1. #1
    Dear Forum.

    I'm getting warm on the idea on getting a 4.th Axis for my diy machine.
    Primarily wood routing.

    I found this kit on eBay:
    http://www.ebay.co.uk/itm/CNC-Router...:X:RTQ:GB:1123

    However the motor fitted is a 2-phase stepper NEMA23.

    My machine is build up using 3-phase steppers NEMA23, and I already have the drive and motor in spare.
    So I wanted to replace the motor on the harmonic drive.
    Don't know much about alignment and harmonic drives, but from the picture "it seems" fairly easy.
    Is there any alignment/adjustment involved in this, just so I don't start out breaking the wave generator or flexible gear.?

    1. Alternative could be getting a 2-phase driver, but that adds to price, as I already have motor and driver.
    2. Alternative Getting a belt driven instead, but I like the high torque from this, If one day I would expand with a 5.axis.

    Best Regards, Bo Andersen.

  2. #2
    I have done a similar thing ie:- changed a 2ph motor for a 5ph motor.

    Motor needs to be accurately centered, are the spigot dia's the same, are the shaft dia's the same. I did enlarge the bore of a wave generator, needs to be accurately centered and absolutely free of swarf, dirt.

    The wave generator is usually only held on with grub screw, before you remove it measure the distance from the flange of the motor and make a note of it, this controls the depth of engagement into the flexspline.

    When reassembling it is very easy to engage the generator one tooth out (eccentrically) because of the very fine pitch, make sure it turns nice and freely before tightening the bolts.

  3. #3
    Quote Originally Posted by johnsattuk View Post
    I have done a similar thing ie:- changed a 2ph motor for a 5ph motor.

    Motor needs to be accurately centered, are the spigot dia's the same, are the shaft dia's the same. I did enlarge the bore of a wave generator, needs to be accurately centered and absolutely free of swarf, dirt.

    The wave generator is usually only held on with grub screw, before you remove it measure the distance from the flange of the motor and make a note of it, this controls the depth of engagement into the flexspline.

    When reassembling it is very easy to engage the generator one tooth out (eccentrically) because of the very fine pitch, make sure it turns nice and freely before tightening the bolts.
    Thanks for the heads up on the details.
    Both motors are NEMA23, with 8mm Shaft. So I would assume it's a match.
    Did contact the eBay seller, and they (of course) say the warranty will be void if I open up the gear. Never the less, the freight cost to China is so darn expensive that
    I never would return it anyway.
    Best Regards, Bo Andersen.

  4. #4
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  5. #5
    Search for the harmonic drive datasheets and you'll find notes about assembling them properly.


    Quote Originally Posted by EddyCurrent View Post
    No, it's a lot worse due to the lack of harmonic drive.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  6. #6
    Buy two and make one of these; https://www.youtube.com/watch?v=_aLqeVJC7Ak
    Last edited by EddyCurrent; 23-12-2014 at 12:29 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

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