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  • Help with a gear ID?

    I need to replace this gear out of my QCGB, for obvious reasons.



    However, gears and their proper nomenclatures are not my forte`. Apart from knowing it has (had?) 24 teeth, fits a 1" shaft and is nominally 1/2" wide, I don't know what to look for by way of pressure angle or... pitch diameter?

    I'm hoping I can find an off-the-shelf gear I can bore/key to fit in there, but I need to know what to order. I don't know if these photos will help or not, but I'll be happy to get additional measurements if necessary.



    In addition to the above, the teeth measure approximately 0.112" wide (more or less at the base) and going from the peaks of two adjoining teeth to the 'valley floor' is approximately .148".

    Doc.
    Doc's Machine. (Probably not what you expect.)

  • #2
    Looks to me like you have a 14DP 24 tooth 14 1/2 degree pressure angle gear there. Not so common a pitch any more, but searching for 14DP gears may get you something.

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    • #3
      I agree
      .

      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



      Comment


      • #4
        Well that's no help. Nothing in 14DP listed on McMaster, MSC or the recently-noted Amazon Supply. Heck, nothing even on eBay.

        And, naturally enough, I have some 36 Brown & Sharpe involute cutters, but not the one I apparently need. (If I have this right, 14DP, 14.5 degree PA, #5 cutter for 21-25 teeth. I have #1, #2, and numbers 6 to 8. Though no pressure angles listed.)

        Looks like I'll either have to order a cutter or make a single-pointer.

        Why doesn't anyone carry extensive replacement parts for seventy-year-old marques that have been defunct for 20 years.

        Doc.
        Doc's Machine. (Probably not what you expect.)

        Comment


        • #5
          Here is a cutter I believe that you need on Ebay
          http://www.ebay.com/itm/NOS-Decovich...item51a1efb51f

          Harold

          Comment


          • #6
            Eh.. use a number 6 and make it. Might be a bit noisy, but should work. Won't be perfect. It's at the wrong end of the range, a #4 (26 -34) would be closer

            Or, buy the right one and make the gear.

            Seems like the P A should be listed on the cutter...
            Last edited by J Tiers; 01-07-2014, 08:55 AM.
            1601

            Keep eye on ball.
            Hashim Khan

            Comment


            • #7
              Originally posted by J Tiers View Post

              Seems like the P A should be listed on the cutter...
              Usual rule, AIUI, is that no marked PA means 14.5 degrees.

              Just like no marked form on Coventry die chasers means Whitworth form

              Tim

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              • #8
                Doc,
                Thought you might have scored as the 14 DP struck a chord. Drummond lathes use 14DP @ 14.5 PA as change wheels and a while ago I was involved in a project with these machines which involved some gears.

                So dug around and found the relevant tin, rack 5, bin 3, where I had placed it 12 years ago. Like tree rings to date trees I use spiders webs

                However no such luck unless you want 27, 21, 16 or 13.



                You could have had one of these FOC if it had been the right size.
                .

                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                Comment


                • #9
                  Originally posted by Timleech View Post
                  Usual rule, AIUI, is that no marked PA means 14.5 degrees.

                  Just like no marked form on Coventry die chasers means Whitworth form

                  Tim
                  Like the zoology rule I guess, "If there's nothing on the tree, it is the chameleon that you see."
                  .
                  "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

                  Comment


                  • #10
                    try Stock Drive Parts:
                    https://sdp-si.com/

                    Comment


                    • #11
                      This wouldn't happen to be a Sheldon lathe would it? If so look at this gear. It might be worth sending an email to get him to measure the diameter. http://www.ebay.com/itm/Sheldon-Lath...item35d0743b30

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                      • #12
                        Been their done that.You not going to find a store bought gear that pitch,I have looked . Lots of old lathes used 14 DP gears ,but you will have to make it . i have a whole set of cutters in 14 DP just because of that . If you cant find something . PM me and I will make you one .
                        Every Mans Work Is A Portrait of Him Self
                        http://sites.google.com/site/machinistsite/TWO-BUDDIES
                        http://s178.photobucket.com/user/lan...?sort=3&page=1

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                        • #13
                          Originally posted by Timleech View Post
                          Usual rule, AIUI, is that no marked PA means 14.5 degrees.

                          Just like no marked form on Coventry die chasers means Whitworth form

                          Tim
                          Maybe.... these are all marked, I think every one I have is marked....

                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #14
                            Jerry,
                            now look for one that isn't marked and tell us what angle it is ?
                            .

                            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                            Comment


                            • #15
                              I don't have any not marked.... that I know about.

                              But I'd have to probably do some pretty tricky measurements to get a good number.... although 14.5 and 20 look like different numbers, they no doubt look pretty close when you go to measure a small gear tooth.... I'm not sure I have adequate measuring "stuff" to even try it. And don't even ask me to do that with a 48DP gear....

                              Interesting question though.... you mean it as a joke, but I suppose it is do-able.. You'd have to find the pitch diameter, and determine what the tangent line to the tooth is at that diameter (pitch line), and then compare that to a radius... getting the angle between.

                              I think I'll stick to reading the nice number off the cutter, thank you very much!
                              1601

                              Keep eye on ball.
                              Hashim Khan

                              Comment

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