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  1. #161
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    Quote Originally Posted by implmex View Post
    Oh yeah...while I'm at it: resist the urge to try to make this work like a Maag gear grinder.
    That's how I would do it tho I mean, he's got the linear in Z and the rotary in B, why not ? It's no harder than the animations that David M has been making. In fact, it's the same. Borrow that algorithm

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    Hi EmanuelGoldstein:
    My reasons for arguing against the Maag gear grinding process for this OP and this adaptation of it are twofold.
    First, it adds some complexity to the programming that I would not personally spend the time on because I'm not sure it would make a significantly better gear or make it much faster.

    The second and more important one is the fact that a Maag uses angled, flat faced, relatively large grinding wheels whereas the Speedio will need to use a relatively small cutter whose angled faces are cones.
    My expectation is that the traverse rate across the face of the gear would have to be very slow to avoid significantly scalloping the tooth faces and flanks when milling while rocking the gear, whereas the grinding wheels makes any potential scallops virtually undetectable since the wheels are so big and flat.
    Of course, making a bunch of linear passes with a rack shaped cutter means that the involute profile that's developed is a bunch of tiny flats. but that can be mitigated by making lots of passes with small angular increments of rotation, and if it's good enough for Sunderlands and Maag shapers it should be good enough for us all.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

  3. #163
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    Quote Originally Posted by implmex View Post
    The second and more important one is the fact that a Maag uses angled, flat faced, relatively large grinding wheels whereas the Speedio will need to use a relatively small cutter whose angled faces are cones.
    Hobbing makes scallops, too. The arcs are the diameter of the hob, so as long as your cutter is larger than a hob (usually about 3 or 4 inches) then you will get an equal or better surface than hobbing.

    Also, on the smaller Maags, the more normal method of grinding is called "zero degree" - your video shows the wheels angled at 20* using the larger flat surface, but in really accurate stuff it's more common to use the other edge, with a really small contact area.

    Pratt & Whitneys were interesting, they used huge (20" or 22") wheels and didn't bother traversing at all, just ignored the (minute) amount of curvature. Sometimes you can see that on some Fellows shaper cutters by looking in the roots for an arc.

    My expectation is that the traverse rate across the face of the gear would have to be very slow to avoid significantly scalloping the tooth faces and flanks when milling while rocking the gear, whereas the grinding wheels makes any potential scallops virtually undetectable since the wheels are so big and flat.
    Look at a hobbed part. They are all scalloped The feedrate determines the width of the scallops. If you look in the root it is more obvious, a helix running around the part at the feedrate of the hob through the blank.

    Of course, making a bunch of linear passes with a rack shaped cutter means that the involute profile that's developed is a bunch of tiny flats.
    Except for form grinding and shaving, all tooth cutting methods leave a succession of tiny flats

    (Or tiny arcs in some cases, but same deal)

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    Hi again EmanuelGoldstein:
    I just want to take a moment to thank you for your participation in this thread.
    I got a huge amount of super good knowledge and experience from you, and I really appreciate it.
    Thank you Sir!

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining
    Last edited by implmex; 06-23-2019 at 12:39 AM.

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  6. #165
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    Quote Originally Posted by implmex View Post
    Hi again EmanuelGoldstein:
    I just want to take a moment to thank you for your participation in this thread.
    I got a huge mount of super good knowledge and experience from you, and I really appreciate it.
    Thank you Sir!

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining
    I agree with Marcus, it is much appreciated!

    Best regards,

    David

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    Quote Originally Posted by implmex View Post
    Hi again EmanuelGoldstein:
    I just want to take a moment to thank you for your participation in this thread.
    I got a huge mount of super good knowledge and experience from you, and I really appreciate it.
    Thank you Sir!

    Cheers

    Marcus
    I second this, thank you EmanuelGoldstein.

    Also thank you Zahnrad Kopf.

    Also, big thanks to motion guru as well.

    This thread has been tremendously valuable.
    The expertise on this forum is phenomenal.


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