Taping A 6x32 Hole In Stainless Steel Round Rod Help

[sgisler]

After you use a form tap in stainless, you will NEVER use a cut tap again. The only time I use a cut tap in stainless is on thru holes where a big burr on the back side will be a problem.

I've been meaning to try those. Is the tap hole size spec the same for cut thread or is increased to accommodate displaced material?


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[Tony Wells]

There are charts for that. The hole is definitely larger. I'm a fan of form taps too. Never had much success using them by hand, but never needed to have. On a machine, the only way to go. On a dedicated tapping machine, the only way to go. No chips to clean out.

6-32 is my least favorite tap. To be avoided if possible. Wrong ratio of thread height to diameter.

 

[Terrywerm]

The holes are larger by a bit. Take a look at the drill chart for roll formed threads in the pdf posted by billh50 in post #20

 

[markknx]

Great info! knew most but learned a little. mostly on form taps. But the tap/drill charts seem off a bit. Looking at 1/4 -20 it calls for 5.1" hole, I could drop the tap though a 5.1 hole sideways. more like a .2010 or 13/64.
Mark

 

[Billh50]

5.1 mm is .201 which is the right drill for 1/4-20

 

[Tony Wells]

1/4-20 UNC form tap requires 5.77mm (0.227) which allows for the proper displacement.

 

[sgisler]

Thanks good info Billh50, thanks. Saved the doc to re-read later. At first glance the mix of imperial threads and metric drill sizes had me scratching my head. But with some thought all should be clear.


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[RJSakowski]

found this bit of tap information and figured someone could use it.

Thanks for posting. This is another one to add to my reference collection.

 

[markknx]

5.1 mm is .201 which is the right drill for 1/4-20

Yes I know this was my point. You should not mix scales. Plus the point of this was exactly why most Americans had a hard time with the metric system. They fix themselves on converting instead of on the ease of work with 10s.
Sorry for the sarcasm. but that was why I added the laughing face.

 

[Billh50]

no problem, just sometimes one has to read things more than once so as not to be confused. But I under stand what you were doing.