In 2017, I was upgrading a router to a Centroid All-In-One controller. To test the machine, I used a file that is a maze of concentric circles. I've attached a PDF. In executing the file at 300 ipm, the machine's movement was anything but smooth. Scott Pratt at Centroid advised that my encoder resolution was too low. The servos had 1000 pr encoders. He recommended 5000 or 10,000 for large format routers. This machine had a 42" x 84" XY work area. I purchased 10,000 pr encoders and the problem was solved.
Now I'm to upgrading three large format industrial routers to Centroid.
First up was an SCM Tech99L pod and rail machining center. I put a Oak board in it to control its Yaskawa servos. The Y axis is 8192 pr and the X axis 4096 pr. The work area is 50" x 126". When executing the maze file, the movement resembled that of the previous upgrade, not smooth but with stutters at 2:00, 4:00, 8:00 and 10:00 when moving at 300 ipm. All other movement was good. The machine smoothly and effortlessly can execute G1X120Y48F2000. Could low encoder resolution be the problem here too or is it that the encoder count on X is half the count of Y.
Next is a 1999 Multicam Pro with a 60" x 144" work area and 2000 pr servos. Here, the original motion control is an Allen Bradly hybrid system with a Multicam M23 board sending step and direction signals to the servo drives. Here I unplugged the Multicam S and D commands and replaced them with ones from an Acorn board. After running the maze file, the movement was not ideal. Like the previous upgrades, there was vibration. Not as bad as the SCM. Different. The SCM had problems with large circular movement. The Multicam with small circles.
The Multicam is set up so I can switch back and forth between motion controllers until I work out all of the kinks. When I ran the same maze file on the original 1999 motion control system, it was very smooth. What about the step and direction signals would make the motion different? Is the low (2000 pr) encoder count the problem.
There is one difference in the step and direction signals between the systems. The Allen Bradley drives did not like the Acorn step and direction signals. They moved twice as fast in one direction as the opposite. We resolved this problem by converting the Acorns commands to differential signals. I now need to see how the irregular movement impacts cutting. This machine primarily cuts aluminum at a significantly slower feedrate than 300 ipm so it may not be a problem.
My next upgrade is a 2006 Flexicam router also with a 60" x 144" work area. It has Panasonic servos with 2500 pr encoders. My hope is that I can use an Acorn board to convert it to a hybrid servo system without upgrading the encoders. It all depends on whether 2500 pr is too a low a count and will result in irregular motion. This machine runs at 300 ipm all day. Clunky movement would be more of problem here.
Any advise would be greatly appreciated.