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Straight Knurl on a tapered extrusion

By John DiPietro on 10 Jun 20:21 3 answers 2 comments

I'm trying to create a straight knurl on a tapered extrusion. Similar to a tapered plastic knurled knob for a jackscrew. I can't follow a cut from top to bottom. Should I be using a different command?

3 answers

  • Shane Anderson
    Shane Anderson over 4 years ago

    Firstly what do you mean by Straight Knurl?
    i make knurled features by rolling the material in a knurling tool. i only ever knurl cylindrical things, not tapered things.

    If i wanted to make a part by cnc or injection - not actual rolling i would model the knurl into the part and then have a nice grippy knob. but that's enought chatter about my knob - lets talk about your's!

    knowing the dimensions of the tapered cylinder (angle of 1.6 deg and length of .65") make a circle sketc on the end of your knob. either end will do. make the circle the same diameter as the end of the knob the sketch is placed on.

    then make a helix with that circle that tapers in the same direction and amount as the knob.

    make a helix that is defined by revolutions and height (not pitch and etc.)

    draw a plane on the end of the helix normal to the helix. or if you are cheap on the same face as the circle.

    draw a knurl groove detail touching the helix.
    sweep-cut the groove profile along the helix.
    pattern the sweep-cut with a circular pattern (polar array).
    then mirror the array to get the complimentary groove set that makes the diamond shape.
    adjust the pattern instances and the helix twist for the proper results.

    the model attached doesn't use a proper groove nor are the grooves at the proper angel but you get the idea!

    best of luck.

    Attachments

    taper_knurl.STEP, 20.6 MB
    Download
  • Shane Anderson
    Shane Anderson over 4 years ago

    cut using the sweep command. make a guide curve to follow the taper. show us a picture of your part. if the knurled part is moulded no problem but is it machined/formed? i can't imagine using a knurling tool on a tapered part.

  • John DiPietro
    John DiPietro over 4 years ago

    Thanks, but I'm still a bit confused. The knob is going to be molded on to a screw barrel. I'll need to add a straight knurl on the attached. Any help will be appreciated.

    Attachments

    taper.ipt, 79.5 KB
    Download
    taper.stp, 5.05 KB
    Download

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