papak Posted April 25, 2018 Share Posted April 25, 2018 Okay, Im getting a little crazy now. I have a new set of Brooklands windscreens from Stafford Components and I am trying to determine the thread size and pitch of the threaded studs that extend from each side of the frame. It's between M8x1.25 and 5/16x24. I need to remove the stud to true the face of the cast frame but the stud doesn't exactly match either pitch. Is there some weird British measurement in between that I haven't discovered in the last 60 years? I am reluctant to run a die down the threads until I am confident that I know what I have. "Don't execute Plan A until you have defined Plan B"! Anyone else run into this? Link to comment Share on other sites More sharing options...
Tbox56 Posted April 25, 2018 Share Posted April 25, 2018 M8x1.0???? Link to comment Share on other sites More sharing options...
m wirth Posted April 25, 2018 Share Posted April 25, 2018 use a thread pitch gauge that comes with tap and die sets? Link to comment Share on other sites More sharing options...
papak Posted April 25, 2018 Author Share Posted April 25, 2018 I tried a gauge for both standard and metric to no avail. I'm running it by a local machine shop this afternoon. Sure has me scratching my head. Link to comment Share on other sites More sharing options...
sagamore Posted April 25, 2018 Share Posted April 25, 2018 Could it be Whitworth? (link) Link to comment Share on other sites More sharing options...
papak Posted April 26, 2018 Author Share Posted April 26, 2018 Sure enough, Whitworth! Go figure. Link to comment Share on other sites More sharing options...
coffee break Posted April 26, 2018 Share Posted April 26, 2018 You're keeping me in suspense, what's the dia. and pitch? (thread type aside) Link to comment Share on other sites More sharing options...
inchoate Posted April 28, 2018 Share Posted April 28, 2018 Sure enough, Whitworth! Go figure. BSW and BSF have a 55° thread angle so you can't really read a good thread pitch with a 60° SAE or metric thread pitch gauge. If you are going to deal with british cars a whitworth thread gauge is a good tool to have lying around. my rule of thumb is that if you can't get a read on it with a regular gauge it's probably british. things get really interesting when you get into the BA fasteners which have a 47.5° thread angle. then there's BSC, BSPP, and BSPT. the brits were quite fond of creating screw thread systems for specific applications. i'm a big hit at parties. Link to comment Share on other sites More sharing options...
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