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Author Topic: Newbie cant tune motors - Gecko540 & Mach3  (Read 6864 times)

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Newbie cant tune motors - Gecko540 & Mach3
« on: December 28, 2011, 12:02:54 PM »
Hi - been reading this site for some time while I been building my DIY router, and I've learned a lot so far.  I finally got my controller and motors and I'm bench testing things to see how much I've learned (unfortunately it doesn't seem to be enough).

Here’s what I’ve got for my system:

Mechanical – 5/8-8 acme screws direct coupled to stepper motor – 1600 steps per inch
Electrical – Gecko 540 control module with Keling KL23H2100-35-4B motors – 48V10A power supply – complete kit from Automation Technology
Computer – Gateway P3 997Mhz 256Ram – XP Pro SP2 – running Mach3

The problem I’m encountering is I can’t seem to tune the motors.  Through the software, when I try jogging using the arrow keys, the motors hum and vibrate loudly – sometimes they will rotate – sometimes they will switch directions, but I can’t switch back and forth repeatably – most times the motors are stalled.  This occurs with both x and y axis.  I have to set the accel and velocity very high to get any rotation out of them.

Troubleshooting so far
1.   Ran the driver test – getting Pulsing Too Fast at start – then under Mach control systems shows excellent – CPU-997  Shortest-37.556 Longest-41.313 – the graph shows very little distortion.
2.   Reconfirmed wiring Yellow Pin 9, Green Pin 8, Red Pin 7 and Blue Pin 6 – I have a 3.6k resistor between Pine 1 & 5 – all solder joints look clean and tight.
3.   Measured each pin of 25DB cable to confirm cable was straight through
4.   Measure voltage at pins 1-9 across pin 25 – getting 3.2 volts ?????
5.   Loaded the XML file from Gecko – system gave green light right away – renamed file CNC-Router and have been playing with it.

Attached is my XML file as to how I’ve got things setup so far.  I’m sure its something obvious, but as a newbie I totally out of ideas to try.

Thanks for any help provided !!!!
 
Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #1 on: December 28, 2011, 01:00:35 PM »
That's usually caused by the step signal being inverted.  If your drives are set up for 5V commons, "Step Low Active" on the ports and pins page should be checked.  If it's set up for ground commons, "Step Low Active" should be un-checked.  If that signal is inverted, you'll get a lot of strange behavior.  You might get some movement but it will be erratic with a growling sound.

Offline Hood

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Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #2 on: December 28, 2011, 02:33:52 PM »
You will need more than 1600 steps per inch as the Geckos are 10 microstepping drives so it will be 8 x 200 x 10 = 16,000

Hood
Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #3 on: December 28, 2011, 03:43:34 PM »
Thanks for the feedback !!!

OK adjusted steps to 16000 and I'm getting the motors to rotate more frequent, but still locking up and not switching rotation occasionally.
Played with the "Step low active" - either checked or unchecked I still get no improvements.

I switched the A+/A- and B+/B- wiring on the pins on one drive but it still reacts the same.

Offline Hood

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Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #4 on: December 28, 2011, 04:00:56 PM »
I would try with accel and velocity a lot lower than you have to see if that helps, maybe 50 for Vel and 5 for accel then you can increase if it helps. Also increase the pulse and step widths on Motor tuning, try 5 or maybe even 10
Hood
Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #5 on: December 28, 2011, 07:34:37 PM »
Thanks !!!

So far the best settings for velocity and accel are 70 and 15 repsectively - going lower results in no rotation.  Attached are the Mach3 settings I'm using, the 9pin wiring for the G540 and a link to a quick video showing the motion I'm getting.

Is there a simple way to bypass the computer/Mach3 and activate the drive directly.  I'm thinking it will help isolate whether its a hardware or computer/software issue.

Thanks again - Steve
http://s384.photobucket.com/albums/oo284/turdmagnet/?action=view&current=Motion.mp4
Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #6 on: December 28, 2011, 08:41:18 PM »
A couple of things come to mind.  If you're looking for a decent feedrate, at 16000 steps per, you'll have to spin those motors real fast.  (1) 48V is probably not enough to do that unless the motor inductance is very low.  Still may not be enough. (2) Once you start running at high RPM, motor torque falls off quickly.  You can address that by throwing more voltage at it, but your motors still sound a bit small.  Your motors are pretty small to begin with and they are turning a large screw direct. 

Offline ger21

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Re: Newbie cant tune motors - Gecko540 & Mach3
« Reply #7 on: December 28, 2011, 09:26:18 PM »
2 things.
1) When running motors on a bench or table, they generally won't run nearly as well as they will when mounted to the machine.

2) I see similar posts (about G540's) on CNC Zone very frequently. The usual cause is a weak parallel port. If you can, try using another PC.
Gerry

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