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Please review my settings
« on: November 23, 2013, 03:26:35 PM »
Hey Gents,

Have my 30 x 36 XZero ViperXZ up and running and though I am pretty happy with its performance (just finished motor tuning with the demo version of Mach3) and before I spring for the full retail version, I was hoping a member or two can review my settings.

I have 270oz 6 wire Watai steppers wired for bi polar half coil, the drivers are the Wantai DQ542MA, generic DB25 BOB. I don't need any clarification on driver settings, I have that all sorted out and I am pretty sure I have my steps per all sorted out as the machine will accuratly move what ever units of measure I input (I am working in inches).

The settings in motor tuning that I would like an opion on are the Velocity/Accel/Hz/ and Step/Dir Pulse numbers (1 thru5).

First-with the Hz set at 35000Hz, it looks like I am limited to Velocities of around 500IPM. The steppers don't stall at 500, but to be safe I set them at 450IPM. This seems pretty quick to me, is there any reason on a table this size to go any faster?

Second-I have the accel set to 15 and I did get the steppers to stall at around 25 or 30. Is this also a fairly reasonable setting, or should one expect faster? Again, seems like a pretty smooth ramp up, but it would be nice to know if this is good or not.

Third-The direction and Step Pulse numbers housed in bottom right corner are set at 5. They were at 5 when I installed Mach, and I have never touched them. Any benefit to changing them or is this a "Don't fix if it aint broke" scenario.

Fourth-Last clarification (or opinion) is, I bumped my Hz setting up from the 25000 to 35000 to raise my velocity ceiling and Mach set the upper limit to 499 (as mention earlier, I set it at 450, and this works great), however, just out of curiousity, I bumped it up to 450000 and the steppers started running funny, basically they would move fast, then slow, then fast, then slow as they moved across the table. Is this just the computer reaching it's speed threshold? Thing is, I used the speed test utility that is included and it ran 100000Hz with no issue. The computer is a Win 7 running a 3.4ghz AMD Phenon Black Edition and kills the WEI test except for graphics (onboard). I moved the Hz upto the 100000 setting just to see what would happen and it seems to run fine, but the fact 45000 is a fail has scared me into staying at 35000.

Right now the machine runs very smoothly, accurately and reliably. Should I just move on to the full version of Mach and start making wood chips, or is there a setting I listed that might cause issues moving forward? Any input would be appreciated...

Offline ger21

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Re: Please review my settings
« Reply #1 on: November 23, 2013, 03:41:44 PM »
The drivertest.exe isn't really a valid test imo. If it runs fine at 35K but not 45K, then leave it at 35K.

I'd leave the pulse widths at 5us if it's running fine. Lowering them won't gain you anything, and may not run as well.

450ipm is pretty fast, especially with those rather small motors. By lowering the velocity, you may be able to increase the accel. This may be desirable when you start cutting parts. You'll most likely be running Mach3 in CV mode, and higher accelerations will allow the machine to follow the toolpaths more accurately around corners. However, if the accel is too high, you may run into issues with the machine rigidity, as high acceleration can cause rather violent direction changes.

Sounds like you have it set up pretty good. You just might want to play with the accel velocity numbers and find out what works best for the work you'll be doing.
Gerry

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http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
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Re: Please review my settings
« Reply #2 on: November 23, 2013, 09:48:18 PM »
Thanks for the quick reply ger21, many a google search has sent me to threads you have replied in and you have always been very helpful and informative.

Two more questions if I may? 95% of my cutting will be 3/4" particle board, other 5% will be MDF, thats why I thought the bi polar half coil would be a good option as speed would probably serve me better than power, was this a correct assumption?

Also, I have read a few posts about selecting CV mode, and I kind of get the just of it, but, considering my settings and the material I am cutting, should I be selecting this mode? I could fire up Mach and check for myself, but the garage is freezing cold right now (up in Canada Eh) but could you tell me, is CV mode selected by default or do I have to select myself?

Thanks in advance...

Offline ger21

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Re: Please review my settings
« Reply #3 on: November 23, 2013, 09:57:25 PM »
It's about -10°C here in Detroit right now.

The faster you go, the more power you need, so that's a hard question to answer. Since stepper motors lose torque as rpm's increase, you usually want more torque at higher rpm rather than more torque at lower rpm. The reason is that the available torque at high rpm's dictates the performance you'll see. So I guess the answer is yes.

Just about everyone uses CV mode all the time. Without it, Mach3 comes to a complete stop at each line of g-code, which gives terribly jerky movement and long cycle times. It's probably off by default, but can be enabled in Config > General Config.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html