What's new
What's new
By:
Advanced search…

dissolving HSS CO tap in alum

M

madmachinst

Stainless
Joined
Jan 15, 2007
Location
Central FL
ttitle says it all, and I'm not ashamed to ask this question again for the 10,000th time. You see the tap that I managed to break is 2-56 in 7075. Now some say Muriatic acid and some say Nitric acid? What have you gotten the best results with and where did you get it. You guys are the best. Imagine having to scrap a piece after 4 hrs work and on a weekend. Sometimes I wish I was employed.
John W.
 
Either acid will also damage the part.

If it is a through hole I'd take it to someone with a wire EDM to cut out the tap. Second choice would be someone with a die sinker. I'm not sure if they can go that small with a copper anode.
 
John, if the part could be put through an anodizing bath, I think I have read that the broken tap will be gone when it comes out, with no damage to the aluminum. I think that may be mild sulfuric acid.
James
 
The strongly oxidizing acids (sulphuric and nitric) will not damage the aluminium. The oxide film they form on the metal is self-protecting. Hydrochloric will damage aluminium because it does not reinforce the oxide film and aluminium chloride is soluble. Alum is equivalent in effect to very dilute sulphuric.

I've only used dilute nitric, but the results were excellent. You do need a method of circulating the acid to stop it from getting used up in the hole and the reaction stopping.
 
do you mean like a recirculating pump. Now I already bought some alum at the ace ( the garden variety) If I was to leave the part in a saturated soln of that, would it work? Time is not the issue here.
 
alum

If you can get the part to fit in a pan of water and have a heat source to get it up to a simmer that will do it. was making connecting rods for a panther pup recently and broke a 4-40 tap in aliminum connecting rod. put in a pan and added alum and simmered about 4 hrs. the rod was discolored but shined up fine. tap turned into sludge in hole. steve
 
Did a test run on a piece of 7075 HSS and hot roll ( ACE mystery metal rod). After an hour The HSS was reduced from .192 to .188 and the hot rolled shank was reduced from .375 to .360 while the 7075 didn't shrink a bit. This process will involve a lot of scraping and cleaning in order to introduce fresh metal as opposed to rust. Also I was at about boiling temp with supersaturated soln. My only concern s that cobalt HSS will dissolve much slower than regular HSS. Will et everyone know how this went. EDM guy wanted $60.00 ( what a nut)
 
$60 seems cheap to me if you want to save the part that badly. How much is your time worth? You'll blow 60 bucks screwing around with your acid/alum/magical mystery solutions.
 
Dcrouch said:
$60 seems cheap to me if you want to save the part that badly. How much is your time worth? You'll blow 60 bucks screwing around with your acid/alum/magical mystery solutions.
Click to expand...

What he said. Hole pop it or find someone close with a tap burner.
 
$60 seems cheap to some one who makes at least that much an hour. It's highway robbery for that much money in 10 minutes (rather insane if you ask me). I'm selling the finished product for $70 when I get geared for production, my buddy gets his for $50 ( he gave me the general idea in the first place). So no, $60 is not cheap. The only thing cheap here is my time.
 
madmachinst said:
$60 seems cheap to some one who makes at least that much an hour. It's highway robbery for that much money in 10 minutes (rather insane if you ask me). I'm selling the finished product for $70 when I get geared for production, my buddy gets his for $50 ( he gave me the general idea in the first place). So no, $60 is not cheap. The only thing cheap here is my time.
Click to expand...

That's understandable... $60 is a lot for someone who has a hole popper... Was that his price for that method? Was it a wire shop?

If it only took you 4 hours to make, maybe it would pay to start again and be more careful tapping?
 
How about this And the results are in 1/2 gallon of water with supersaturated soln of alum, 10 drops of muriatic added for good measure and stovetop with knob set at med med low (7:30) within two hours time ( mind you I was not tending it all the time only every 15 mins) the HSS CO tap was DISSOLVED . That wasn't even worth $10.
 
madmachinst said:
How about this And the results are in 1/2 gallon of water with supersaturated soln of alum, 10 drops of muriatic added for good measure and stovetop with knob set at med med low (7:30) within two hours time ( mind you I was not tending it all the time only every 15 mins) the HSS CO tap was DISSOLVED . That wasn't even worth $10.
Click to expand...

Interesting.. That's great. I'll have to remember that for the future if I ever face that problem. What was the condition of the aluminum part when finished with all this?

This forum is great.....:) Always something new to learn.
 
You must log in or register to reply here.

Similar threads

S
Advice on moving our prototyping work in-house with a Brother Speedio?
4 5 6
Replies
100
Views
30K
SVFeingold
S
A
Broken Tap & Alum
Replies
12
Views
6K
Jeremy K
J
G&L4nahalf
How to tool up for under 100$
4 5 6
Replies
115
Views
22K
G&L4nahalf
G&L4nahalf
P
Outsourced Job Moves In House to Save Money
Replies
0
Views
4K
PracticalMan
P
jhe.1973
OT? Shop tip – Removing a broken HSS tap w/TIG welder
Replies
8
Views
4K
eKretz
eKretz








 

ABOUT PRACTICAL MACHINIST

With more than 10.6 million unique visitors over the last year, Practical Machinist is the most visited site for metalworking professionals. Practical Machinist is the easiest way to learn new techniques, get answers quickly and discuss common challenges with your peers. Register for the world’s largest manufacturing technology forum for free today to stay in the know.

Learn more about us.

STAY CONNECTED

Facebook Instagram YouTube LinkedIn Pinterest Twitter Tiktok

Register Become a forum member. Register today.

Sign Up Sign up for our e-newsletter.

© 2024 Copyright Practicalmachinist.com. All Rights reserved.

Back
Top