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Offline c30232

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Control crash, CNC router?
« on: February 12, 2014, 03:53:19 AM »
4' X 8' 3 axis gantry with 4 motors.  Y and A are slaved

I have advanced from jogging and homing to running an 8" x  8" carving that took about 4 1/2 hours of run time.  Life was good and I thought it was time to run the router problem free.  However, during a table surfacing operation I experienced a crash or runaway machine.  The operation is thus:

Z is constant at table level

Y moves positive the diameter of the cutter and holds

X moves the width of the table.

Y is a two motor gantry slaved with A counter rotating

During the operation X stopped its travel and Y attempted to move without command, however, A is reversed.  The event occurred three times with varied movements of X and Z, but all included the similar Y movement and resulting gantry torquing.

Any ideas where the destructive commands are coming from?     


Offline Hood

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Re: Control crash, CNC router?
« Reply #1 on: February 12, 2014, 08:22:22 AM »
Attach your xml and I will have a look at your config, also what version of Mach are you using so I can simulate with it.
Hood

Offline c30232

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Re: Control crash, CNC router?
« Reply #2 on: February 12, 2014, 08:40:42 AM »
Thanks,

I believe the only thing messed with after the carving was the soft limits and CV mode.  We had problems with the limits as you will see they are not set.

Offline c30232

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Re: Control crash, CNC router?
« Reply #3 on: February 12, 2014, 08:45:08 AM »
Version R3.043.066  I believe this is correct.  I will check the machine later.

Offline Hood

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Re: Control crash, CNC router?
« Reply #4 on: February 12, 2014, 09:27:56 AM »
xml looks fine, assuming you are not on the edge with your motor tuning.

So next question, when things went haywire, did the DROs in Mach correspond to the weird positions r were they where it should have been?
Also did you hear unusual noises from the motors?
Hood

Offline c30232

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Re: Control crash, CNC router?
« Reply #5 on: February 12, 2014, 11:55:46 AM »
The machine is wired in temporary rats nest format thus the scramble to shut it down is distracting.  Because of the racking of the gantry, it's not something to replicate and document.

Mach may be running as though nothing went wrong.  I am confident this is the case, but I will make better note if it occurs again.

There are three power downs

1)  Power to the driver which is the first to hit.

2) Mach

3) The power to the BOB

Mach may be running okay and has no effect during a screen e-stop.

When the power is restored to the drivers, the crash heats up again with Mach in Reset/E-Stop

A power down of the BOB releases control and the drivers can be re-powered and Mach is good to go.

It is to hard to hear over the other equipment, however, nothing seems off with the steppers.  Remember Y is at rest when this occurs.  It seems that A gets a go signal and because of racking it is not so far not possible to determine if Y is running also.  The last crash was in the opposite direction of the others.

There are indicator lights on the BOB.  I do not speak their language, however, there are 4 red lights that seem to indicate a direction . . . perhaps they are modal.  Thus when Y is in motion only on of the two axis, Y/A, lights is on.  One light for this direction and the other light for that direction . . . never both.  After/during the crash both A and Y are on.



 




   

Offline c30232

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Re: Control crash, CNC router?
« Reply #6 on: February 12, 2014, 12:06:15 PM »
The machine must be homed after the crash further supporting the Mach is doing its thing.  Here is a link to the BOB.  I have been unable to acquire documentation . . . I am in contact with Campbell but still no docs.  I bought the BOB new . . . go figure.

 http://campbelldesigns.net/Combo-board.php

Offline Hood

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Re: Control crash, CNC router?
« Reply #7 on: February 12, 2014, 01:22:31 PM »
Rats nest is not good when using low voltage signals :( That could well be one of the issues as its easy for noise to get into the wires and affect things.

I think the motor tuning parameters for a slaved axis is irrelevant but I am not 100% sure so make sure the A is set to same steps per unit and Velocity/accel as the Y.
Even if the motor parameters dont matter I would think it is possible to change the active state of the Dir pin on a slaved axis to make it go the opposite way, if that is the case then the Dir LEDs may be correct with one off and one on as it will depend how you have the motors wired and also whether the motors are at the same end or opposite.


If Mach is indeed showing the position correctly when the axes go wild then I would say it is most likely noise or loose connections that are your problem.

Hood

Offline c30232

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Re: Control crash, CNC router?
« Reply #8 on: February 12, 2014, 02:20:19 PM »
Well . . . it is an orderly nest and certainly not as constrained or twisted as when confined to its enclosure.  Please give it some more thought.  It is at rest and seemingly the BOB get a ghost signal to go crazy.  The BOB is isolated . . . I think.  If it is noise, why didn't show during the multi hour carving run?  The time for that run was actually 4 1/2 hours.

I could believe a poor connection.  I pound my trusty assistant not to Gorilla-hand stuff and I get loose instead.    What connection would set that condition?  I though it could be a short triggered by position, but that seems to be ruled out.  Hmm, I was focused on Y.  The X was near the same location during all crashes . . . about mid travel.  The motor wires are shielded, but the terminations are not.  Could a short do the job?  If yes, how does it reset itself?

I will check the mechanical connections and give it a go.

When A is slaved, all else seems null as far as Mach . . . I think.   I will set them mirrored to be sure.  The direction lights are proper because a slaved movement has to different directions of rotation.

Thanks!!!   

     

Offline Hood

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Re: Control crash, CNC router?
« Reply #9 on: February 12, 2014, 04:26:26 PM »
Thought that was the way it was with slaved but been so long since I did have a slave set up (was on the coil winder) that I couldnt be sure.
Regarding shields, they need to be grounded or could potentially cause more issues than without, presume that is what you mean by not terminated.
Step/Dir wires should ideally be shielded, in fact all low voltage signalling should be.

The slaved motors rotation direction will depend how you are set up, sounds like you must have one screw with two motors either end but anyway doesnt matter, if its the correct way for your setup then the LEDs on the BOB should always be the same. Noise however could easily get in and change them.

So the thing you need to find out is if Mach shows correctly when axis are weird, if it does then its almost certainly external issues.

Hood