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Tip on my first time knurling with a push-type tool?

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  • Tip on my first time knurling with a push-type tool?

    A knurling and turning tool came with my new QCTP, and I decided to give that a shot. Non-centering, but that wasn't tough, but it just didn't give me a good finish.

    The parts I make needed to be 1.125" diameter, my old method was to turn to 1.11, and using the scissor-type knurling tool would bring it to within a few thou, which is fine.

    The press-type tool 1) didn't create a sharp texture, it had flat crowns and then seemed to skip on one of the wheels, appearing to try to make one side medium and the other fine, and 2) seemed to press the texture in completely, instead of pressing halfway in and raising halfway out.

    I'll concede that the knurls on the press-type seem a little rough at the edges, instead of chamfered like the scissor-type, and this time I did have to set the workpiece in the steady rest, which I'm afraid may have let it move more than the way I usually get to work right up against the chuck.

    So... am I missing something, did the piece flex too much, or are these tools a problem on benchtop-sized lathes?

  • #2
    "these tools a problem on benchtop-sized lathes"

    If you manage to use enough pressure you nearly spin your toolpost around, And its generaly considered just bad on the lathe compound/cross slide to be using that much force as its not really designed to support a very large outward force. Keep using the sissor tool, Put the push knurl tool away where it won't cause any harm

    Technicaly, the push knurl can be used on softer metals like aluminum with some success.. But generaly the sissor knurl is considered wayy better, even if it does have a limited diamiter range.
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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    • #3
      Well, I was using it on aluminum...

      Alright, then. I either need to modify this one or buy a new one that can use replaceable knurls. And I guess I could use the mounts on the current tool to make a scissor-type with this one, instead of the flimsy self-centering device on the old one.

      Durnit, now I have another project.

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      • #4
        Perhaps the knurl wheels are defective as you described them. Knurling aluminum should have been a piece of cake even with a push type knurler.
        It's only ink and paper

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        • #5
          If the QCTP is an import, the knurls are worthless. Get a good set of knurls and try again if you are committed to using it.
          Jim H.

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          • #6
            Ahh. Well, then.

            My plan is to buy a couple other pairs of wheels, anyway, I'll give them a shot. If it still doesn't work right, I'll just convert the scissor type to take them.

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            • #7
              Originally posted by JCHannum
              If the QCTP is an import, the knurls are worthless. Get a good set of knurls and try again if you are committed to using it.
              I've had similar problems. What's a "good set of knurls"? I'm not sure how I'd tell aside from rolling the dice while hoping "you get what you pay for."
              ----
              Proud machining permanoob since September 2010

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              • #8
                Stick with known name brands, Dorian, Accu-Trac and Reed to name a few. made in USA or good quality european imports would be next in line. Expect to pay $15-$20 each for good knurls.
                Jim H.

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                • #9
                  I bought the import QCTP , and had the same problems as you have. I got mine from the local Busy-bee outlet thats 5-mins from my house. I went over and got another one, and even though it looked all the same, the results where completly different.

                  If your machine is a mini lathe, I would not use the push type kurler. I would be worryed about the stress it puts on the bearings. If you just bought this, return it. Hell it should work on aluminum.
                  Paul

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                  • #10
                    I'm having the same problem as the OP. Only, I know my knurls are good because I have knurled a few pieces of stressproof with them. The last three things I've tried have ended up with really fine grooves instead of the nice sharp diamond pattern. I'm using course knurls....

                    It's like I'm missing something real basic like feed speed or RPM. Something I may have gotten right by accident on the first few tries. Any idea's?

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                    • #11
                      I think I've figured it out. I knew it was something basic. My last few parts have been oddball diameters. Didn't match up with the knurls. Gonna go try it again....

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                      • #12
                        Boostinjdm,

                        I can see why you refer to 'oddball diameters' - you're thinking that a knurl cuts what's effectively a many toothed helical gear pattern on the work, and hence, to have whole numbers of 'teeth', you need to start with set diameters.

                        In reality, the diameter doesn't matter - I've knurled a tapered shaft before now, which has an infinite range of diameters from end to end - no problems, the whole thing knurled nicely.

                        The problem lies elsewhere...

                        Ian
                        All of the gear, no idea...

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                        • #13
                          This is how I do knurls. This works every time regardless of diameters.

                          My knurling tool



                          Touch on to the work like this and zero the dial.



                          Start up and fed in until a good pattern is achieved.



                          Read the dial. This is 1.8mm. Now we know where we are going. Notice the dodgy knurling on the dial!

                          "...do you not think you have enough machines?"

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                          • #14
                            Approach the knurling as screwcutting, lets say 5 passes to arrive at the final depth. First pass, withdraw and reposition for the next pass..you know the drill.
                            The knurls are registered each pass by the prestarted band.

                            After first pass



                            Completed.



                            Mystery steel 1" dia, speed maybe 300rpm and feed whatever you cut at, coolant, if you have the luxury or oil.
                            "...do you not think you have enough machines?"

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                            • #15
                              David's photos quite clearly show why the the part diameter is a non-issue. The finished knurl is larger than the workpiece.

                              Bump knurling forms the material, and displaces it, creating the final diameter in the proper "pitch". Cut knurling does just the opposite, removing the material necessary to form the proper pattern. In either case, the key is to feed the knurls in until a proper pattern is formed to determine the depth of infeed.
                              Jim H.

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