Doug_Ford
Sun 03 February 2008, 14:04
I finally got around to doing some rapid traverse tests today. My machine has Vampire Geckos, PK296A2A-SG7.2 motors wired half coil with 35 tooth pinions.
I started with the pulse rate set at 35,000. From a dead stop, she traveled six feet in an average of 5.825 seconds which is 12.36 inches per second. Then I increased the pulse rate to 45,000 and retuned the motors. Under the same conditions, she averaged 4.64 seconds which is 15.51 inches per second.
Something strange happened during the tests though. Sometimes, she would travel 66 inches and then lock up. If she didn't lock up on the first pass, then on the return pass, she would lock up in the first 6-12 inches. I gradually slowed the acceleration rate down and when I reached 25, she quit locking up. Now, I wish I had waited to special order the gantry tubes in a thinner wall size. I used 1/8 inch.
I traversed at least a dozen more times without a lockup. However, I refuse to believe that it was still accelerating after 66 inches and I'm wondering if she was binding up or something. I haven't had a chance to set the Y axis square to the X axis and when I turn her on she clunks so maybe I need to drop the motor and spin the pinion until she starts more smoothly. Maybe the clunk gets her out of square and creates a high torque condition. Maybe the rails are slightly wider at the 66 inch point on my machine and the additional torque required to drive the gantry assembly through that point is enough to stall the motors out. Anybody else have a theory?
I started with the pulse rate set at 35,000. From a dead stop, she traveled six feet in an average of 5.825 seconds which is 12.36 inches per second. Then I increased the pulse rate to 45,000 and retuned the motors. Under the same conditions, she averaged 4.64 seconds which is 15.51 inches per second.
Something strange happened during the tests though. Sometimes, she would travel 66 inches and then lock up. If she didn't lock up on the first pass, then on the return pass, she would lock up in the first 6-12 inches. I gradually slowed the acceleration rate down and when I reached 25, she quit locking up. Now, I wish I had waited to special order the gantry tubes in a thinner wall size. I used 1/8 inch.
I traversed at least a dozen more times without a lockup. However, I refuse to believe that it was still accelerating after 66 inches and I'm wondering if she was binding up or something. I haven't had a chance to set the Y axis square to the X axis and when I turn her on she clunks so maybe I need to drop the motor and spin the pinion until she starts more smoothly. Maybe the clunk gets her out of square and creates a high torque condition. Maybe the rails are slightly wider at the 66 inch point on my machine and the additional torque required to drive the gantry assembly through that point is enough to stall the motors out. Anybody else have a theory?