broken bits

[grumpygrady]

here are a few posts from the anodizing group about broken taps
i hope this helps
my tanks are not set up yet or i would try it and see


I've read that a steel tap that's broken off in a part will dissolve away during
the anodizing process. One of the larger parts I need to anodize does in fact
have a broken 4-40 tap stuck in it, but I don't want to contaminate the
anodizing bath. Can the tap be dissolved just by soaking the part in non-diluted
battery acid? Or is the electrical process of anodizing necessary in order to do
this in a reasonable amount of time?


Re: [anodizing101] Re: Dissolving a Broken Tap


..I have also used the nitric acid to dissolve thread forming taps from aluminum. The stuff I used was a kit called 'Tap-Out' sold in machine tool shops...it had the acid, some clay to build a 'dam' around the top of hole, and some pieces of stainless steel wire, used to agitate the acid every few minutes..
The acid is a mixture of Nitric acid and alcohol...called nitol...it's only about 20-30% acid. You can buy nitric acid at a laboratory chemical store, but it will be a solution of nitol...nitric aid is very corrosive....even at the 20-30%...and cannot be mixed with water as a storage ...
I don't know the why of how it works, but doesn't attack the aluminum to any degree.
Nitol is very slow to dissolve tool steel, which is why it's not usedin machine shops in lieu of EDM....and hole must be sealed at the bottom of course for nitol.


Jack,
I have anodized a bunch of taps out. I have never tried it with just acid. What I would suggest is to setup as small a tank as you can to get the tap out and keep that acid separate from your anodizing bath.
Regards, Ray

[grumpygrady]

sorry just saw that the tap was in steel
thats what i get for not reaDING EACH POST UNTILL THE END OF THE THREAD LOL

[ihbuilder]

Originally Posted by grumpygrady

sorry just saw that the tap was in steel
thats what i get for not reaDING EACH POST UNTILL THE END OF THE THREAD LOL

no you are right , I'm always braking taps in aluminum . mainly 2-56 . I sorta hijacked when trying to help Clyde with a broken drill bit in steel . this getting broken taps out of aluminum is a big help .

[td9clyde]

Originally Posted by ihbuilder

no you are right , I'm always braking taps in aluminum . mainly 2-56 . I sorta hijacked when trying to help Clyde with a broken drill bit in steel . this getting broken taps out of aluminum is a big help .

It's all good we all or at least both of us learned something lol