronze as well as plenty of lubricant.

Jo

[crueby]

For bronze bar stock, I much prefer working with the Bearing Bronze alloys, the Silicon Bronze is really sticky stuff as Jo mentioned. For castings, not much choice!

[mcostello]

There are at least 4 different kinds of alum. Make sure You get the right kind.
I left an aluminum part on the wood stove for a couple of days till i found it out.

[Admiral_dk]

There are at least 4 different kinds of alum. Make sure You get the right kind.

Do you happen to know the Chemical Formula for the correct/good one - it would help other tremendously in locating the right stuff 

Per       

[uuu]

Here's a Wiki article on the stuff:  https://en.wikipedia.org/wiki/Potassium_alum

Wilf

Edit: and an article on all alums, including the wrong ones: https://en.wikipedia.org/wiki/Alum

[crueby]

There are at least 4 different kinds of alum. Make sure You get the right kind.
I left an aluminum part on the wood stove for a couple of days till i found it out.

Ah, that would explain why the one time I tried it, it didn't work!  As Per asked, how do we find the right version??

[gipetto]

from wikipedia

Alum in the form of potassium aluminium sulphate or ammonium aluminium sulfate in a concentrated bath of hot water is regularly used by jewelers and machinists to dissolve hardened steel drill bits that have broken off in items made of aluminum, copper, brass, gold (any karat), silver (both sterling and fine) and stainless steel. This is because alum does not react chemically to any significant degree with any of these metals, but will corrode carbon steel. When heat is applied to an alum mixture holding a piece of work that has a drill bit stuck in it, if the lost bit is small enough, it can sometimes be dissolved / removed within hours.[33]

that's all it says, the rest is about other uses such as antiperspirant.

Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound first found mentioned under various Sanskrit names in Ayurvedic medicinal texts such as Charak Samhita, Sushrut Samhita, and Ashtang Hridaya; is chemically defined as the double sulfate of potassium and aluminium, with chemical formula KAl(SO4)2

Ammonium aluminium sulfate (NH4)Al(SO4)2

[crueby]

But what do they call it in the stores?

[Jo]

People from India use it a lot and they call it Fatakdi Powder, we call it Alum Powder, either way it is crystallized potassium aluminum sulfate and you find it on Ebay or in the Eastern food stores.

Jo

[bent]

...exactly what kind of food would use that?

Never mind, don't want to know.  I'll ask my #2 son, he's back home from travelling the world, including the middle East.

Having #2 son home this summer, we have explored a variety of ways to cook wild rabbit (Mom gave us permission to go full Ukrainian on the Rabbit Invaders of her garden), and agree the Maltese recipes are some of the best.  Pressure cooker is also top of our list.