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Source For Odd BSW Tap Needed

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AN5Sprite

AN5Sprite

Jedi Knight
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Anyone know where I can find a 7/32" x 20 tpi BSW tap? I'm restoring an old Stanley woodworking plane and I need to chase out some threads in the plane's casting.

I've found 7/32" x 24 BSW and 1/4" x 20 BSW but not the odd 7/32" x 20. I'd rather not tap out to the more common 1/4 x 20 because then I'll need to make up new bolts/nuts etc.

I'll consider any source; new, used, part of a kit, bottom of your toolbox lend/lease/buy/barter. I'm just looking to do this right.
 
I consulted several very complete thread charts, and none of them list 7/32-20 in British Standard Whitworth threads. Are you sure that's what you have?

If so, one solution would be to have someone with a lathe make you a tap. If you only have a few to do, it can be ordinary carbon steel. Single-point the threads, then grind the flutes and the starting taper. I've done it myself to chase oddball SAE threads.
 
Like Randall, I am not familiar with this size thread. But if you can find a 7/32" x 20 tpi bolt, you could always grind flutes along its length and use it (with plenty of oil) to chase the threads out. I'm made home-brew "taps" like this on occasion and if the threads aren't too bad, it may work.
 
I'm sure it's 7/32" x 20 BSWhitworth 55 degree. Confirmed it with the scholars. Stanley adopted this as standard on their "Bailey" planes mid 19th century and kept it that way for more than 100 years.
Out of all the planes I have (many) I've only got one where the screw that holds the front knob on seized in the iron plane body and I snapped it off trying to remove it. It's a plane made during WWII when they had to change materials, no brass and the steel isn't as good either.

There was a company in California that was selling the taps/dies up until MSC bought them. Once they merged MSC dropped the less usual sizes.

There has to be one out there, somewhere...

Is this an easy project for someone with a little know-how and and a small bench top lathe? I'm not going to bother my local machine shops. I already know the answer I'll get.
 
Don't mean to start an argument, just trying to help ... it seems that there is considerable disagreement on that point. Many folks seem to believe that they are #12-20 threads. Eg,
https://lumberjocks.com/donwilwol/blog/24090
and the articles it links to.

Not a difficult project, if you have the gears to cut 20 tpi. I'm definitely a rank amateur with a lathe, so if I can do it, anyone can.

But ISTR that with the Sherline mini-lathe, you have to crank the spindle by hand; it can't cut threads under power. That was a long time ago, though, so maybe no longer true.
I used a Grade 8 bolt as a blank and didn't try to anneal or harden it. Worked out well for me, although the resulting tool was ugly, it did the job. But I only had two sets of threads to chase, it might wear out if I had a lot of them to do.
 
No argument. The interwebs are, as always, confused and contradicting themselves. :crazyeyes: is what I feel like trying to follow some of these guys. #12 screw = .216" = 7/32" 20tpi. As long as the thread pitch is 55 degrees (BSW)...
 
Link didn't work for me.
Unless you have to have the secret code
 
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