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How to cut buttress threads?

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  • #31
    Making parts .

    Originally posted by oldtiffie
    You've got it Ian.

    Eating an elephant can seem a daunting task - if you want to do it in one go - but its a lot easier with lots/more chewable and digestible bites.

    I'd have done the roughing using what are essentially "parting tools" and the cross-slide for the straight plunge in (as for square threads) and then the top-slide set at 45* for the 45* flank.

    The rest is just a clean-up - taken slowly.

    The cuts are making a spiral not a groove and with that size helix angle I'd be tilting the screwing tool/s.

    I don't know how the Law applies in the OP's state or country, but here in OZ car hoists (as in commercial garages etc.) come under the "Cranes, Hoists and Lifting Gear Code" and all components parts or assemblies must be designed, made to and Inspected in accordance with the Code.

    The Code also covers and requires testing for replacements if required.

    The hoist is required to be checked by an Inspector and load-tested at set intervals.

    If the hoist fails a test or is overdue it is regarded as being "out of test" and is not to be used until it is "passed".

    There is no way I'd make that nut here.

    The hoist has clearly had a substantial failure and must only be repaired and probably tested and Inspected in accordance with the Code.

    I don't think I'd like to be served with a writ or a warrant if anyone got hurt or worse.
    It is possible to make parts as long as you make them using material which is the same or higher quality as original .
    The testing can be completed by a "competent Person"
    A lot of us exist in the maintenance field , if you work in these areas there is no scrimping on material or tolerances .
    I also make replacement parts for final drives in machinery at times , it is not an area to be taken lightly ,however even original manufacturer supplied componemts can and do fail with often serious consequences.
    If you always follow the original specs and use the correct material , you will find that there isnt a problem, unless you create it .