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Keyway done -- finally!!

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  • #16
    Originally posted by Ken_Shea
    If it is not a lot of trouble for you that information could save some time, I am unable to find the pulleys needed for my project and that just may be a solution. I am not looking for perfection only to get it progressing as it has been on hold because of the timing pulleys being unavailable. There's a million things yet to do but with out these pulleys it matters little.

    With the HTD5, 5.0mm. pitch, Pitch Diameter (PD) is NoTeeth x .1969" / Pi.

    The pitch line of the belt will fall closer to the middle of its thickness so:
    Pulley OD = PD - .045" (This is verified in catalog pulley dimensions)

    The hole circle for the belt teeth = PD - .076"

    I believe the teeth on the belt are 3.0mm so a 1/8" or #31 drill would provide some slight clearance for the teeth.

    Probably self-evident, but turn the blanks a large enough diameter to drill through solid material, then turn the OD down to size. I used the material for flanges, which may or may not be necessary.

    And, since the centerline of the holes falls below the OD, the peaks left after turning down to the holes should have the corners broken (ideally a small radius) so it doesn't chew into the inside corners of the belt. My plan was to make a small scraper form tool and harden it to get the corners.

    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill