Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Rimmel on April 08, 2014, 12:03:26 PM

Title: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on April 08, 2014, 12:03:26 PM: Got a part I'm making that is basically a large grub/set screw with a m0.75 thread - it is a 3 part process:

1) Shape part and put thread on (program 1)

2) Manually broach internal hex

3) Part off (program 2)

This process works fine, but randomly the steppers stop at the G76 line. However the Z index still shows the axis moving in Mach3.

Anyone got any ideas?
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Hood on April 08, 2014, 02:44:29 PM: Quote from: Rimmel on April 08, 2014, 12:03:26 PM
However the Z index still shows the axis moving in Mach3.

Anyone got any ideas?

Not really clear on what you are meaning, is this the INDEX LED that is still showing or are you meaning the Z axis DRO is still showing the motion even though your axis is not moving?

If the latter then it would seem you have a problem with either the step signals not getting to your drive or maybe even your motor is, for some reason, stalling. For the latter you should hear if it is stalling.
It could even be something slack on your machine such as a coupling.

Hood
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on April 08, 2014, 02:57:12 PM: The DRO shows movement but the motor wont move. I don't think it's stalling.

Thing is it will work for 5 - 10 runs and then just stop and it is always on the exact same place.

When using the G76, are there any cancel codes etc that I should use? before and after. (just trying to rules things out)

thanks for the reply
Rim
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Hood on April 08, 2014, 03:04:04 PM: If the DRO is moving then your issue is almost certainly external to Mach, probably something like a loose connection or a faulty breakout board (bad opto or something) or even a drive overheating.
Hood
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on April 08, 2014, 03:13:59 PM: OK thanks - I will check all the connections.

thanks again for the help.

regards
Rim
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on April 08, 2014, 03:22:02 PM: Although - a bit strange that it fails on exactly the same point. That would suggest a software problem. ?
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Hood on April 09, 2014, 03:03:06 AM: If you are using the parallel port then the DROs get updated from the drivers output, so if they are moving when the motor is not, the fault is almost certain to be external of the computer.
Hood
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on April 09, 2014, 06:20:19 AM: I see - I am using a UC100.

I will check the wiring.

thanks
Rim
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Hood on April 10, 2014, 03:29:19 AM: With you using an external controller then things may be different.
From my understanding the DROs in Mach are updated in a similar manner as the PP, when using an external controller. What I mean by that is, when using the PP it is the pulses output from the driver that updates the DROs in Mach. When using an external controller the same happens, it is the controller that will update the DROs in Mach.
The difference however may be that the external controller is updating the DROs but not actually using the pulse output to get that data. You would really need to ask CNCDrives to look into it unless you have a scope and can test for yourself. If you do have a scope then it will be easy to see if the pulses are being output from the UC100 when the motors are not, but should be, moving.

Hood
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on May 24, 2014, 01:31:10 PM: CNCdrives claim it is a stepper motor problem, however I changed over to a ESS controller and the problem vanished. I ran with the ESS for 4 hours constant with no problem. I then changed back and the problem appeared again after only the second run. :o

So the ESS fixed that problem, but has interference problems of it's own that the UC100 never had. Even though the ESS is supposed to be more robust in noisy environments it actually fails where a USB controller does not.

??? ??? ??? ??? ??? ???
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on May 24, 2014, 02:48:21 PM: Oooooooooooh heres something interesting - when the program fails at the G76 line then it doesn't actually fail in the fact that the steppers do not work - it fails because mach3 fails to go into "mm/rev" mode. it stays in "mm/min" mode, so the steppers are moving but at a really slow rate as it is a 0.75 pitch thread so it's actually doing 0.75mm per minute!

Heres the test g-code.

Quote
G18 G21 G64 G80 G90 G40 G49 G94
GO Z50 X50
M0 ( TOOL 05 )
M3 S800
G0 G90 Z5 X9.84
G4 P1000
G76 X8.95 Z-21 Q2 P0.75 J0.03 L45 H0.05 I29 C0.3 B0.01 T0
G80 (CANCEL CANNED CYCLE)
G0 Z50 X50
M30

Any ideas?

thanks
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on May 24, 2014, 03:28:49 PM: Fixed it - I added "G95" just before the G76 line and it works fine now!

thanks
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: 1Acnc on May 25, 2014, 03:09:44 PM: I have a similar problem, If I stop the program and maybe re-Zero the Z ,that the DRO will sometime run but no stepper movement. I have found if I cycle the E-stop after making a change and then restarting, have not had the problem. I am using a parallel port. I am new so I maybe doing things that I should not be doing.
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: 1Acnc on May 25, 2014, 04:17:37 PM: That should have been Reset not E-Stop
Title: Re: Mach3 steppers stop on G76 - but not all the time
Post by: Rimmel on May 25, 2014, 05:06:19 PM: I found out the G95 trick because someone else had the same problem.