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General Mach Discussion / Not getting the desired cutting speed
« on: January 18, 2011, 05:16:11 PM »
Hi to all,
I have built my own cnc router about 3 years ago, as most of you guys did on this forum and have a small setback that
has been bothering me for a while, so I was wondering if anyone on the forum has ever come across this one. My cnc
router runs perfectly fine in all aspects when running at a cutting speed below 28mm/sec. As soon as I take it up to
say 50 or 60mm/sec, my cutting path gets messed up.
My current configuration / setup is as follows:
1 - PC Pentium4 core II 2
2 - Servo drivers from Rutex R990 type
3 - running software Mach3 at max clock speed on OS WinXP
4 - encoders on servos 500ppr
5 - cnc structure mild steel
6 - driver motors - servos rated at 6000rpm at 60V and supply voltage 58V DC (As seen here
http://www.servosystems.com/electrocraft_dcbrush_rdm103.htm )
7 - gantry driven by belt and pulley at a step down ratio of 4:1
8 - Using ball screws 10 travel per rev and gantry sliding on brass bushings
9 - working area 750mm x 550mm x 250mm
Now the problem is that when running at "higher cutting speed" the cutting path seems to initially loose orientation
but then comes back to the right path as can be seen in the attached photos showing "V" gap between cutting path. According to my calculations I should
be running at least 200mm/sec.
I have thought the following but could not figure out what could be wrong:
1- There doesn't seem to be any lagging between the gantry and the signal from the driver cards cause the gantry
starts going back a short distance clearly indicating it's way out of line.
2- I have tried a higher encoder resolution - no improvement
3- running mach3 at a lower clock speed - no improvement
4- checked servo actual running voltage - OK
5- Changed servo bearing the whole gantry movement to a more powerful one (type
http://www.kelinginc.net/KL34-170-90.pdf ) but running at voltage of 58V DC.
That's as far I have gone but to no avail and the only against me is the weight of the gantry which is about 20Kg
but nothing the motors cant handle.
Any comments please.
Thanks
marting
I have built my own cnc router about 3 years ago, as most of you guys did on this forum and have a small setback that
has been bothering me for a while, so I was wondering if anyone on the forum has ever come across this one. My cnc
router runs perfectly fine in all aspects when running at a cutting speed below 28mm/sec. As soon as I take it up to
say 50 or 60mm/sec, my cutting path gets messed up.
My current configuration / setup is as follows:
1 - PC Pentium4 core II 2
2 - Servo drivers from Rutex R990 type
3 - running software Mach3 at max clock speed on OS WinXP
4 - encoders on servos 500ppr
5 - cnc structure mild steel
6 - driver motors - servos rated at 6000rpm at 60V and supply voltage 58V DC (As seen here
http://www.servosystems.com/electrocraft_dcbrush_rdm103.htm )
7 - gantry driven by belt and pulley at a step down ratio of 4:1
8 - Using ball screws 10 travel per rev and gantry sliding on brass bushings
9 - working area 750mm x 550mm x 250mm
Now the problem is that when running at "higher cutting speed" the cutting path seems to initially loose orientation
but then comes back to the right path as can be seen in the attached photos showing "V" gap between cutting path. According to my calculations I should
be running at least 200mm/sec.
I have thought the following but could not figure out what could be wrong:
1- There doesn't seem to be any lagging between the gantry and the signal from the driver cards cause the gantry
starts going back a short distance clearly indicating it's way out of line.
2- I have tried a higher encoder resolution - no improvement
3- running mach3 at a lower clock speed - no improvement
4- checked servo actual running voltage - OK
5- Changed servo bearing the whole gantry movement to a more powerful one (type
http://www.kelinginc.net/KL34-170-90.pdf ) but running at voltage of 58V DC.
That's as far I have gone but to no avail and the only against me is the weight of the gantry which is about 20Kg
but nothing the motors cant handle.
Any comments please.
Thanks
marting