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    Brushless motor couling
    by stevecw ๐Ÿ‡ฌ๐Ÿ‡ง ( Able Seaman)
    ๐Ÿ“ฃ










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    15 Posts 14 Replies 5 Photos 12 Likes
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    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 days ago
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    Steve,
    An alternative to sawing off the threaded part of the shaft at the coupling end.
    Buy the spiral coupling with a 3mm I/D at the output end.
    Drill it out with a 4mm tap drill, = 3.4mm and tap a 4mm thread 0.75 (normal) or 0.76 pitch to match your shaft end. (๐Ÿ™„)
    Bingo. Bob's yer Uncle and Fanny's yer Aunt. Job done๐Ÿ‘๐Ÿ˜Š
    Cheers, Doug ๐Ÿ˜Ž
    https://www.boltdepot.com/fastener-information/metric-tap-dr...
    https://www.boltdepot.com/fastener-information/metric-tap-drill-size.aspx
    ๐Ÿ”—
    Young at heart ๐Ÿ˜‰ Slightly older in other places.๐Ÿ˜Š Cheers Doug
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 days ago
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    Thanks Rowen๐Ÿ‘
    Forgot that older shafts were like that.๐Ÿ˜”
    Since I got my mini lathe and milling machine I've got used to making my own!
    Cheers, Doug๐Ÿ˜Ž
    Young at heart ๐Ÿ˜‰ Slightly older in other places.๐Ÿ˜Š Cheers Doug
    Rowen
    Commander
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡จ๐Ÿ‡ฆ Canada
    Online: 8 hours ago
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    Not unusual. Some shafts fit both screwed propeller and a screwed coupling, thus threaded at both ends.
    If you want to use a coupling with flats and grub screws, just cut the thread off. May have to shorten the outer tube to compensate.
    1
    stevecw
    Able Seaman
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 9 months ago
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    Thanks again. Strangely enough the prop shaft is threaded on both ends. The same thread on each end.

    Cheers.
    RNinMunich
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    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 days ago
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    Hi Steve,
    The inserts of the spiral coupling are not threaded.
    They are secured with grub screws.
    That's why I milled depressions in the shaft to prevent any slippage.
    See my 2nd pic below with the shaft and coupling on the mini milling machine.
    Use a flat ended mill bit to prevent it skidding off the shaft - like spiral drills would๐Ÿ˜ 
    I also fitted a collet in the same way, visible to the right of the pic.
    I then fitted spacer washers between the collet and the end of the shaft tube.
    Prevents the shaft and prop exiting stage backwards if the coupling should come loose.๐Ÿ˜ญ
    Which mine never has ๐Ÿคž๐Ÿคž

    3.94mm I would say is well within the tolerance of a 4mm drawn rod, especially those produced for the model market, and not for a NASA rocket ๐Ÿ˜‰
    I assume that your prop shaft is only threaded at one end.
    That's where you screw the prop on. DON'T forget a lock nut and a thrust washer๐Ÿ‘
    The plain end goes into the coupling. If you can't mill a depression into the shaft for the grub screw just file a flat. Secure the grub screw with Loctite or similar.
    Hope this helps.
    Any doubts just YELL.
    Cheers, Doug ๐Ÿ˜Ž
    PS Just added two pics re milling the prop shaft๐Ÿ‘
    Young at heart ๐Ÿ˜‰ Slightly older in other places.๐Ÿ˜Š Cheers Doug
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 days ago
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    "The centre of the sleeve can as also be filled with grease or oil to maintain lubrication "
    That's a neat idea Rowen๐Ÿ‘
    Could give my old couplings a new lease of life.
    Cheers, Doug ๐Ÿ˜Ž
    Young at heart ๐Ÿ˜‰ Slightly older in other places.๐Ÿ˜Š Cheers Doug
    stevecw
    Able Seaman
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 9 months ago
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    Many thanks gents (I'm assuming gents, sorry if not), all very useful information for the novice!
    Next question if I may - my prop shaft was bought about 20 years ago and when I use my digital calipers the plain bit of the shaft is 3.94mm dia. How do I know what the thread is to order the correct threaded insert for the coupling? Can I somehow convert the number of threads per mm? 13 revolutions of the nut on the prop shaft moves the nut 10mm so i'm assuming that 10/13=0.76 means that it should be an M4. Is this correct?

    Thanks again in anticipation.
    Rowen
    Commander
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡จ๐Ÿ‡ฆ Canada
    Online: 8 hours ago
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    Agree with the clackety clack noise. I slide a length of plastic tube over the coupling once all is lined up.
    This sleeve reduces backlash in the coupling and quietens it down.
    The centre of the sleeve can as also be filled with grease or oil to maintain lubrication
    2
    RNinMunich
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    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 days ago
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    Hi again Joe,
    It was Krick!
    You can order them with a variety of input / output diameters.
    Cheers, Doug ๐Ÿ˜Ž
    https://www.krickshop.de/e-vendo.php?shop=krick_e&SessionId=...
    https://www.krickshop.de/e-vendo.php?shop=krick_e&SessionId=&a=search&SearchStr=searchfield_technic_0%3Astegkupplungen
    ๐Ÿ”—
    2
    Young at heart ๐Ÿ˜‰ Slightly older in other places.๐Ÿ˜Š Cheers Doug
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motor couling
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 days ago
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    Hi Joe,
    I like the spiral coupling a lot. Takes the full power of my 1000kV motor running on a 3S LiPo without a whimper.๐Ÿ˜Š You have to be careful with the initial alignment though as it won't flex as far as UJs. personally I didn't consider that a drawback๐Ÿ˜‰ Being compressible it also absorbs any forward thrust on the shaft๐Ÿ‘
    This was my first BL setup and I had read / heard of them ripping the inserts out of the conventional plastic / brass UJ couplings. Had used those for years on my brushed motors.
    But I learned to avoid the ones made of metal only. Too much clackity clack!
    Sometimes the metal to metal contact seemed to create RF interference๐Ÿค”

    I think my coupling was from Krick, was a few years ago now, I'll check.
    Maybe Cornwall Model Boats can help you with 3/16" stuff?
    https://www.cornwallmodelboats.co.uk/

    My Sea Scout originally had a 3/16" shaft. I swapped it for a 4mm one. The original was worn anyway.
    If all else fails you could always re-thread the old props!?
    Cheers, Doug ๐Ÿ˜Ž
    https://www.cornwallmodelboats.co.uk/
    ๐Ÿ”—
    1
    Young at heart ๐Ÿ˜‰ Slightly older in other places.๐Ÿ˜Š Cheers Doug
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