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Source for #10 x 40 Machine Screw?

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  • Source for #10 x 40 Machine Screw?

    Hi All,

    I am refurbishing an old B&S Dividing head and a split plate on the side near the crank is held in place with four flat head slotted machine screws. The heads on three of the screws have broken off and I was able to get them all out. The problem seems to be that these are not standard size screws.

    The screw mics out around .183 which is the approximate size of a #10 screw but my pitch gauge and my tired eyes show it to be 40 TPI. The head on the one remaining good screw does not seem to be as large as a standard machine screw either. In any event, would anyone know of a source for these uncommon machine screws? I am guessing I might have to tap the holes in order to use a more common screw if I cannot find replacements? I sure would hate to do that...

    Many thanks to all,

    Joe...

  • #2
    Not sure where you could get the screws, but why not make them? If you don't want to single-point them in the lathe, JTS has a die for less than $10.

    http://www.jtsmach.com/jtswebshop/Taps_Dies/T125.asp

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    • #3
      10-40 might be used in gunsmithing.

      Comment


      • #4
        Thanks, it seems making my own might be my only option.

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        • #5
          Originally posted by macona View Post
          10-40 might be used in gunsmithing.
          I thought the same thing and checked Brownell's and almost every other hit in Google. Looks like I will have to make my own...

          Thanks for your help,

          Joe

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          • #6
            It's fun, too. http://metalworkingathome.com/?p=40

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            • #7
              Do You have any local friends who build small model steam engines?

              Originally posted by dp View Post
              Many who build small model steam engines use 40 tpi taps and dies to make small fittings, 3/16" by 40 tpi is a common thread. beware, they are available both in 55 degree ( Whitworth ) or 60 degree( North American) thread form. Many model makers suppliers stock them. The two thread forms CAN be made to fit each other by very slightly squeezing in split dies, thus producing slightly undersize male threads, not correct in theory, but a quick answer for a hurried repair. Hope this helps David Powell.

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              • #8
                Originally posted by dp View Post

                DP, Thank you, very informative and I do appreciate it.

                Joe

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                • #9
                  Originally posted by David Powell View Post
                  Many who build small model steam engines use 40 tpi taps and dies to make small fittings, 3/16" by 40 tpi is a common thread. beware, they are available both in 55 degree ( Whitworth ) or 60 degree( North American) thread form. Many model makers suppliers stock them. The two thread forms CAN be made to fit each other by very slightly squeezing in split dies, thus producing slightly undersize male threads, not correct in theory, but a quick answer for a hurried repair. Hope this helps David Powell.
                  Hi David, it is very helpful.

                  Thank you,

                  Joe

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                  • #10
                    Recently bought a 3/16-40 tap and die from PM Research http://www.pmmodelengines.com/shop/t...ead-taps-dies/

                    Very good quality.

                    Geoff

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                    • #11
                      I thought some photos might prove to be helpful.






                      Last edited by jbacc; 08-23-2014, 09:36 AM.

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                      • #12
                        Why not go to Brown & Sharp? They, and Lufkin Are very good with replacement parts. Four screws shouldn't cost too much. Bob.

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                        • #13
                          Brownell's also has screw blanks so you can put your own threads on them. That way you can just turn to size if needed, thread and you're done.

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                          • #14
                            I just found a sight that might be a source of good information on this subject.
                            <http://www.efunda.com/designstandards/screws/unified.cfm>
                            It lists a 10- 40 UNS thread and gives all the specs. for it
                            Larry - west coast of Canada

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                            • #15
                              From a web search for "machine screw 3/16-40":

                              http://www.adelfastener.com/
                              http://www.adelfastener.com/customer...2254076570.pdf

                              About 1/4 down the page they list 3/16-40 (3/16 = 0.1875")


                              These guys have then, but you gotta buy a few:

                              http://www.shamrockexpress.com/screw...c-0503mpp.html

                              Perhaps they could supply the name/address of someone who has purchased them and who would sell smaller quantities. Or perhaps you could ask for samples.


                              A search for "machine screw 10-40" also brought many returns.
                              Paul A.
                              SE Texas

                              Make it fit.
                              You can't win and there IS a penalty for trying!

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