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  1. #21
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 9 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.
    When you say full blown glass linear scales, that's what most of your Chinesium scales are these days. I have several sets, for my smaller mill and my lathe. They are both single ended TTL output, which is what the CNCdrive servos are looking for - I have those drives on my Shizuoka, so I'm familiar with them. They would certainly connect up OK but whether they'd be happy driving an old machine with backlash would remain to be seen.

    The accuracy is down to what you want to pay. I think mine are the basic 5um ones from HXX in Shenzhen but you can get resolution down to 0.1um from them and others.

    It's possible that high end ones might have differential outputs which are more noise immune, in which case you'd need a line driver to TTL converter.

    Whatever encoder you end up with, the driver needs to know how many pulses per rev. This will be a function of the ballscrew pitch, belt reduction ratio and linear encoder resolution but the sums are very simple.

  2. #22
    Ok, so some info I have found about the motors which also seems to match what's on the motor plates (photo attached):

    permanent magnet DC servo motors
    2000RPM
    170V DC
    tachometer mounted on rear (I think.. photo attached), but no idea of what output this gives...

    with regards to the backlash and scale accuracy asked previously..
    They are Anilam linear scales with 0.01mm resolution, again no idea of output type but photo attached if anyone might recognise it.

    Done some measurements on the backlash, it's a lot worse than I thought to be fair!
    X: 0.15mm
    Y:0.04mm
    Z:0.06mm

    On a side note, the X axis moves faster than the pitch of the ball screw, does that mean there will be some kind of gearbox on the ball screw itself?

    Like I say accuracy isn't of too high importance with this, I can sneak high accuracy stuff into lunch breaks at work if I do need that.
    The main type of work I will be doing on it is very agricultural low tolerance stuff that I can't always get away with at work ! In all honesty I don't really need CNC functionality for most of it, its just a nice bonus to have!

    With all that taken into account, Is a stepper setup going to be best for me? I know its probably not the best end result for the machine but it will keep it nice and simple for me to convert and use for now.

    It would be nice to keep all the original motors but its sounds like it may be a bit more complicated to get running?

    Or will this be realistically unusable as a CNC with that amount of backlash until I get that sorted?
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  3. #23
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 9 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.
    That is a tacho you are looking at. They have no purpose nowadays, what with digital drives. You should try to remove it to see what the end of the rotor shaft looks like. A rotary encoder typically has a small (6mm or so) shaft and creates negligible torque drag, so mounting one in place of the tacho could be quite simple. Something like this Chinesium clone would be suitable https://www.ebay.com/itm/OMRON-Rotar...g/332386539771

    One of those CNCdrive brushed servo drivers would be fine for a motor like that and the encoder would connect directly to it. https://www.cncdrive.com/DG4S_16035.html The bigger one is rated at 160V / 45A and although your motor is rated at 100A, it's a beast (47Nm!), so you can probably manage very nicely with half of that. The advantage of going this route would be minimal messing with the mechanical parts. You can probably just leave the encoders where they are for now unless you could hook them up with one of the Chinesium DRO displays just to frighten yourself.

    This would be a good time to get a parts list / exploded / section view / manual for the machine. There's a good chance TOS would still have documentation, or you might find a user who could scan one for you. Then you can see how to dismantle it and how it works.

    I would expect that the ballscrews will be fitted with double ballnuts, so you'd have some degree of adjustment for taking up some of the backlash. There's likely to be two ballnuts with a shim between them. You can fit additional shims to reduce backlash, possibly without having to even remove the ballscrew. Going to the extreme of fitting bigger ball bearings would likely require you to dismantle the machine, which is quite a large beast.

  4. #24
    Sounds like we might have a plan here then, I think you've convinced me to keep the motors on it and go for those drivers.

    So in terms of parts I need to purchase:

    -Three servo drives (the ones you linked me to)
    -Three Rotary encoders for back end of motors ( I'll make them fit somehow I'm sure!)
    -Breakout board to link drivers to PC? (this is where I start getting a bit confused...)
    -PC control software (any recommendations that would be compatible with all these parts?)

    I must be missing lots of other stuff I'm sure?


    Before I order anything I think I'll give it a bit of a strip down and try and sort out some of the backlash issues. Good idea about the machine drawings, I'll see what is around.

  5. #25
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 9 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.
    I'd agree it's probably the plan with least effort, least cost and best performance although there may doubtless be other opinions. I don't have any particular technology to promote, having closed loop steppers, DC brushed servos and AC servos on my machines. But my Shizuoka is similar to your TOS ie old and solidly built with old but well specified motors, so it sounds very similar in many ways. The controller on that thing also came from the ark.

    Almost any controller will do as long as it outputs step and direction signals and has some spare IO. My machines have Centroid Acorn (the Shiz) and Newker 990MDCa (Bridgeport) and they both have their pros and cons. Can't comment on other controllers from personal experience but I've heard UCCNC also good. They are from the same place as the DC servos (CNCdrive).

    I quite like the Acorn but it requires a PC to run on and the cost adds up by the time you've got the full cream licence and expansion board. The Newker is pretty good value at under 400 being fully self contained but the Chinglish has been a bit of a hurdle. I prefer the Acorn of the 2 but as I say, I have little experience beyond them unless you count a near miss with LinuxCNC.

    Would be interesting to see the manual if you can find one. I have one for my Shiz and it made rebuilding it considerably easier than it might otherwise have been.

  6. #26
    Just having a look at the centroid Acorn kit and its not too bad price wise but probably a little more than I can stretch at the minute.

    The UCCNC looks to be a good option with good reviews considering the price.

    would this combination get the mill running:

    3 of these: https://www.cncdrive.com/DG4S_16035.html
    1 of these: https://www.cncdrive.com/AXBB.html
    Software: https://www.cncdrive.com/UCCNC.html
    plus one 5VDC and 24VDC power supply
    and the three motor encoders

    Think I'm finally getting my head around it thanks to you guys!

  7. #27
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 9 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.
    Know what you mean about Acorn. By the time you've coughed up for the digitising (probing) version and the expansion board, you are at $1000 before you even find a PC to run it on. Then the wireless MPG is another $240. It works well and the support forum is very good, so I'm very happy with it. Depends if you have the dosh available.

    The AXBB looks pretty interesting. No experience of them but they seem to have all the bumps in the right places and the pricing looks attractive.

    FWIW, they also seem to sell several different encoders. Presumably they will be compatible with the controllers and the pricing seems similar.

    That looks about right for the kit of parts. I assume you have a main PSU from the original system that can supply the bulk power at around 140Vdc or so? I ended up getting a 120V 3kW isolation transformer from Screwfix and removing some turns from the secondary to get the right output, as the original 3 phase transformer was the size of a house..

  8. #28
    I did see the encoders on there as well, probably just worth getting it all from them, as you say it should all be compatible then!

    I've sent them over an email to check it is all going to work how I need, will have to wait and see if they get back to me or not though.

    I hadn't thought about the main power supply actually, good point! The current set up has a fairly substantial transformer unit that appears to output various voltages, I know there is a supply at around 140V in the unit supplying the current drives but can't remember if its DC, will have to check!

  9. #29
    Muzzer's Avatar
    Lives in Lytham St. Annes, United Kingdom. Last Activity: 9 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.
    If it's like mine, the DC was supplied from a massive three phase transformer. The winding would need to be about 100Vac so that you end up with around 140Vdc off load. Here's how I did mine, way back when https://mightyshiz.blogspot.com/2017...an-handle.html I welded the cores back up afterwards with the MIG.

    One additional component I bought was the braking module http://shop.cncdrive.com/index.php?productID=260. This allows you to decelerate quickly without risking overvoltage damage to the servo drivers. This clamps the voltage at around 180V. I must admit I haven't ever checked to see if it cuts in on my system but I didn't plan to risk my drivers to find out. One braking module would be enough per system.

  10. #30
    Just had a look through your web page, some good stuff on there, really useful!

    My transformer isn't quite the size that came on yours! I think I will repurpose what I have if possible. I found a 'specification sheet' for the transformer that seems to suggest that when used with the motors I have it should be set up to output 150V... but I may be reading it completely wrong! attached photo.

    The braking module seems like a good idea for the price of it, better than potentially spending another 300 on new drivers if they go bang!
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