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Thread: Machine a Cotter to lock a sliding part to a shaft

  1. #1
    jjr2001's Avatar
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    Machine a Cotter to lock a sliding part to a shaft

    This is a part that will be used in an up coming project but I think this cotter and sliding shaft system
    could be used in many applications in the home shop.

    Cotter may refer to: Cotter pin, a pin or wedge used to fix parts rigidly together.

    I did not invent this but I implemented it a bit different than the example I used to make it from.
    It will lock a part to a shaft and prevent it from rotating or slipping. In my case I am using
    it to lock a rail block to a vertical shaft. It could also be used to make an adjustable sliding table or dolly
    for a photographic rail or a table on a machine tool.

    The cotters are 3/8 diameter brass with 1/4-20 threads on each end of both.
    The holes for them are drilled and reamed first in the block. Then the large 3/4" hole is
    bored and reamed with the cotters installed and fixed with the 1/4-20 nuts and washers.

    After the shaft (3/4") has been lapped to the vertical post the nuts are removed and the
    front end of the cotters have the threaded ends removed. The neat thing here is that with
    one 3/4" hole you are making the 3/8" radius on each of the cotters at the same time.
    I like that, 3 functions done with only one hole drilled!

    The cotters are then lapped for a fine sliding fit. The yoke is installed on the cotters and they
    can now be used to clamp the rail block to the vertical post.


    Cheers, JR
    Attached Thumbnails Attached Thumbnails Machine a Cotter to lock a sliding part to a shaft-img_2384.jpg   Machine a Cotter to lock a sliding part to a shaft-img_2390.jpg   Machine a Cotter to lock a sliding part to a shaft-img_2391.jpg   Machine a Cotter to lock a sliding part to a shaft-img_2392.jpg   Machine a Cotter to lock a sliding part to a shaft-img_2378.jpg  

    Machine a Cotter to lock a sliding part to a shaft-img_2380.jpg   Machine a Cotter to lock a sliding part to a shaft-img_2381.jpg   Machine a Cotter to lock a sliding part to a shaft-img_2383.jpg  

  2. The Following 6 Users Say Thank You to jjr2001 For This Useful Post:

    Jon (02-17-2019), LMMasterMariner (02-18-2019), Metallurg33 (02-19-2019), olderdan (02-17-2019), rossbotics (02-18-2019), Shanty (02-18-2019)

  3. #2
    olderdan's Avatar
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    Way to go JR, I have long been a fan of cotters for those kind of situations, free running non marking and a solid grip.

  4. The Following User Says Thank You to olderdan For This Useful Post:

    jjr2001 (02-18-2019)

  5. #3
    jjr2001's Avatar
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    Thanks Dan, I am getting ready to put that cotter to the test.
    Cheers, JR

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    rossbotics rossbotics's Avatar
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    Good work JR.
    I like those type of locks as well, no maring the shaft, good work

    Doug
    Comments are always welcome
    Doug

    Subscribe to my you tube channel

    https://www.youtube.com/channel/UCDD..._as=subscriber



    Tool Plans for Sale by rossbotics






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    jjr2001 (02-18-2019)

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    jjr2001's Avatar
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    Thanks Doug, I always appreciate your comments. A lot of enjoyment picking up new ideas (to me)
    in my machining quest.

    Cheers, JR

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    Thanks jjr2001! We've added your Shaft Locking Method to our Fastening category,
    as well as to your builder page: jjr2001's Homemade Tools. Your receipt:





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