View Full Version : Tap removal

26-07-2015, 02:09 PM
Further to my recent RFQ on removal of a tap from a machined aluminium part, I received a couple of PMs suggesting using a chemical etchant to remove the broken tap.

Yesterday, I managed to devote some time to the problem.

This was the part, with an M3 tap stuck in the middle hole. It appears this was to have been the last operation on this piece, as is always the way:


You can just see the pointy end of the tap poking through at the end of the slot:


With the aid of a 2.50 aluminium pan from Asda and a solution of BTR-10 Tap Removal Powder, I set it simmering yesterday afternoon.


Once it was up to temp, you could clearly see the bubbles emanating from the reaction with the tap:


It took several hours, but then I did keep removing to check on progress. One worrying factor was that parts of the aluminium also appeared to be fizzling but it doesn't appear to have affected the part.

Once washed and dried, I was able to complete the thread in the hole. The end is a bit bashed around from previous attempts to drive the tap out, but I think it will be perfectly serviceable.


26-07-2015, 03:38 PM
Good to hear you've got it sorted, and excellent to see you share the solution to help any future machinists searching for a similar solution,

27-07-2015, 09:25 AM
Glad you got it sorted, do you have a link to the powder used?

I'm sure that I'll be in the same situation in the near future..... My solution when I broke a tap in the top plate of my gantry, was to drive the broken tap through and use a bolt instead of tapping as I could get to the underside and the nut isn't in the way.

27-07-2015, 09:37 AM
Thats really cool, never knew such thing existed. Hopefully ill remember when i have the same problem.

27-07-2015, 10:46 AM
Couldn't find the product mentioned but try this link
http://www.tap-die.com/contents/en-uk/d296_Tip_Remove_Broken_Tap_Drill_Reamer_Tap_and_Di e_Co.html

30-07-2015, 09:12 AM
The powder I used was purchased from a company called TransLunar Technologies, back in 2009, but they don't seem to exist any more :(


30-07-2015, 09:41 AM
Nice find Adrian
I have been in Engineering for 50 years and never come across that one,good news is Alum should be pretty easy to get hold of.

Crazy L
31-08-2015, 05:43 PM
Wow, Awesome, I've never heard of that one and I've worked in some right old school shitholes in my time. Normally it's the old boys who share this stuff.

Robin Hewitt
01-09-2015, 04:28 PM
Amazing, I typed into google, "Alum dissolves" and "steel" popped up on the drop down menu :beer:

I never knew that.

Then I tried typing "dissolves steel" and "alum" was the only real suggestion.

01-09-2015, 09:13 PM
Not seen that one before. Only seen spark erosion for removing taps (from steel I think).

Clive S
01-02-2018, 07:01 PM
Ok after making this for a HTD belt.23701 upon drilling & tapping for the grub screws the tap broke full depth so I had a go with alum. 23702
it took 500g of alum and 12 hours on the induction hob (the dish was on a piece of 3/8 steel plate) in two sessions at just below boiling point and having to keep it topped up with water ever 45min.

Result tap was dissolved completely but did discolour the aly a bit, I could have made a new one quicker but wanted to try out the procedure. If I had to do it again I would have use a much deep container and suspended the part on a copper wire.

01-02-2018, 08:32 PM
12 hours on the induction hob

Your not married, are you!?

Mine (the wife) complains if I even try to cure dry-film solder mask in the oven.


01-02-2018, 08:36 PM
If I had to do it again I would have use a much deep container and suspended the part on a copper wire.

This -


Use a 3L pop bottle to keep it topped up unattended

Clive S
01-02-2018, 08:43 PM
Your not married, are you!?

Mine (the wife) complains if I even try to cure dry-film solder mask in the oven.


Ah Yes, You need somebody to keep an eye on it to make sure it was topped up:nightmare:

01-02-2018, 11:10 PM
Nice post Clive glad it worked out. You might remember me messing about with alum to remove a broken tap without much success. I think keeping it hot must have helped you which I think you advise me at the time (?) but I couldn't get near the hob

Luckily I don't break taps any more (ahem) . . .