donmarkey Posted January 18, 2006 Author Report Share Posted January 18, 2006 I got the M4x.7 screws today and they fit pretty good. -Don Link to comment Share on other sites More sharing options...
tinkerfive Posted January 19, 2006 Report Share Posted January 19, 2006 OK I'm man enough to admit when I'm wrong. It is 36tpi not 32tpi. I've got to believe that the 6.5 thread pitch just happens to be equivilant to 36tpi. While Paul may have done the first draft in metric (read on) I still believe that all threads are cut as TPI. At one point I came to realize something that supports the 'first draft' idea above. I wondered why the small ring OD was .98 ( the large ring minor dia is .98 too ). Why didn't Paul just make it an even 1" ? Then I came to realize that .98" almost exactly = 25MM. So I think that Paul did indeed do the first draft in metric and just converted to the english equivilant when the design was to be made on English equipment. Tinker Link to comment Share on other sites More sharing options...
carzngunz Posted January 19, 2006 Report Share Posted January 19, 2006 I'm not sure that any of these screws were designed as metric. As someone else already stated screw sizes weren't very standardized back then. It could be that Paul just designed the screw to do the job at hand. 4mm is 5/32" and .7 pitch is 36 tpi. Maybe just a coincidence. I'm not sure about the 6.5 pitch either but I'm not going to search for one just to try it out. I'm not sure about this, my history is kinda weak, but I think that the numbered machine screw sizes were an American invention after the turn of the century. Either way I believe that if you need to clean up some threads or even thread a new screw a 4mm-.7 split die will work just fine. Afterall it has a couple of things going for it. It fits and the dies are cheap and easy to get! Not to mention the fact that none of my screws fit tight into the threads of my bolt stops anyway! Link to comment Share on other sites More sharing options...
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