Form or cut tap for chasing tight threads in nickel plate brass?

[richard newman]

I use a lot of nickel plated brass hardware on my banjos, and often internal threads need to be chased because they are too tight. Threads range from 6-32 to 10-24. sometimes 8-26 (custom made taps)

I've been using cutting taps, but wonder if I should be using forming taps? Seems the nickel should be tough on cutting edges. I really like the form taps for stuff I make, especially in blind holes.

 

[52 Ford]

I'd try a forming tap, since the threads are already cut in and you just need to "loosen them up".

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[crossthread]

Sometimes you can loosen up a thread that small by wrapping steel wool around the tap and going at it a few times.

 

[Mtndew]

If it were me, I'd use a cut tap to chase the threads.

 

[Larry Dickman]

if you're already having custom taps made, why not have them ground to an H5?

 

[adh2000]

Short piece of threaded rod in a cordless drill plus some clover compound. Clean up is a pain.


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[52 Ford]

Short piece of threaded rod in a cordless drill plus some clover compound. Clean up is a pain.


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True. I used that technique on a big threaded hole in a welded part. Turned sorta oval shaped after welding. I needed it to turn smooth and didnt have a tap that large. Couple minutes with some aluminum oxide compound and a bolt and it's butter smooth.

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[richard newman]

Tbanks for the replies. These are parts sorta like fancy acorn nuts that I'm buying, not my tap that's causing trouble. Cut tap chases them just fine.

If I start making these myself, I'd drill and form tap after plating. Better threads and no crap stuck in the blind holes.

 

[52 Ford]

Tbanks for the replies. These are parts sorta like fancy acorn nuts that I'm buying, not my tap that's causing trouble. Cut tap chases them just fine.

If I start making these myself, I'd drill and form tap after plating. Better threads and no crap stuck in the blind holes.

Right. In something like brass, especially with an already cut tap, and especially especially in a bind hole, a form tap aughtta be quicker since you aren't making chips. Plus wear isn't much of a concern.

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[EPAIII]

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In case any others were wondering.

 

[52 Ford]

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[boslab]

Use an oversize plating tap when tapping the hole, saves the effort of recapping
Mark

 

[Isberg]

Thanks, I did not know plating taps existed. Had grievous problems with small nickel flakes on my plated sensor housings after cleaning up threads. These small flakes can be very difficult to get rid of and do no good to sensitive electronics...

 

[jim rozen]

Yeah we're in the middle of this at work. M1 tapped holes in copper. Then gold plate. The stick the screw halfway into the hole before it binds up. Then strip out the allen head on the screw. Fun and games.