I have built several FDM printers using the COREXY motion system with good success.
I recently decided to try and improve print quality where motion induced artifacts were visible.
I used a typical test cube with letters X Y Z on the sides and top to evaluate improvements (available on Thingiverse).
In looking closer I noticed that a ringing artifact that happened during Y movement was not symmetrical - it was more pronounced on the Y- side of an object.
This seemed very odd until I realized that generally speaking, COREXY construction is not symmetrical.
[attachment 114537 corexy_classic.jpg]
In a typical COREXY system there are two mirrored belt paths that occupy different levels so they don't conflict. The stepper motor that drives the belt is placed at one end of the belt path so that the motor drives very unequal lengths of belt depending on the direction of motion.
GT2 rubber belts stretch and resonate depending on length and tension which can cause some amount of motion induced 'ringing'. So could the unequal belt length be the cause of my anomaly?
To test this theory I modified a COREXY machine such that the stepper motors were very close to the middle of the belt path. You can see how that is done in this image:
[attachment 114538 corexy_belt_system.jpg]
After reprinting the test objects I can see that the asymmetry has been eliminated or dramatically reduced.
This does not improve motion induced artifacts but the asymmetry was not a good thing and I think it is a positive improvement for COREXY mechanics.
I would be very interested to hear your opinions or comments on this subject. Thanks
I recently decided to try and improve print quality where motion induced artifacts were visible.
I used a typical test cube with letters X Y Z on the sides and top to evaluate improvements (available on Thingiverse).
In looking closer I noticed that a ringing artifact that happened during Y movement was not symmetrical - it was more pronounced on the Y- side of an object.
This seemed very odd until I realized that generally speaking, COREXY construction is not symmetrical.
[attachment 114537 corexy_classic.jpg]
In a typical COREXY system there are two mirrored belt paths that occupy different levels so they don't conflict. The stepper motor that drives the belt is placed at one end of the belt path so that the motor drives very unequal lengths of belt depending on the direction of motion.
GT2 rubber belts stretch and resonate depending on length and tension which can cause some amount of motion induced 'ringing'. So could the unequal belt length be the cause of my anomaly?
To test this theory I modified a COREXY machine such that the stepper motors were very close to the middle of the belt path. You can see how that is done in this image:
[attachment 114538 corexy_belt_system.jpg]
After reprinting the test objects I can see that the asymmetry has been eliminated or dramatically reduced.
This does not improve motion induced artifacts but the asymmetry was not a good thing and I think it is a positive improvement for COREXY mechanics.
I would be very interested to hear your opinions or comments on this subject. Thanks
