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Starting a Chinese Die

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Downwindtracker2

Super User
I was making some inletting pins for glass bedding three different systems. One end is threaded to match the target system and the other end 1/4' UNC for a wing nut , both sets are 1/4". The 1/4"x 32tpi, a special fine, went great. Both dies are KBC house brand made in Poland. However, KBC doesn't sell anything for a 1/4" x 22 Whitworth, so I had to order from Brownells. The Brownell one was a made in China. Twice I ended up with a badly cocked thread. At work I've hand threaded enough, that I have even worn out a die. It was hard starting so for the second attempt I really tapered the lead in. I'm out of 1/4" CRS now. Any tricks for when pick up some more rod?

Before suggesting threading on the lathe, I have never threaded on a lathe before and I would need to make a Whitworth tool bit. My lathe has a 8" chuck and is bit clumsy.
 
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Downwindtracker2 said:
I was making some inletting pins for glass bedding three rifles, two post '64 Winchesters and a Turk Mauser. One end is threaded to match the action , the other end 1/4' UNC for a wing nut , both sets are 1/4". The ones for for the Winchesters went fine, 1/4"x 32tpi, a special fine . Both dies are KBC house brand made in Poland. However for the Mauser action, it takes a 1/4" x 22 Whitworth . KBC didn't sell that size so I had to order from Brownells, a gunsmithing supplier, The Brownell one was a made in China. Twice I ended up with a badly cocked thread. At work I've hand threaded enough, that I have even worn out a die. It was hard starting so for the second attempt I really tapered the lead in. I'm out of 1/4" CRS now. Any tricks for when pick up some more rod ?

Before suggesting threading on the lathe, I have never threaded on a lathe before and I would need to make a Whitworth tool bit. My lathe has a 8" chuck and is bit clumsy.
Click to expand...
Can you use the face of the tailstock as a guide to keep the die perpendicular to the stock?
 
Im not suggesting single point threading, so stay with me. What i normally do is chuck the round bar in the lathe, and use a jacobs chuck with the jaws all the way retracted to press the die square onto the round bar, i then turn the chuck by hand and slowly advance the quill to keep pressure on the die until is gets started

i dont have a die holder for the tailstock, and im under the assumption you dont either
 
I've had what you describe happen if the the stock is oversize for the die. In this case the 1/4"-22 may be "nominal" 1/4" but may actually be just a tiny bit smaller - like .240" or so.
I was trigger by the 22tpi (very non-standard) so did a google search and found this if you haven't:
https://www.k98kforum.com/threads/trigger-guard-screw-thread-size.7831/
about half way down that page GunKraut indicates that he measured a screw at 6.05 to 6.1mm over the threads (my .240" I mention above).
 
I feel foolish, I didn't think to change my order of threading.I can use the crappy die for the short action end.I'll push with the tailstock. I need a section of the rod smooth for easier extraction from the epoxy bedding compound.
 
Whitworth threads were the world standard in the late 1800s. From my college study days, Whitworth threads out side of the strange 55* angle are a good design, the metric and the improved UNC threads both followed his design. As millwrights we have had discussions about thread design, at least Roy and I had.
 
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Not saying Whitworth thread (55° angle and root and crest form) are unusual. What I found unusual is the 22tpi. 20tpi is common UNC and BSW, 26tpi for BSF, 28tpi for UNF, and 32 and 40 tpi for ME (model Engineer), but 22tpi I had never come across.
 
From the LMS Machinist Calculator:

IMG_9215.jpeg
 
Downwindtracker2 said:
Before suggesting threading on the lathe, I have never threaded on a lathe before and I would need to make a Whitworth tool bit. My lathe has a 8" chuck and is bit clumsy.
Click to expand...

I think it's high time you did. It always amazes me how many people are hesitant to try. What can go wrong if you are just learning? Practice practice and practice some more. It won't take long before you love it. I made die holders a million years ago, then I learned how to single point, now my die holders are just trophy tooling.

Also consider making a die holder for your lathe. It's a very easy job and well worth doing.
 
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