Gear cutter number standardisation
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  1. #1
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    Default Gear cutter number standardisation

    Range of Cutters for Involute gear cutters Cutter Number Cuts Gear from
    1 135 teeth to rack
    2 55-134
    3 35-54
    4 26-34
    5 21-25
    6 17-20
    7 14-16
    8 12-13

    The above seems to be the western standard, but Chinese cutters seem opposite to me, which makes me wonder about their standards. I bought a number 2 cutter to make a 127 tooth gear but when I asked the Chinese seller if it was correct for that he said no, that I needed a number 7.
    I ended up buying three cutters from Victor machine traders company, a #2, #3 and a #4, and have no idea where the cutters were made, but OTH I'm having to pay two or three times as much as I would have buying direct from the Chinese.
    American gear manufacturers apparently decided some time ago that 14 DP and 18 DP would no longer be offered, nor cutters either through standard tool distributors.
    So, have other guys seen what I think I've seen, that Chinese cutter numbering is backwards?
    Thanks,
    parts

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  3. #2
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    Yes I have bought a chinese cutter but realised before I bought it that their numbering system is arse about face.

    It had me confused at the start as well...

  4. #3
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    Seems like US standard is once again reverse from rest of the world (no offence here, just wondering..)

    In module pitch (which is probably the most used standard in the world) smaller the cutter #, the fever teeth count it is for.

    Checked some of my cutters and they are numbered like this:
    These are mostly old German, Japanese and Finnish made quality tools, none of them are chinese.

    #1 12-13T
    #2 14-16T
    #3 17-20T
    #4 21-25T
    #5 26-34T
    #6 35-54T
    #7 55-134T
    #8 135-Rack T

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  6. #4
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    I got the impression English standards are the same as ours. Maybe it relates to Inch or "Imperial" measurement? I can see how that might have confused the Chinese.

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    You can also find cutters labelled #0 to #7 and you can often find them in half sizes (usually for larger sizes)

    e.g.
    #1 - 135 to rack
    #1.5 - 80 to 134
    #2 - 55 to 79
    #2.5 - 42 to 54
    #3 - 35 to 41
    #3.5 - 30 to 34
    #4 - 26 to 29
    #4.5 - 23 to 25
    #5 - 21 to 23
    #5.5 - 19, 20
    #6 - 17, 18
    #6.5 - 15, 16
    #7 - 14, 15
    #7.5 - 13
    #8 - 12

  8. #6
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    There is a formula used in cutting helical gears on a spiral milling setup. I don't have it handy but it had to do with which cutter you chose when milling because of the way the cutter cuts a groove slightly wider than itself. The formula involved the cube of the cosine of the helix angle, and the result when rounded off told you which cutter number to choose. So the cutter numbers aren't just numbers!

    It occurred to me that the numbering system might be inverted for module since diametral pitch is kind of inverted compared to module.

  9. #7
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    I hadn't noticed that, but it is good to know. I will be on the lookout whenever I buy gear cutters.

  10. #8
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    I have a selection of British DP cutters, they follow the OP's standard of the smaller the number closer it is to a rack.

    Steve


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