Question for George or a Fray brace expert

[Cody Cantrell]

I just won an auction on the bay for a Fray brace. It is missing the original thumbscrew. My question is what type and size are the threads? Is there some type of available thread pattern that works? I could forge the thumb screw part but need help with the threads (I noticed on the Fray brace that I own that the threaded portion is pinned to the thumbscrew). Does anyone have any other solutions to this problem? Thanks for any help.

[george wilson]

I'm not an expert on braces. I'd have to see the screw,measure it,etc.,and make a thumb screw to fit whatever the thread is. I do that all the time on mechanical antiques. Do you know what the thumb screw is supposed to look like? Might not be worth the money to make one from scratch. Perhaps an existing OLD thumbscrew could be re threaded and modified to work. I have a cigar box full of old thumb screws.

[Mike Henderson]

I'm not a Fray brace expert but the thumbscrew on mine is 14 threads per inch. The outside diameter of the thumbscrew is about 3/8". I forgot to measure the length of the threaded portion.

Regarding the type of threads, I don't know thread types but here's a closeup of the thumbscrew.

Mike

256056 256057

[Jim Neeley]

Beautiful tool porn, Mike! :-)

[george wilson]

Standard 3/8" thread is 16 and 24. The threads on that thumb screw are not cut to standard diameter,either. Those threads are shallow. Trouble is,exactly how shallow.

[Cody Cantrell]

Thanks for posting the pic Mike. I think the O.D. was .390", not sure on the minor diameter. The threads look like acme threads. Any idea how to replicate that George? Anyone else have a good solution to this problem?

[Chuck Nickerson]

Anyone else have a good solution to this problem?

A quick solution is to get a thumbscrew smaller than the existing hole, then epoxy a matching nut to the frame.
This works now but doesn't alter the threads if you ever get the correct screw.

[Mike Henderson]

Beautiful tool porn, Mike! :-)
Yeah, I have to admit it's one of the better looking old Fray braces. I was lucky to find it. Most of those old braces were put aside in a barn or somewhere and they developed a lot of rust. Still usable but not as nice looking.

My guess is that when reliable ratchet braces with good chucks became available, people migrated to those and left these older non-ratchet braces in storage. Like today, people wanted the latest and greatest tool.

Mike

[george wilson]

They aren't Acme threads. They just aren't cut to full depth. Acme threads have flat spots in the minor diameter of the threads,the same width as the flat tops of the threads,and the angles of the threads are 14 1/2º. It would not be difficult to make that thread,but it needs to be fitted to the actual brace. .001" too big,and it won't screw in. A teeny bit too small,and the thread will be wobbly.

[Tom Vanzant]

Could be 7/16"-14 threads cut in undersize shank?

[george wilson]

Not if the major diameter is .390.

[george wilson]

If you send me the brace with return postage,I'll make you a screw that will fit it. I'll rough out the head with a bandsaw so you can finish filing it up,but the threads will be perfectly finished. I can saw the thumb part flat and rough out the shape. I can turn the collar part,too. This will be a favor. My work is either very expensive or free!!:)

P.S. maybe you could take the head off the brace and get it into a smaller package.

[Cody Cantrell]

Thank you George that is a very generous offer

[Tom Vanzant]

George,
If a 7/16-14 die is run onto a .390 dia shaft, the resulting thread would have large flat crests and sharp roots like the thumbscrew in question. It's not a 7/16-14 thread, just a non-standard (today) thread possibly created as I stated.

[george wilson]

When I get an original screw,I'll just measure it and copy. No problem if I have 1 to measure.

[Cody Cantrell]

Just tried the 7/16-14 die on a .393 rod and the minor diameter of a 7/16-14 is larger than the minor diameter of the thumbscrew, so the threads are to wide.

[Mike Henderson]

I went and checked the screw on my Fray brace again to make sure it's 14 TPI - it is. But it occurred to me that maybe some of the Fray's used different thumbscrews. Just a reminder to check the one you have before you make a 14 TPI thumbscrew.

Mike