opinions .125" hole 5" deep into nylon plastic - Page 2
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  1. #21
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    As was said ..
    please indicate some quantities and desires re: specs and costs and speed.

    Making 5 for a space probe is one thing.
    Making 5000 for a mechanical engineering assy is another.

    I wag about 4-6 microns in straightness, tir, and size in thermally controlled plastic of very good type, for == 3 mm // 120 mm deep at the medium-high end for a high cost per hole.

    I also wag that none of critical parameters in size, roundness, straight, finish, or hole end will be good in any plastic at 3 mm / 120 mm, once it is unclamped, or warms, etc.

    My guesstimate would be for "let me try one piece".
    Triple your error or triple your cost - let the customer decide.

    My main effort might be to sell the customer on a better solution.
    A metallic insert or metallic goop, finish machined in situ.

    Another good option might be to explain to customer..
    single-lip bored to size for a final cut of 0.002" will have about 1-2-3 thou of error or less, when mounted.
    But unclamped the piece is likely to have much more error.

    If/when the piece is not stable, how much money do they want to spend on a hole ?
    If the hole must be stable, could an insert not be better ?

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  3. #22
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    Thanks everyone!

    More (maybe less?) information from the customer.
    The part will be molded from top secret material. Some holes need to be added later.
    Being custom material that is molded, no actual size sample will be available to try before the parts are molded.
    The usage is secret. All details are secret.
    NDA required.

    So I will propose that we test a bunch of different plastic with a parabolic drill and see what kind of wandering/tolerance we observe.
    If all the plastic samples look OK , we can proceed to plan to use that parabolic drill when the real parts are molded.
    I suspect this is going to work for the actual tolerance needed.

    We can only guess what actually matches the final plastic material.

    Second backup is to go with the gun drilling.
    Or carbide drill......

    They want quotes for up to hundreds of parts.
    Since I don't know anything about the abrasiveness of the material we will have to make an initial assumption and adjust from there.

    Some times you work with what you got..
    Thanks again.

  4. #23
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    Quote Originally Posted by 3t3d View Post
    More (maybe less?) information from the customer.
    The part will be molded from top secret material. Some holes need to be added later.
    Being custom material that is molded, no actual size sample will be available to try before the parts are molded.
    The usage is secret. All details are secret.
    NDA required.
    Maybe you should tell them that your final hole size, location tolerances, turn around time and part prices are all confidential.

  5. #24
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    They really are a great customer to work with.
    They have constraints on what they do, and I can (usually) work around whatever I have to..


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