[orbyog]

Built a machine with 1200oz steppers two on X one on Y and one for Z, driver boards are Gecko G201's controlled by a PMDX.com 131 breakout board and 34volt 20amp power supply (I had been running it at 68volts but dropped it down at the advice of Mariss) all controlled by Mach2 steady at 25,367mhz with X and A drives slaved. Steps are set to 10,020 which seemes to be the right number after measuring numerous times, I have the Velocity set at 2 and have tried almost every variable between 1 and 2.5 with Accelertaion set between 5 and 22.5.
The problem I am having is that when I run the G-code (any code) if I run at over 80ipm I get what I think you would call stalls, not at the same point every time or same axis for that matter but more often the X or A which skews the gantry. Every thing runs smooth as silk when jogging at any speed (tested upto 149ipm) but when running a job even an air cut I get inconsistant stalls. Any help would be appreciated.
BTW motors are direct connected to 5tpi screws which have been triple checked for any kind of mechanical problems. Thanks in advance.
Robert

Also forgot to mention although the motors apear to stall two grown men cannot stop (or even hesitate) the gantry from moving at any speed!

[ViperTX]

Maybe the gantry is binding.....

[orbyog]

Thanks for the reply .... but all mechanicals have been disassembled and inspected and verifyed no binding or resistance.
Also I didn't mention I also have tried four different computers thinging it may be a pulsing problem. Thanks again
Robert

[ger21]

How fast is the PC?

[orbyog]

PC1 = 1ghz 128mb
PC2 = 400mhz 512mb
PC3 = 1.2ghz 1gb
PC4 = 2.1ghz 512mb
all run Mach2 at 25,000hz or higher except the 400mhz which was 23,000hz

Trying to swap Gekco's around to different axis's now, I'm grasping at straws at this point.

[ger21]

Did it work OK at 68V? If so, I'd guess your reaching the upper limit of the motors. Have you tried using Mach3?

[orbyog]

The problem with the 68volts was one of the motors was buzzing and determined and replaced the Gecko, Mariss had felt the voltage was to high for the motor in use.

Tried Mach3 as far as making all the settings, but had a real problem with slaving the drives (x & A) when homing the motors want to run independantly to the home switch as you could imagine that is not a good thing (chair) jogging worked fine but I didn't want to take any chances.

[ger21]

I believe you need to change the code for the home button in Mach3 when using slaved axis. Here's the info I found on the yahoo group.

You need to edit the script in the RefAll button to ref the two axis at
the same time.

The command is

RefCombination( 9 )

That command will ref the X and A together. Try it as a test, open the VB
Scripter, type in that command and hit run, both shoudl home and
autosquare..

With the 68V, though, could you run OK at the faster speeds?

[orbyog]

Thanks for the Mach3 info. Even at the 68volts still had stalling.
Now change a bunch of things .... increase Mach2 to 35khz which seems to have solved the Y axis stalling, changed the driver board for the A axis and has reduced the stalling for X.

I am now able to air cut between 72 - 110ipm but now where it used to sound good cutting at 60ipm it sounds rough and sometimes stalls, i'm not sure if this is mid band or low band resonance? it sounds fine between 30 and 50ipm but inbetween say 52 to 70ipm it sounds rough.

I have found that when most of the stalling occurs it is moving X and another axis, thats why I bumped it up to 35khz thinking it wasn't putting out enough steps to the drives although my calculations place it at about 19,000 pulses per drive .
Thanks for the help.

Robert

[ger21]

I believe that only the 2Ghz machine is fast enough to run at 35Khz.

Are you using shielded cable for the motors?

[orbyog]

After rereading the Mach2 manual it stats to use 35khz on cpu's 1ghz or higher .... it does run fine at about 36,126hz.

Yes ALL (motors, limit, & home) cables are run 18gauge shieled.

I've been changing the acceleration a bit, what is the optimal setting? high as possible or more of a curve? the manual says what ever sounds good , I had thought running 60ipm sounded good untill I heard how it sounded at 90ipm (without stalling).