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  1. #11
    It's just a theory and I still suspect the PC to bob cable.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  2. #12
    your sort of thinking the wrong way round with this.

    You may have a problem with interference from many things in the workshop, and isolating them all would not be possible.

    Its the data lines between PC>BOB and sometimes BOB>MOTORS that you need to make sure is insulated from everything else, swap out that parallel for another one.

    Its also the only place apart from the BOB, that you can interfare with the motor timings and estops and motor direction at the same time.

    Let me add this though, i have never worked with plasma gear so i dont understand what fields that creates, or what extra current/dump loads it uses. So there may be something obvious am missing

  3. #13
    Quote Originally Posted by Davek0974 View Post
    i don't see how it can be the bob as that would not affect the dro's which are running way too fast.
    Bob's are sneaky bastards they trick you into thinking they are fine so you go round in circles chasing other things but then you end up back at the BOb and soon has you change them out every thing works fine.!!

    Also if you have noise it won't affect the software or the DRO's it will only affect I/O's so causing trips or lost signals. When you say DRO's are running fast what exactly do you mean.?
    Mach's DRO's only show the pulses sent out the parallel port so could be that they are sending the correct pulses for the speed but motors/drives are not getting them.? This could be BOB or PP and if you say driver test shows it's fine then BOB would be my first port of call. Thou changing the PP cable is always good place to start.

    My first cause of action would be going over all the wiring and connections again with a fine tooth comb. Then trying another PC and PP cable if available or very least re-installing Mach and creating a new XML. Then if no differant go straight for the BOB.

    If still no differant After that lot then I'd be concerned and scratching my head.!!

  4. Just been messing about again and noticed that there is an LED on the BOB, this is on normally, but after running the axes up and down manually a bit, the LED flashed off then on and Mach threw the "e-stop requested" error, after that the torch relay will not trigger and the axes start messing about.

    I really can't believe I've fried a BOB or the PC surely?

    If that is the case then there is little hope of success as I have done almost everything I can to shield this stuff, I have not driven a ground rod yet as its in the factory at work and i doubt the landlord would appreciate that :)

    I could understand it if I hadn't connected the plasma ground lead or something else stupid but I even checked it with a meter to the work-piece first!

    I will need to order a parallel cable as they are not standard ones and have two DB connectors whereas a parallel lead has a centronics on one end, got boxes full of them :(

    I will disconnect the motor drives and watch that LED for a test. I'll also ring cnc4you and see exactly what that LED indicates.

    I might be able to pinch another PC but even if that works, I wouldn't risk another test without discovering the point of destruction.

  5. Spoke to the BOB suppliers, seems the BOB is fried 100%. (:

    They also said it was wired wrongly, I had the BOB supply fed from the Z-axis output of the main PSU, apparently that is bad and must be a separate regulated supply for the BOB only.

    Anyone know anything about this?

  6. Quote Originally Posted by Davek0974 View Post
    Spoke to the BOB suppliers, seems the BOB is fried 100%. (:

    They also said it was wired wrongly, I had the BOB supply fed from the Z-axis output of the main PSU, apparently that is bad and must be a separate regulated supply for the BOB only.

    Anyone know anything about this?
    Dave It would be helpful for you to give the model number of the BOB and the type of power supply, Voltage and a wiring diagram of how you have connected it up. Then you might be able to get the correct advise from here. It is difficult for people to have vague information and give proper advise. ..Clive

  7. Quote Originally Posted by Clive S View Post
    Dave It would be helpful for you to give the model number of the BOB and the type of power supply, Voltage and a wiring diagram of how you have connected it up. Then you might be able to get the correct advise from here. It is difficult for people to have vague information and give proper advise. ..Clive
    I can fully understand that, but the diagram is in my head, however its currently like this basically...

    1 - I have an 11A smps connected to the three motor drives,

    2 - a smaller 24v smps connected to the BOB,

    3 - The BOB is a cnc4you.co.uk HG07 unit - Breakout board CNC Stepper Motor 5 Axis Spindle Relay HG08

    4 - Another small 24v psu is running the relays for e-stop and limits / torch trigger.

    5 - I have used screened cable for all motor leads, this is connected at one end only inside the cabinet to a star ground.

    6 - I have connected the Z-axis to the X-axis carriage and then back to the star point.

    7 - I have connected the Y-axis gantry to the star point.

    8 - The case of the PC is connected to the star point.

    9 - All PC leads are fitted with ferrite chokes.

    10 - The mains is now filtered at the plug.

    11 - The plasma ground lead is clamped to the cutting bed.

    12 - The frame of the table (and therefore the cutting bed) is not connected directly to my star point, I am guessing this is catered for by having the cabinet bolted direct?

    The whole lot is mounted in a steel cabinet bolted to the machine frame.
    Last edited by Davek0974; 07-03-2014 at 01:34 PM.

  8. I can fully understand that, but the diagram is in my head, however its currently like this basically...

    1 - I have an 11A smps connected to the three motor drives,

    2 - a smaller 24v smps connected to the BOB,

    3 - The BOB is a cnc4you.co.uk HG07 unit - Breakout board CNC Stepper Motor 5 Axis Spindle Relay HG08
    Ok Dave what is the o/p voltage from the 11A p/s. It states on their data sheet that when using a plasma you have to use a separate p/s for the BOB (that is normal anyway).
    re this (They also said it was wired wrongly, I had the BOB supply fed from the Z-axis output of the main PSU) if that is the case what is the purpose of the smaller 24V p/s connect to the BOB

    In my humble opinion smps are crap for motors and you would have been better off with a toroidal type none regulated.


    Don't get despondent there are enough people on here to help out if you give the information that is required ..Clive

  9. It's a 36v unit.

    The leaflet i have with the bob states "you can use your regulated DC motor PSU if not exceeding 55v" no mention of plasma warnings etc so they must have updated the data, this is why i originally had it wired to the motor PSU.

    Will look into a linear toroidal type psu.

  10. Dave You also stated that you had a 24V p/s was this connected at the same time if so how? ..Clive

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