M3.5 thread with 1mm pitch, very non standard

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M3.5 thread with 1mm pitch, very non standard

Home Forums General Questions M3.5 thread with 1mm pitch, very non standard

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  • #652142
    Ian P
    Participant
      @ianp

      The picture is a Nickel-Silver stanchion-like component that supports the keywork on a woodwind instrument. It has a thread that measures 3.4mm diameter over the crests and as far as I can tell, the 3.5mm length has the same pitch and thread profile as an M6 bolt. The spherical part is 4.8mm diameter.

      sam_0068.jpg

      After extensive searching I have come to the conclusion that it is impossible to buy a ready made tap so I'm wondering whether anyone thinks its feasible to make one? It is not something that will ever be heavily used and its not tapping into hardened steel although African Blackwood is probably not far off!

      Ian P

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      #29282
      Ian P
      Participant
        @ianp

        How to thread a hole in (VERY) hard wood

        #652175
        speelwerk
        Participant
          @speelwerk

          Perhaps possible to find a wood screw with similar thread and use that as tap. Niko.

          #652179
          Huub
          Participant
            @huub

            For wood, I use (and make) roll taps. That works better than my taps for steel.

            Just make a M3.5 x 1 thread on a peace of hex steel and use that to tap the hole in wood.

            Drill diameter should be the same as for a M3.5 x1 metal tap 2.53 mm (2.5)

            Crest diameter for the tap should be 3.5 mm

            Cutting depth for a sharp, self grind threading tool should be 0.704 mm

            Cutting depth for an insert 60°, for 0.5 mm pitch should be 0.65

             

             

            Edited By Huub on 13/07/2023 23:12:15

            #652180
            Emgee
            Participant
              @emgee

              Hi Ian

              Some time ago I made a tap from silver steel and hardened it for use in wood, it had 45 degree flanks so thread form was 90 degrees, the person it was made for reported it worked OK.
              The part in your pic seems to have rounded crests, can you measure accurately crest to crest to confirm the pitch is 1mm ?

              What is the minor diameter ?

              Emgee

              #652184
              bernard towers
              Participant
                @bernardtowers37738

                Depending on how old and where manufactured it could be a No6 American thread

                Edited By bernard towers on 13/07/2023 23:23:28

                #652233
                Ian P
                Participant
                  @ianp

                  The part is almost certainly metric, made in France and is 1mm pitch (USA No 6 is 32tpi).

                  A roll tap would make sense but the wood used for oboes is so hard and dense its virtually incompressable that I think a tap would have to cut most of the thread form. The hole is blind and only 4mm deep so I think I will need to do lots of experimenting

                  Ian P

                  #652235
                  ega
                  Participant
                    @ega

                    The grain direction of the wood will probably be a consideration.

                    #652249
                    Huub
                    Participant
                      @huub
                      Posted by Ian P on 14/07/2023 10:44:06:

                      A roll tap would make sense but the wood used for oboes is so hard and dense its virtually incompressable that I think a tap would have to cut most of the thread form. The hole is blind and only 4mm deep so I think I will need to do lots of experimenting

                      Using a roll tap M3.5 x 1 for steel requires a drilled hole of 3 mm.

                      Making/turning a tap isn't that difficult but takes some time. This video shows how I make a tap from round steel Turning a tap. It is easier if you use hex steel.
                      For a roll tap, I use the same procedure but without milling the flutes. For wood, I use mild steel without hardening.

                      #652256
                      SillyOldDuffer
                      Moderator
                        @sillyoldduffer

                        Taps aren't difficult to make. Don't last as long or cut as well as commercial taps, but OK for specials.

                        First cut the required thread pitch in a rod. Silver Steel is best because it can be hardened and holds an edge, but mild-steel copes with softer materials for a short while.

                        Then cut 4 slots along the thread to create teeth: I normally mill them, but a file works too. Finish, by filing off the flank, non-cutting, side of the teeth to provide relief. Not shown in the CAD pic, but the rod should be chamfered to lead the teeth into the hole.

                        homemadetap.jpg

                        That's a basic tap. Can be improved, for example by cutting the thread into a mildly tapered rod. As this type of tap doesn't cut brilliantly, it might pay to make three with gradually deepening threads. (A first, second and third set.)

                        I guess the main difficulty is the job will be a bit fiddly and delicate, at least by my clumsy standards. M3.5 x 1.0 is a relatively coarse pitch for a small diameter rod.

                        Dave

                        #652279
                        David George 1
                        Participant
                          @davidgeorge1

                          Hi Ian I have made special taps mainly for cutting metal parts but the same could be done for your wooden part.

                          20190518_093401.jpg

                          20190519_091437.jpg

                          I screw cut the thread on a piece of silver steel , then using a ball nosed cutter cut the cutting edge. It was then flame hardened. 20191012_115556.jpg

                          These were similar items I made for a friend but made from bronze for an unknown musical instrument.

                          David

                          #652291
                          Emgee
                          Participant
                            @emgee

                            Time flies, I made the tap in 2015 which I mentioned in my last reply, video link below shows the turning, milling, hardening and flute finish grinding process.
                            **LINK**

                            Emgee

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