Specifying sharp threads on drawing
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  1. #1
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    Default Specifying sharp threads on drawing

    So I am considering the possibility of having an evenly spaced round blade made, so if it dulls we can rotate it a few degrees. I was thinking our machine shop might be able to just turn a threaded rod on their lathe at the required TPI, and we could mount the threaded rod on an angle to cut what we need. Is there a good way to specify on the drawing that we need the threads to be as sharp as possible? Thanks!

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    I think you would be best off speaking directly to your machine shop and explaining what you want. From the outside with little information I'm curious what you are cutting and if you would need to make your "thread" out of something hard enough that grinding would make more since.

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    This made sense to me:

    sharp-threads.jpg

    Regards.

    Mike

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    Quote Originally Posted by AHUNT View Post
    I was thinking our machine shop might be able to just turn a threaded rod on their lathe at the required TPI, and we could mount the threaded rod on an angle to cut what we need.
    The threaded rod will act like an auger if it will be spinning and not do what you want it to do.

    Instead specify a series of grooves with sharp tips.

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    Quote Originally Posted by Philabuster View Post
    The threaded rod will act like an auger if it will be spinning and not do what you want it to do.

    Instead specify a series of grooves with sharp tips.
    If he angles it right wouldn't it cut straight, like a hob?

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    Are you trying to make a forming tool or a cutting tool?

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    We were going to lock the rotation of it. We would want to be able to unlock it rotate it a few degrees and relock it.

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    Quote Originally Posted by CarbideBob View Post
    Are you trying to make a forming tool or a cutting tool?
    We are making a cutting tool.

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    Quote Originally Posted by AHUNT View Post
    We are making a cutting tool.
    With that I'm confused as to where the chip formation and shear occurs.
    I get it as metal spinning or forming tool. I don't get the cutting action.
    I'm missing something as to how this works. Is it sort of used like a broach?
    Bob

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    I'm imagining it slicing like a knife, like when you try to turn a piece of brass all-thread by hand and get a line of cuts instead .

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    Quote Originally Posted by Cole2534 View Post
    If he angles it right wouldn't it cut straight, like a hob?
    Due to the helix angle ;- Not unless whatever he's cutting (like a gear) rotates in sync, with the cutter

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    He wants to rotate it a few degrees when dull for a new edge.

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    Are you cutting, paper, card, foil, plastic sheet, leather or what?

    How many TPI?
    How long is the threaded bar?
    What diameter?
    Does it have to be Sliver Steel/ Drill Rod so it can be hardened?
    Is depth of cut normal thread depth?
    How is the material being cut moved across the threads?
    Thickness of material being cut?

    Trying to visualise just what is happening.

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