Mach 3 Pausing after every arc and line while in CV mode?

[gavztheouch]

Hi,

A little back ground info on my machine....

I have a large Multicutter 8000, 3 axis router ( 3m * 4m ) bed size. The gantry weights around 700kg. Its rack & pinion x and y and a ball screw on the z.
Im using granite devices servos drives to drive the original 20 year old west amp servo motors. Everything is working well when the machine is running slowly, the problems arise when I crank up the feed speeds to anything above 1000 mm/min.

The problem: The motors stops for a split second after most arcs and lines, causing the heavy gantry to stutter and jerk. An example would be a circle made up of 4 arcs, after each quarter the motor will jerk as it moves onto the next line of g-code. Rapidly moving the gantry back and forward with the arrow keys on my keyboard does not cause any jerking or vibration, so it looks to be software based rather than a mechanical errors causing the roughness of movement.

Another example would be an arc made up of small lines for every line mach3 stops moving just enough to cause vibration and jerking.

I have CV mode engaged, I have also tried turning it off in mach using the g64 (or is it G68?) command to turn it back on when it starts the g-code.

In the config settings I have all the CV options turned off, CV Feedrate is also turned off, look ahead is set to 200 steps I have also tried increasing this to 1000 and everywhere inbetween with no luck.

An ideas and thoughts welcome

Gav

[ger21]

Do you have backlash comp enabled?

[gavztheouch]

Hi Gerry yes backlash enable has always been off. Just ran my circle test piece again @ 2000mm/min everything fine. @ 4000mm/min big jerk at two quadrants of the circle, always at the same spot.

[gavztheouch]

I may have found a solution to this?

To increase my feed speeds I was using the feed speed adjuster on the mach3 main page, to get 4000mm/min I was increasing the feed rate up to 200% of the rate in the gcode. For one reason or another this seems to be the cause of the juddering. Could this be right? Anyone else noticed this before?

[Bolomill]

I have the same problem since I change the conputer and lost the configuration. I try diferents motor configurations , with not much diference. stil got the jerk after every block.
Also need help.
Guillermo.

[Bolomill]

I finally solve my problem with Mach3 jerking at the end of every block. Change the computer and everything worked . The old computer was runing out of memory.

[ger21]

I may have found a solution to this?

To increase my feed speeds I was using the feed speed adjuster on the mach3 main page, to get 4000mm/min I was increasing the feed rate up to 200% of the rate in the gcode. For one reason or another this seems to be the cause of the juddering. Could this be right? Anyone else noticed this before?

Yes, it's a known issue.
Programming for 4m/min and running at 100% will run smoother than 2M/min at 200% override. It's best to not use more than 150% overrride.