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Author Topic: 4 axis feedrate coordination  (Read 13129 times)

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Re: 4 axis feedrate coordination
« Reply #20 on: January 25, 2014, 04:14:43 PM »
Mirco,
if you put in 10.000 as you said, that's only 1G  you need at least 5G ( 50.000) to see a reasonable different. I tested with 10G ( 100.000 )
Whether it will work or not depends on your A-Axis mechanism. ( what diameter, what mass, friction, transmission, transmission ratio, and motor)
At least  you can test it.
Alex
Re: 4 axis feedrate coordination
« Reply #21 on: January 25, 2014, 05:36:22 PM »
Alex,
I entered 100.000 but unfortunately the result is still the same.
Re: 4 axis feedrate coordination
« Reply #22 on: January 25, 2014, 07:26:06 PM »
Ad a G64 to your G-Code.
Alex
Re: 4 axis feedrate coordination
« Reply #23 on: January 25, 2014, 07:47:57 PM »
Added G64, still no difference.
Re: 4 axis feedrate coordination
« Reply #24 on: January 25, 2014, 08:18:23 PM »
Did you increase the feedrate to F8000 in your G-Code ?
Alex

Offline simpson36

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Re: 4 axis feedrate coordination
« Reply #25 on: January 26, 2014, 06:35:46 AM »

 Mach will ignore everything else and calculate the correct 4th axis federate for a move using G93 (provided you have the bandwidth - rotary axis pulse rates can get very high in a hurry).   


I have never used G93, my CAM does not support it.

However I assume Mach will still honour the maximum velocity as set in motor tuning. (normal rapid speed)  If so, then why will pulse rates go beyond normal levels ?

Greolt

My comment about bandwidth was only to point out that Rotary axii require very high pulse rates compared to linear. So much so that often on first exposure, users think there is something wrong when actually the system (particularly if using a PP) is maxed out and the rotary axis is not 'spinning' as expected.
 
However, you raise an very good point about the set maximums being honored.  Clipping an excessive rate would have to come after the G93 calculation determines the rate, and I don't know if Mach does that or not. It is certainly a good question and one that should be answered/tested. I just moved my shop and my machines are down or I would have done that before posting back. Perhaps somebody can MDI a super fast G93 and post the result. It would be very good info to have.

I would think that the CAM software would specify the federate in the G93, so normally an 'overspeed' condition that would not be a problem.

To your specific question, I am not sure what you mean by 'normal' levels, but if you mean the global F setting, then yes, a G93 federate will go beyond. The F setting and all of the parameters that effect it (except probably accel) seem to be ignored when G93 is active.