My shop partner has a 4x4 plasma table built by delusional design. He's had it for about two years and makes personalized signs and all kinds of one off jobs. He came to me saying that he's having problems with tolerances on like parts cut at the same time. So we did a measurement test. Programmed 50 inches of movement in both X and y from home point. On the X rails one side reads 49 7/8 other side 50. Y travel on gantry 49 3/4. Wtf
Machine frame is a .125 wall square tubing welded with a water tray. Extruded aluminum rails on each side of metal frame with a v wheel bearings 4 on each side. Both sides are driven by a nema17 92oz. Stepper motor with cog pulley and a cogged belt.
Y is also belt driven but by one stepper motor same specs. Z axis has a stepper that controls a ballscrew. Has height control too. Runs a hyperthermia 45 and uses repetierhost for programming.
I do fab and machining once I get into the programming and software I can't help him. So we did the test and only one motor gave the right distance so I asked him to cut the test length in half. So it should go 25". I forgot exact numbers but they were all off. Y ALWAYS being constant 1/4 off. Now the X was only like 1/8 off. I had him do the test again at 10". Y was like 3/16 off now and X WAS IN A 1/16 of each other but still not at 10. So the measurements were getting alittle smaller with less movement of each axis but never the distance called out. And the variance of measurements from each side on the X travel.
So my questions are the program should tell the steppers how many steps to go right. So my/his problem would be either the program or system isn't givin proper voltage to motors?
Stepper motors are losing efficiency and not counting correctly?
Belts are fatigued or worn between teeth causing measurement error.
Some of my preliminary checking was putting a mag base on z carriage and run the y travel. Had .002 deviance in 50" travel. Was consistent on both planes. Same with X carriage to rails was within .003. We actually replaced all the wheels and bearings on machine as a maint. Thing. Belts visually look good their like a nylon with metal strand reinforcements. We did tension all the belts though. Another question I had was how does the machine link up both steppers of the X travel to be exact. I would think that each belt would need to be timed with each other and same exact tension on both. I'm use to a gear rack system so that got me suspicious. Any thoughts or tips would be appreciated!
Machine frame is a .125 wall square tubing welded with a water tray. Extruded aluminum rails on each side of metal frame with a v wheel bearings 4 on each side. Both sides are driven by a nema17 92oz. Stepper motor with cog pulley and a cogged belt.
Y is also belt driven but by one stepper motor same specs. Z axis has a stepper that controls a ballscrew. Has height control too. Runs a hyperthermia 45 and uses repetierhost for programming.
I do fab and machining once I get into the programming and software I can't help him. So we did the test and only one motor gave the right distance so I asked him to cut the test length in half. So it should go 25". I forgot exact numbers but they were all off. Y ALWAYS being constant 1/4 off. Now the X was only like 1/8 off. I had him do the test again at 10". Y was like 3/16 off now and X WAS IN A 1/16 of each other but still not at 10. So the measurements were getting alittle smaller with less movement of each axis but never the distance called out. And the variance of measurements from each side on the X travel.
So my questions are the program should tell the steppers how many steps to go right. So my/his problem would be either the program or system isn't givin proper voltage to motors?
Stepper motors are losing efficiency and not counting correctly?
Belts are fatigued or worn between teeth causing measurement error.
Some of my preliminary checking was putting a mag base on z carriage and run the y travel. Had .002 deviance in 50" travel. Was consistent on both planes. Same with X carriage to rails was within .003. We actually replaced all the wheels and bearings on machine as a maint. Thing. Belts visually look good their like a nylon with metal strand reinforcements. We did tension all the belts though. Another question I had was how does the machine link up both steppers of the X travel to be exact. I would think that each belt would need to be timed with each other and same exact tension on both. I'm use to a gear rack system so that got me suspicious. Any thoughts or tips would be appreciated!