Mike Package
12-09-2010, 9:24 AM
I posted this over at Camheads but I'm not sure that everybody who posts here posts there and I wouldn't mind hearing from other CNC'ers in general.
http://www.camheads.org/showthread.php?t=628
In a nutshell I'm experiencing a problem with my Stinger I with cuts - the problem is most readily visible when cutting circles, moreso at one end of the X travel than the other. Looking at the attached photo, the cut starts at 12:00. When X starts to change direction at 3:00, it reveals the first hiccup. It looks like X doesn't engage at the right time so the curve is off. Then the same thing happens at 9:00 when X is changing direction again.
The first area I looked at was play in the X axis between the rack and the gear. Grabbing the gantry and moving it by hand along X revealed a bit of play. I lowered the rack closer to the gears and also tightened the motor belt, which seemed a bit looser than the others. These adjustments made a noticeable improvement. But things are still not quite perfect and the quality of cut varies along X. Circles towards X0 are worse than circles out at the other end of X, etc.
I can still feel a tiny bit of play in X. I'm left with a handful of questions that I'd like to throw out to the group...
Is anybody else experiencing a similar issue?
I can still feel a tiny bit of play when moving X by hand, say <1/32". Is that out of the ordinary? Should it be completely immobile?
I'm finding adjusting the rack to be a difficult process. How can you tell when you're tight enough? Too tight?
If the rack and belt are tight enough, can there be play elsewhere, like in the motor itself?
What other aspects could be involved besides the X mechanism? I don't want to completely rule out a software issue as a possibility yet, but it seems like the fact that the problem performing the same cut varies depending where you are along X would pretty much rule that out.
How perfect can I expect the results to be? I know that the attached photo of a bad circle is unacceptable. What would you consider to be acceptable? With my CNC Shark, I could cut circles that were basically indistinguishable from the same hole drilled on my drill press. That's the result I'm looking for. Is that asking too much?
Thanks in advance for any and all knowledge...
-Mike
http://www.camheads.org/showthread.php?t=628
In a nutshell I'm experiencing a problem with my Stinger I with cuts - the problem is most readily visible when cutting circles, moreso at one end of the X travel than the other. Looking at the attached photo, the cut starts at 12:00. When X starts to change direction at 3:00, it reveals the first hiccup. It looks like X doesn't engage at the right time so the curve is off. Then the same thing happens at 9:00 when X is changing direction again.
The first area I looked at was play in the X axis between the rack and the gear. Grabbing the gantry and moving it by hand along X revealed a bit of play. I lowered the rack closer to the gears and also tightened the motor belt, which seemed a bit looser than the others. These adjustments made a noticeable improvement. But things are still not quite perfect and the quality of cut varies along X. Circles towards X0 are worse than circles out at the other end of X, etc.
I can still feel a tiny bit of play in X. I'm left with a handful of questions that I'd like to throw out to the group...
Is anybody else experiencing a similar issue?
I can still feel a tiny bit of play when moving X by hand, say <1/32". Is that out of the ordinary? Should it be completely immobile?
I'm finding adjusting the rack to be a difficult process. How can you tell when you're tight enough? Too tight?
If the rack and belt are tight enough, can there be play elsewhere, like in the motor itself?
What other aspects could be involved besides the X mechanism? I don't want to completely rule out a software issue as a possibility yet, but it seems like the fact that the problem performing the same cut varies depending where you are along X would pretty much rule that out.
How perfect can I expect the results to be? I know that the attached photo of a bad circle is unacceptable. What would you consider to be acceptable? With my CNC Shark, I could cut circles that were basically indistinguishable from the same hole drilled on my drill press. That's the result I'm looking for. Is that asking too much?
Thanks in advance for any and all knowledge...
-Mike