1800x1200 Gantry Vibrations
Posted: Sun May 28, 2017 7:13 pm
Hoping maybe someone has run into this issue. I have the big 1800x1200 XY and I have issues with squiggly lines during raster engraving anywhere in the middle 2/3's of the X axis. Maybe this is just a characteristic of such a large machine, but I am wondering if anyone has any ideas on how to eliminate it. Immensely slowing the machine down and/or using unilateralism will mostly cure it, but, the speed is needed.
I've tried removing my e-chain from the gantry, adjusting belts, adjusting rollers, but none of it gets rid of the issue. The X axis beam is just not rigid enough to avoid flexing due to its size. It's almost like it needs a truss on the back side of it to make it more rigid. If I cut something small right at either extreme end, it's fine. That's just not usable for production as just about everything is bigger than that little area.
In real use it's not extremely obvious as most things we do have decently large engraved areas or such a small scan gap that the gantry doesn't accelerate enough to cause a problem. If I do a test run with a scan gap of 0.75, my return swing on x-swing raster will be so wavy that it almost touches the raster line above and below at the edges of the engraving where the gantry is stopping and reverberating. It'll get more exaggerated as it progresses and shakes more.
I realize at this point that such a large machine is probably best suited to large cutting jobs only and we may need something smaller for precise small cuts. 100W tube in this machine coupled with this issue means I couldn't dream of cutting card stock or paper since it'll just annihilate it if i go slow enough to eliminate the wavy lines. Sort of like using a sledgehammer to drive a brad nail. Just wish I had known before building it, but, you live and learn.
If i'm missing something, let me know! I'm open to suggestions. I've played around with all sorts of accel and jerk values. I do have to play with X backlash a bit to clear up x-swing engravings. Just a lot of mass and belt length to deal with.
I've tried removing my e-chain from the gantry, adjusting belts, adjusting rollers, but none of it gets rid of the issue. The X axis beam is just not rigid enough to avoid flexing due to its size. It's almost like it needs a truss on the back side of it to make it more rigid. If I cut something small right at either extreme end, it's fine. That's just not usable for production as just about everything is bigger than that little area.
In real use it's not extremely obvious as most things we do have decently large engraved areas or such a small scan gap that the gantry doesn't accelerate enough to cause a problem. If I do a test run with a scan gap of 0.75, my return swing on x-swing raster will be so wavy that it almost touches the raster line above and below at the edges of the engraving where the gantry is stopping and reverberating. It'll get more exaggerated as it progresses and shakes more.
I realize at this point that such a large machine is probably best suited to large cutting jobs only and we may need something smaller for precise small cuts. 100W tube in this machine coupled with this issue means I couldn't dream of cutting card stock or paper since it'll just annihilate it if i go slow enough to eliminate the wavy lines. Sort of like using a sledgehammer to drive a brad nail. Just wish I had known before building it, but, you live and learn.
If i'm missing something, let me know! I'm open to suggestions. I've played around with all sorts of accel and jerk values. I do have to play with X backlash a bit to clear up x-swing engravings. Just a lot of mass and belt length to deal with.