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Author Topic: MDI movement using G-Code different to jogging  (Read 3868 times)

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MDI movement using G-Code different to jogging
« on: March 08, 2015, 11:30:16 PM »
Hi All,

I am finalising the setup of my new machine and have discovered something I don't understand.
I have setup a pen where my end mill will be to test that all works correctly.

If I set the pen on some paper and zero all axis I can draw a perfect 2 inch by 2 inch square by just jogging the X and Y axis to 2.0 and back while watching the RDOs.
I assume this means I've managed to set the motor and axis parameters correctly.

So I moved to issuing MDI G-code commands to start learning what is what.
But if I, again, put the pen on the paper and zero the machine and then issue a G01 X2.0 command, I expected the machine to move 2.0 inches on the X axis.
It didn't. It moved 0.8142 inches.
To make matters worse, if I now press "Go To Zero" the X axis moves but ends up at -0.2576 in the RDO.

I stuffed up somewhere. Can any one help?

Offline BR549

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Re: MDI movement using G-Code different to jogging
« Reply #1 on: March 09, 2015, 01:03:11 AM »
OK first you need to specific WHAT motion controller you are using.

(;-) TP
Re: MDI movement using G-Code different to jogging
« Reply #2 on: March 09, 2015, 02:35:00 AM »
Ah, of course. My bad.

I have the PMDX-422 SmartBobUSB
MACH 4 build 4.0.1.2230 on Windows 7
Re: MDI movement using G-Code different to jogging
« Reply #3 on: March 09, 2015, 12:07:52 PM »
OK - we will need a bit *more* information.  I see you are using Mach4 build 2230.  What PMDX-SmartBOB plugin version and firmware version are you running?  To get this info, go to the "Configure" menu and select "Plugins...", then click on the "Configure" button next to the PMDX-SmartBOB-USB plugin.  The first screen will list all of the relevant info.

Hmmmm....  Now that I look at your post again, a possible cause of this kind of problem is that you have the motor's max velocity set too high.  By default, Mach4 sets the jogging speed to 50% of max velocity.  You can see this when you click on the "Jogging" tab in the lower portion of the Mach4 screen set.  There is a slider at the bottom and a "Jog Rate" box.  Try setting the jog rate to 100% and see if jogging reproduces the same motion anomalies as GCode motion.  If so, go to the "Configure" menu and select "Mach...", then click on the "Motors" tab and try setting the "Velocity" field to a lower value.  If that doesn't fix things, then please post the above info.

Bob
Re: MDI movement using G-Code different to jogging
« Reply #4 on: March 09, 2015, 01:53:45 PM »
Oops ... Ignore that man behind the curtain.  Motor velocity settings will NOT cause that problem.  If the velocity was too high the DROs would show the correct value and the machine would move less than that.

So, please post your plug-in and firmware information.  And re-comfirm the Mach4 build number.  We have had issues between our plug-in and Mach4 with the latest builds (2255 and 2259), but not 2230.  So this may be some other issue.

Bob
Re: MDI movement using G-Code different to jogging
« Reply #5 on: March 09, 2015, 05:29:00 PM »
Confirming:

Mach4 build 4.0.1.2230
SmartBobUSB Plugin version 0.17.86
Boot loader: 1.5.58
Firmware: 0.32.104

I have the Velocity Units/Minute set to 31 for all motors.
« Last Edit: March 09, 2015, 05:40:36 PM by NeilD321 »
Re: MDI movement using G-Code different to jogging
« Reply #6 on: March 10, 2015, 08:23:13 AM »
Rats, no quick solutions off the top of my head.  Since this is heading into detailed debugging of the PMDX-SmartBOB I would like to move this discussion over to our support forums (http://www.pmdx.com/PMDX_Forums).  While Steve and I do try to keep an eye on messages here, our forums are our primary support site.

I've copied the important info from this thread onto our forums here:
http://www.pmdx.com/PMDX-Forums/index.php?topic=72.0

Please go visit there (yeah, I know... and create another account) and we will work to figure out what is happening.

Bob at PMDX

Offline BR549

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Re: MDI movement using G-Code different to jogging
« Reply #7 on: March 10, 2015, 12:28:39 PM »
One thing for sure is you HAVE to calibrate the machine running Gcode NOT jogging.

Set your steps per and test with the MDI line using Gcode moves ONLY. The rest will fall into place on its own.

(;-) TP
Re: MDI movement using G-Code different to jogging
« Reply #8 on: March 10, 2015, 05:54:17 PM »
Thanks BR549. I'll keep that in mind.