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  1. #11
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 11 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 8,408. Received thanks 1,440 times, giving thanks to others 108 times. Referred 1 members to the community.
    Quote Originally Posted by JimJam View Post
    is that link you posted somewhere you've bought stuff from before?
    Yes I buy from them all the time. Don't worry about buying from China as they are trustworthy and well proven with many users in UK.

    Also if you buy them thru the Aliexpress link I gave you then your protected by Aliexpress guarantee, they basically don't pay the seller until you have received them and say you are happy. They still charge you upfront but do not pass the money on until you are happy.

    Edit: You will get charged VAT and Admin fee of around 15-20 on top of that price when they enter this country. You don't get charged Import duty.

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  3. #12
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 13 Hours Ago Has been a member for 4-5 years. Has a total post count of 369. Received thanks 47 times, giving thanks to others 7 times.
    CNCdrive sell a step/dir DC servo for brushed motors. I've got 2 of them on my Shizuoka and they have been a great experience. These are about 100 each, which hardly breaks the bank. They also avoid the need to mess about with a perfectly good installation.

    http://shop.cncdrive.com/index.php?productID=366

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  5. #13
    Quote Originally Posted by Muzzer View Post
    CNCdrive sell a step/dir DC servo for brushed motors. I've got 2 of them on my Shizuoka and they have been a great experience. These are about 100 each, which hardly breaks the bank. They also avoid the need to mess about with a perfectly good installation.

    http://shop.cncdrive.com/index.php?productID=366
    oh ok, that does sound like another possible route to take then. So with those drives, I would just need to buy a breakout board to link up to a PC and some control software and I would have a useable machine? providing my motors are still good...

    If I did take this route the current setup uses linear scales for position feedback, would that be easy enough to incorporate into this type of system somehow?

  6. #14
    Quote Originally Posted by JimJam View Post
    oh ok, that does sound like another possible route to take then. So with those drives, I would just need to buy a breakout board to link up to a PC and some control software and I would have a useable machine? providing my motors are still good...

    If I did take this route the current setup uses linear scales for position feedback, would that be easy enough to incorporate into this type of system somehow?
    You will need separate DROs which are not expensive. Can not be integrated on a cheap or middle priced board. This could be done on very expensive boards only like the Galil and such that support double control loops
    project 1 , 2, Dust Shoe ...

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  8. #15
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 13 Hours Ago Has been a member for 4-5 years. Has a total post count of 369. Received thanks 47 times, giving thanks to others 7 times.
    Yes, there's no magic solution to backlash and accuracy. The idea of closing the loop with external DRO scales sounds pretty neat but as Boyan says, it's only very expensive controllers that support that concept. And an expensive system using such a controller probably has very little mechanical nonlinearity and/or backlash to start with.

    If you have a basic system with loads of backlash, no controller in the world will be able to able to make sense of the nonlinear behaviour in a sensible way. Imagine trying to drive a car down a windy road with half a turn of lost movement on the steering wheel, then trying to fix that by adding some form of simple closed loop.

    Your system is either going to be worn out in which case you need to either live with it or fix it - or it's in good shape in which case you should just fit a modern controller and get on with life. Sounds as if it's quite a decent machine to start with. Apart from bragging rights, what accuracy do you think you actually need? 10-20um? That's still 50th - 100th of a mm. I would start by measuring what I have and take it from there.

  9. #16
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 11 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 8,408. Received thanks 1,440 times, giving thanks to others 108 times. Referred 1 members to the community.
    Quote Originally Posted by JimJam View Post
    If I did take this route the current setup uses linear scales for position feedback, would that be easy enough to incorporate into this type of system somehow?
    I've got a feeling Jamie means the machine is using linear scales rather than encoders for position feedback, which the Anilam Crusader II controller would allow. And wants to know if the scales can be used with the CNCdrive.! Am I correct Jamie.? . . . If not the ignore me and listen to the others because it's correct what they say.!

  10. #17
    Quote Originally Posted by JAZZCNC View Post
    I've got a feeling Jamie means the machine is using linear scales rather than encoders for position feedback, which the Anilam Crusader II controller would allow. And wants to know if the scales can be used with the CNCdrive.! Am I correct Jamie.? . . . If not the ignore me and listen to the others because it's correct what they say.!
    Yes exactly as you say, sorry I probably didn't explain that very well. I meant that it is currently using linear scales and wasn't sure how it would give positional feedback to the controller if using the CNCdrive muzzer posted without encoders on the motors..

    Apologies again for not understanding what's probably the real basics for you guys! Appreciate your patience and sharing your knowledge.

  11. #18
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 13 Hours Ago Has been a member for 4-5 years. Has a total post count of 369. Received thanks 47 times, giving thanks to others 7 times.
    You could try connecting the DRO encoders to a DC servo drive but unless you had near-zero backlash, the drive could be almost impossible to tune. This also assumes the encoder signal is a compatible (TTL A/B quadrature) type. If you have no backlash, it might be a workable solution.

    Do the Indramat motors have encoders built in already? If not and the linear encoder doesn't work out, you'd need to fit a rotary encoder to each of the motors so the CNCdrives could work with them. You can buy suitable Haidenhain clone encoders from China for peanuts. Failing that, you'd probably be looking at acquiring some proper AC servos which would cost a lot more and need mechanical buggerage to fit them where the Indramats were. Not sure I'd want to waste my time and money fitting steppers to a decent machine like this.

    Be aware that early analogue DC brushed systems often had tachometers mounted in the motors. They can't be used as encoders, as they only report speed, not position. However, you could remove them and use the freed up space to mount encoders.

  12. #19
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 11 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 8,408. Received thanks 1,440 times, giving thanks to others 108 times. Referred 1 members to the community.
    Quote Originally Posted by Muzzer View Post
    You could try connecting the DRO encoders to a DC servo drive but unless you had near-zero backlash, the drive could be almost impossible to tune. This also assumes the encoder signal is a compatible (TTL A/B quadrature) type. If you have no backlash, it might be a workable solution.
    Don't think these will be your typical magnetic linear encoders you see used on DRO's. These will be full blown Glass linear scales that are much more accurate and commonly used on high end machines.

    If it was me I'd get the details of the Linear scales and drop CNCdrive an email asking if they can be used. I think they will be able to be used but you might need to convert from Single ended to Differential, which isn't a big issue. But they will be the one's to tell you, but they will need details.

    Regards Steppers or Servo's then like I said if you want it cheap go with steppers as they will get the job done, maybe not as fast or smooth, but still done and reliable along with simple.!

  13. #20
    Quote Originally Posted by Muzzer View Post
    . Imagine trying to drive a car down a windy road with half a turn of lost movement on the steering wheel, then trying to fix that by adding some form of simple closed loop.
    I can identify with that having once borrowed a friends Series 1 LandRover that had 30...40 degrees play in the steering wheel before anything happened

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