Getting aluminium out of fine pitch tap

NaOH or Fe3Cl. The later being not so nasty (except the nice tint on your skin).

Nick

NaOH is probably better - FeCl3 will (albeit slowly) etch steel, NaOH won't.

Yes? Did that recently and had no problems. But it didn't take much time (some minutes) to get the aluminium-smear off (piston ring, the cylinder doesn't count because it was Nikasil coated).

But the "official version" is with NaOH.

Nick

Cheap ultrasonic bath might do it in water. I'm just cleaning a small oil filter in one now.

Joules

It's pretty slow, especially when cold - but people etch stainless with FeCl3 at 50 C.

It's not hugely important in either case, especially if eg you don't leave it overnight - but if you did that with FeCl3 you might not have any threads left, whereas if you did it with NaOH it wouldn't matter - for the steel, NaOH is safer.

Caustic soda eats aluminiuminimum

Oven cleaner.

Tom

...Most of which contain NaOH or something similar.

David

Maybe that was why I suggested it, perhaps..

Tom

Thanks to all for the suggestion. It took me a while to get around to it but the caustic soda worked well.

Thanks Tim

Could someone explain, in small words please, why you couldn't file a groove inside a 4mm nut and screw it on - like a die?

tap a new thread in brass or syeel this will remove ali from threads

MB

-- malbenbu

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I did not try this because some alumnium swarf got stuck in the threads while I was backing the tap out. No parafin (kerosen ?) or working it up or down in small increments would help so I decided to just back it out - I did without incident but it did strip all the threads (of the part)on the way out.

I reasoned that if the tap thread was jammed enough to strip the aluminium thread in the part than there was a good chance that it would break if I tried using a nut to clean it. Also the aluminium in the tap was smoothy formed into the tread with no definate shoulder so I think the nut thread would ride up onto it and jam without disloging the swarf.

Tim