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  1. #1
    Being in a hurry and not wanting to drop a big wad of cash yet, I decided on an eBay 6040 to get me started. I went for 800W spindle with the standard 1500W VFD and the blue controller box from hell, but I made sure it was a recent version with 3 separate M542 drivers rather than an all in one pcb.

    The long axis (labelled Y and that's probably what I'll call it) has one 1605 ballscrew driving the gantry, with SBR16 supported round rails. Cross axis and Z are unsupported 20mm and 12mm round rails.

    First worry was the low quality of the mounting of the 1605 screws, just a washer (or not) and a badly made (wonky) nyloc nut. I tightened it all up just a bit more than finger tight. The X drive is a bit graunchy at times, in one direction only. Any ideas on what that might be? corrosion of the bearings? badly made ballnut? I intend to take it apart and fiddle with the mechanical bits before I run it in anger.

    What sort of lubrication does a ballscrew need?

    Next problem was that on and off (mostly on) and for a prolonged period when it happens, x+ and z+ wouldn't jog after doing y+. but doing y- would make them work again. I swapped the X and Y leads at the control box, and the problem switched axes. Therefore the problem is inside the control box, either the BOB or the M542s. I will swap the M542s next and test the grounds. See if that helps or tells me more.

    Final thing fo rthe moment, how do I swap axis directions in Mach3 ? currently Z+ is down on my machine?

    I've checked the VFD setting and run the spindle up to speed. Not plumbed the pump yet. How long can I run the spindle without cooling?
    Last edited by jimbo_cnc; 25-08-2014 at 08:38 PM. Reason: rails correction

  2. #2
    Answer to some of your points.

    Not saying this is your problem but I had ball trouble too, see here for how I solved it; http://www.mycncuk.com/threads/6565-...6350#post56350
    If you run the ball nut up and down by hand you will see if the problem lies with that, it could be the end bearings or the screw is bent, http://www.mycncuk.com/threads/6565-...6172#post56172 or it's mounted out of line. I also had problems with the BK type bearings blocks but not sure if yours uses that type. http://www.mycncuk.com/threads/6565-...6128#post56128

    This is the right grease for linear bearings as well, some people use oil for both instead of grease.
    http://www.toolstation.com/shop/Auto...0/sd180/p89691

    On the Ports and Pins / Motor Outputs screen, if you want to reverse the directions of any of the axes, toggle the "Dir Low Active" checkbox for that motor.

    Good thread here about spindles cooling etc.
    http://www.mycncuk.com/threads/5814-...nd-Advice-More
    Last edited by EddyCurrent; 25-08-2014 at 07:40 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  3. #3
    Thanks Eddy, will have a read now.

    I'm pretty sure I've narrowed the controller problem down to the BOB ( I knew having separate drivers would pay off :) ). Each axis works OK by itself when other are unplugged. And swapping the BOB outputs to different M542s moves the problem axes around.

    I should take the long axis drive apart now and inspect, so that I can email the seller with all the bits I want replaced in one go.

  4. #4
    Oh yes, the M5642 drivers were set at 16 microsteps. I changed this to 8 but it made no difference. Is it worth trying other micro-step settings?

    Would I be right to assume that smaller (more) steps is harder for the electronics to do / more likely to go wrong ?

  5. #5
    Quote Originally Posted by jimbowley View Post
    Would I be right to assume that smaller (more) steps is harder for the electronics to do / more likely to go wrong ?
    No it's the Parallel port that struggles not the electronics. The higher the steps the more pulses required for the same distance hence why the higher the step count the slower the machine can be tuned with the set Kernal speed in Mach3.

    Going higher on the steps helps smooth the motors but works the PP harder and this can cause missed steps if it's struggling.

    8 is a good setting and I would leave it there.

    Regards the drive problems check the STep & Dir connections at the drive giving the trouble this as been a cause of trouble in the past on these machines along with shity wire quality.

    Spindle will run for ages 1 hour + without cooling if not under load. I've often cut small jobs without turning my pump on.

  6. #6
    Not sure if your aware or not but if you change the MS you will need to re-tune the motors Step per setting.?

    Also don't run higher than 45Khz kernal speed in Mach3 other wise your opening your self up to potential problems. Best to keep at 25Khz or if must then 35Khz but don't change unless you really can't get the speeds you would like.
    Last edited by JAZZCNC; 25-08-2014 at 09:36 PM.

  7. #7
    Quote Originally Posted by JAZZCNC View Post
    Regards the drive problems check the STep & Dir connections at the drive giving the trouble this as been a cause of trouble in the past on these machines along with shity wire quality.
    I'm not familiar with what the diffferent wires are, but the BOB has a 4pin connector for each axis. 3 of the 4 pins are used and the 4th pin has a loose wire hanging from it. The BOB looks like it has also the option of output via screw terminals, so I could cut the terminal blocks off and use those. But I'm wary of doing that before I hear from the seller, and if I get a replacement BOB Id rather just plug it in.

    The wiring all looks pretty nice to me, but I'm not an electrics person. All the sockets into the controller feel like plastic, but they are conductive, I've tested the continuity of the casing.

    Just grabbed this pic of my BOB from ebayClick image for larger version. 

Name:	BOB_57.JPG 
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    Last edited by jimbo_cnc; 25-08-2014 at 10:03 PM.

  8. #8
    Ok well I'm not a fan of those silly plugs and I'd wire to the terminals every time but your correct to wait untill seller responds.

    That said if the problem moved then it won't be the BOB and chances are it's a drive or wiring to drive.? . . Again I would check the connections at the drives.

  9. #9
    I moved the outputs of the BOB to different drivers. So the problem changing axis shows that the driver is not the problem as the problem follows the BOB output independent of which driver it is wired to.

    Here is a boring video of the 2 problems.
    https://www.youtube.com/watch?v=IoAGHdbffnQ

  10. #10
    Using the red LED's on the drivers as diagnostics, what happens when everthing is connected apart from all the motors ? i.e. just unplug all the motrs, does the fault still happen ? DO NOT unplug them with power on, it will probably blow the drivers.
    Last edited by EddyCurrent; 26-08-2014 at 02:22 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

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