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  1. #101
    Quote Originally Posted by irving2008 View Post
    Not as far as i am aware... just signed up, threw an order of about 30 at them, job done...
    I think that's only if you don't order below 20 the first time.

    Certainly they used to have an MOP of 20 (which meant I always over-ordered on items), but now they don't for me.

  2. Quote Originally Posted by tribbles View Post
    I think that's only if you don't order below 20 the first time.

    Certainly they used to have an MOP of 20 (which meant I always over-ordered on items), but now they don't for me.
    No, its because i used a debit card, the 20 MOP applies to credit cards only.

  3. #103
    Ok In case your thinking this tread is getting a bit stale I'd better post some pic's. Again apologies for the quality, need a new camera really.

    The motor mounts are finished as is the MK3 anti-backlash nut for the X axis. Its all a bit messy as Ive had to use alu angle and modify bits from the original machine. some bits are still mock up and I may remake them if I get time.

    Thanks to John S for the idea for anti backlash solution. I had to change it slightly as the first incarnation of just sandwiching the orignal nut with delrin kept twisting slightly and producing more BL. This design uses the first to plates to sandwich to original nut, and prove a fixed base, whilst the delrin is fixed to the end plate, the spring in between means that i can back of the tension on the adjusters as well. Having played around with this there seems to be a very fine line between zero BL and too much friction. Comments and abuse welcome :heehee:
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  4. #104
    Quote Originally Posted by Ross77 View Post
    there seems to be a very fine line between zero BL and too much friction.

    Why have you got nuts behind the stator plate? If you tighten them the spring does nothing and the line will be fine

  5. #105
    Why have you got nuts behind the stator plate?
    Hi Robin
    Not sure what you mean by a stator plate? in the 2nd picture the left hand and middle plate are clamping the original nut, tightened by the middle nuts (to resist rotation). the delrin nut is fixed to the right hand plate and is adjusted by the end nuts to compress both drive nuts to reduce backlash.

    The spring is purley overkill and just pushes the delrin nut on to the adjuster nuts and also ensures that if I back of the adjuster nuts then the delrin nut moves with them to give positive control over the pre-tension.

    Ive tried 3 or 4 different versions and this set up worked the best, is the easiest to align and easiest to adjust.

    I presumed that there is always a fine line between eliminating backlash and excessive friction?

  6. #106
    Made some good progress this weekend.

    Gave up honing the ways as they were so far out of true and had to scrape them. I used a 60 deg. Carbide tipped lathe bit (held in a 3-4 MT adapter :whistling:)

    I can see why people dont like doing it, very time consuming, repetative and hard work.

    So with the ways sorted, motor mounts done and the antibacklash nuts finnished I decided to give it a lick of paint. :dance:
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  7. #107
    Amazing Ross, coming along nice mate !

    What paint did you go with in the blue ?
    .Me

  8. #108
    Thanks Lee. Hope to get it assembled soon....Other projects and uni looming...........................

    Can't remember the makers name but its supposed to be a hardwearing hammered finnish same as Hammerite. The casting was so so rough I thought a flat paint would look terrible.

    This should be a good test for the paint. If it can resist way oil, coolant, grease and all the other nasties that will be thown at it.

  9. #109
    After 2 months I've been able to fit in some workshop time

    So the z axis is done and I've managed to hot-wire the controller board to work with step and direction so "IT WORKS" just need to find a better way to transfer the IC to another board.

    Tested the x axis and there is no backlash, using a 0.001" gauge it always returned to the same place

    The breadboard circuit is the stepper exerciser that Irvine designed for me. Thanks again it works great, no need the drag the pc out.

    Now for the question........
    Should steppers hum/crackle whilst holding? it only seems to happen on certain motor positions. It also gets worse/louder when I turn up the Vref to increase max current.

    It also seems to buzz/miss steps at about 300 rpm, is that normal?

    Thanks in advance.
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  10. #110
    Quote Originally Posted by Ross77 View Post
    Should steppers hum/crackle whilst holding? it only seems to happen on certain motor positions. It also gets worse/louder when I turn up the Vref to increase max current.

    It also seems to buzz/miss steps at about 300 rpm, is that normal?

    Steppers usually make their best noises when in action, on hold the current is usually cut because you don't need the pulling power.

    300rpm is not bad for a stepper, but it isn't good either :nope:

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