Messages

121

General Mach Discussion / Re: Steppers as spindle motors

« on: May 27, 2013, 08:55:45 PM »

The biggest problem you'll have is that steppers simple don't do high RPM, and their torque falls off much more quickly with increasing RPM than other types of motors.  The larger the stepper, the worse these characteristics become.  For large steppers, you may not get above 1000 RPM.

Regards,
Ray L.

122

General Mach Discussion / Re: need some help with a programming question

« on: May 24, 2013, 10:20:36 PM »

Mach3 seems to do coordinated moves for rapids, so I don't think it will be dog-legging (even though I believe, per the RS274 spec, it SHOULD run each axis at maximum speed).  That would for sure happen on some systems, and even with Mach3 with some motion controllers, however.  For example, KFlop.

Regards,
Ray L.

123

General Mach Discussion / Re: need some help with a programming question

« on: May 24, 2013, 08:29:05 PM »

You're also running the entire program as rapid moves, not feed moves.  I'm not sure rapid moves will be blended together - I believe they will always stop at the end of each segment.  You really should be using G1 instead of G0.

Regards,
Ray L.

124

General Mach Discussion / Re: Gecko 320x

« on: May 09, 2013, 09:21:14 AM »

hi,

yes it is, I use us digital, but what kind of resistor should I use? how many K?
thanks
Robhi

I don't recall the details, but there is documentation on the Gecko site detailing exactly what's necessary to make USDigital encoders work with the G320X.  Personally I'd just ditch them, and get CUIs - they're under $30 each, and have selectable resolution.  Mounting is identical.

Regards,
Ray L.

125

General Mach Discussion / Re: Gecko 320x

« on: May 09, 2013, 12:46:06 AM »

What kind of encoders are you using?  G320X's don't really like USDigital Encoders - you must add pullup resistors on A/B, and disable encoder failure detection.  They work very well with CUI encoders.

Regards,
Ray L.

126

General Mach Discussion / Re: Gecko 320x

« on: May 08, 2013, 09:14:33 PM »

Are Have you tried reversing the motor or encoder A/B wires?  If the motor is not in sync with the encoder, the Gecko will fault on power-up.  With all the pots at 10 o'clock, and no load on the motor, it should power up properly.  Do you have ERR/RES connected to ENC+?

Regards,
Ray L.

127

General Mach Discussion / Re: Gecko 320x

« on: May 08, 2013, 04:59:04 PM »

Where do you have the current limit pot set?  One of the minor details Gecko has never bothered to document is that the current limit pot works backwards from the old G320, and normal convention - fully CCW is max current.  I set mine up like the previous G320s, and got nothing but faults.  Had to talk to two different people at Gecko before they told me that pot was bass-ackwards.

Regards,
Ray L.

128

General Mach Discussion / Re: Losing Pulses at lower accelerations

« on: April 07, 2013, 03:57:38 PM »

You're barking up the wrong tree.  The Geckos couldn't care less about jitter in the step pulses.  The stepper motors care a LOT!  Jitter WILL cause lost steps, if not outright stalling.  Combine that with mid-band resonance, and everything you're seeing is as should be expected.  There is no benefit whatsoever to running the kernel frequency any higher than necessary to reach your target step rate.  Few systems will run reliably even at 45kHz kernel speed, and any jitter at these speeds will cause problems.  VERY few PCs can run at 100kHz.  The jitter is purely a function of Mach3 software-generated step timing.  If you want to run faster, get a hardware motion controller, like SmoothStepper, KFlop, Galil, etc.

Regards,
Ray L.

129

General Mach Discussion / Re: Arcs and cutter comp

« on: April 02, 2013, 10:55:18 PM »

tool is stationary as this is a BP knee mill.  Let me think about that in my dreams tonight. 

Which means pressing the RIGHT arrow key should move the table to the LEFT.

Regards,
Ray L.

130

General Mach Discussion / Re: Arcs and cutter comp

« on: April 02, 2013, 10:12:39 PM »

Teh tabels moves in teh driection of teh arrows on teh control pendant, so they are going in the right direction. 

That is actually incorrect.  In the world of CNC, all motion is defined in terms of direction of movement of the tool, NOT the table.  Clicking on a "right arrow" control should move the TOOL to the RIGHT relative to the workpiece, or move the table to the LEFT on a milling machine.  So, your machine is setup backwards.

Regards,
Ray L.