Sheffield brace button mechanism rebuild

[Matt Groves]

Hi all, I just acquired a wooden brace in the Sheffield style, unlabeled maker, like an Ultimatum style perhaps, that uses a button mechanism to hold the tapered square shank bits in. It seems to me there is a piece missing in the bit-holding section, a piece that would normally have a tab to catch the notch of the bits, and that the button would release. Right now, there is nothing that would hold the bits in, and I can't find any visual reference of how the mechanics are intended to work. I'm sure I could fabricate a replacement part if I could find an example, but I can't figure out what action is happening, since pushing the button inward is the same direction the notch has to move to release the bit... definitely not a see-saw pivot, more likely an end pivot lever action or something. A screw high up on one side of the brass end is very suspicious to me as to how the missing piece might have been anchored, but I make no assumptions. If anyone possesses a similar button brace and wouldn't mind sharing some info about the internal mechanical action (even better if you could share a picture of the pieces disassembled and what's missing), or know of anywhere on the web where that is documented, I'd be very grateful. I'd really like to make it as true to original as I can.
Thanks!
Matt
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[steven c newman]

IF you can find the drawings from the Patent pages...as to what parts he used...perhaps that MIGHT help..

[Matt Groves]

Hi Steven, I attempted that, but could only find a pretty sketchy drawing (pun intended) referenced here: http://chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.htpaa.org.au/images/TC/TC_025_Feb_1993_V5.1-page_10-18.pdf and either it's not clearly visible to me or the original didn't have a button... but I can't figure it out. Patent #12377 John Cartwright 1848, sold to Marples who then made the Ultimatum brace... but I haven't been able to find a patent diagram that shows the button cross section. So close, yet so far away...

[Jim Koepke]

This one looks similar to yours:

505351

The long piece is also the spring. The hooked end goes through the larger square to grab the notch on the bit. The tang on the bit can be filed to fit more securely in the chuck.

The coil spring on yours looks to be a 20th century attempt at repair.

jtk

[Matt Groves]

Thanks Jim, that piece is what I was trying to figure out. I had a feeling my spring piece wasn't original. Would it be possible to get one more pic of those pieces reassembled in the brass piece? How is the long piece anchored at the top to function as a spring? Thanks so much!

This one looks similar to yours:

505351

The long piece is also the spring. The hooked end goes through the larger square to grab the notch on the bit. The tang on the bit can be filed to fit more securely in the chuck.

The coil spring on yours looks to be a 20th century attempt at repair.

jtk

[Jim Koepke]

Thanks Jim, that piece is what I was trying to figure out. I had a feeling my spring piece wasn't original. Would it be possible to get one more pic of those pieces reassembled in the brass piece? How is the long piece anchored at the top to function as a spring? Thanks so much!

I am not sure I have all the other pieces. Next time out to the shop I will take more pictures.

The long piece has a hole, near its top, to mount it using one of the screws to hold the chuck (shell) in place. My memory is a little vague on this one but I think there was a metal piece through the wood and threaded for the screws holding the brass shell (chuck) to the bit stock. The top of spring was trapped between wood (metal sleeve?) and one brass strap on the opposite side of the button head.

jtk