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Ideas fixturing flanged hubless timing pulley in lathe

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  • Ideas fixturing flanged hubless timing pulley in lathe

    Could use a few ideas how to fixture a small (around 1 inch diameter) flanged and hubless timing pulley in the lathe for boring. Flanges are rather fragile and there is no hub to clamp down on. I've scratched my bald head for a while on this one, and figure there will be a good idea from those more experienced.

  • #2
    Does it have a hole which would allow you to turn a mandrel and push fit the pulley? Or if it face mounts onto the end of a cam with screws then turn a slug to match the end of the cam?

    Otherwise I'd say that a picture of your pulley is worth at least 1000 words and would avoid a bucket load of misunderstanding.
    Chilliwack BC, Canada


    • #3
      This sounds like a case for one of those low-melting-point compounds like cerrobend.


      • #4
        Generally would use a collet to hold very small flanged pulleys (up to 1.75" DIA) You could use soft jaws in a 3 jaw chuck or make your own collet with a slug of ally bored to your diameter, deep enough to take both flanges, then put a single slit in it with a saw and remount in the chuck as it was oriented previously.

        Watch the flange rims are concentric with the pulley rim surface, they aren't always.
        West Sussex UK


        • #5
          Cut out some pieces of aluminum beer can to wrap around your chuck jaws to cushion the pulley.


          • #6
            if you install a section of used timing belt around the diameter of the engagement cogs does it stick out further than the flange?


            • #7
              Bore and turn a piece of aluminum (or whatever you have) into a ring with ID that matches the OD of the belt surface of the pulley. Cut it in half with a saw. Deburr it. Mount in adapter you just made and bore. Done.


              Mount your face plate. Center pulley on face plate with a center in the tail stock. Clamp pulley in place with whatever clamps are necessary. Back off tail stock and bore. Done.
              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.


              • #8
                Make 3 or 4 pins the right length to fit between flanges. Bigger than the groove is fine, you need it to go past the flange.
                Then Chuck in a good 3 jaw or 4 jaw ..depends on tooth number.


                • #9
                  Assuming that you have a 4 jaw chuck there are a couple of possibilities.

                  1) As metalmagpie says and use some Cerrobend and cast it in a mold. When done place the part with the Cerrobend in some near to boiling water and the Cerrobend will melt off the pulley. I have bought Cerrobend on Amazon Prime.

                  2) Two equal length and width pieces of material. The thickness equal or just under the distance between the flanges. Sandwich a piece of thin material between the two blocks and center in the lathe. The center aligned to the shim/thin material. Bore to match the pulley diameter and remove from lathe. Discard the shim and replace with the pulley. Use the four jaws to center the existing bore and then bore to desired diameter.

                  3) Put your location in case one of is your neighbor.

                  Have fun


                  • #10
                    If it is a standard pulley for a timing belt, those flanges are usually just stamped sheet metal and pressed on to the pulley. They can be removed and then reinstalled. You could then just chuck up on the tooth section.


                    • #11
                      Have you got a faceplate. I've fixtured a very wide variety of oddly shaped work to this often overlooked option.
                      Home, down in the valley behind the Red Angus
                      Bad Decisions Make Good Stories​

                      Location: British Columbia


                      • #12
                        If you have soft-jaws just make room for the flanges and grip on the main pulley. Only takes a minute or two.


                        • #13
                          I've used dowel pins before to chuck pulleys and gears. That way I was grabbing on the pitch diameter, not the OD.

                          Sent from my LGLS775 using Tapatalk


                          • #14
                            Exactly, center the bore on the teeth m not the pressed on, stamped flanges. .
                            Unless you want intentional runout, or want to chance it not running true.

                            If part ofvthe pins stick out from the chucks you can then check with a dial indicator.
                            Last edited by 754; 12-16-2017, 01:16 PM.


                            • #15
                              I searched for flanged hubless timing pulley and don't see any that don't have a center hole for mounting on a shaft. That makes a mandrel the obvious choice for most uses.

                              However... It all depends on which surface you are going to work on. Facing will use one fixture, boring will use another, truing up the teeth (working surface) yet another.

                              At the end of the project, there is a profound difference between spare parts and left over parts.

                              Location: SF East Bay.