Are the wheels on the Y-Axis supposed to be tight enough that they grip the horizontal bar? I'm having issues with the layers of my prints shifting, sometimes significantly. I was having significant issues with layer shifting, but I tightened my wheels on the Y-Axis and the issue has lessened significantly (at least after the first few layers). Has anyone else had issues like this? I'm certain that my flex-plate is not shifting, as I put down a piece of tape underneath and marked the tape so I could check if the flex-plate moved (which it didn't).
Sometimes my Y-Axis will have trouble moving, and I'm not sure if the eccentric nuts are too tight, or if the belt is too tight, or what.
(P.S. I'm not having issues with the X-Axis moving too much or too little as the layers are only shifted in the Y-Direction.)
there should be no play in the carriage. with the printer off try to firmly twist the carriage. there should be no movement. also manually turning each wheel should move the carriage. if the carriage does not move or the wheel skips while turning the wheels it need to be tighter
I went through and re-tightened all of my screws on the gantry to make sure that none of the wheels were sliding. I've made sure the Y-Axis belt is very taught as well. I even tried increase and decreasing the current to the Y stepper driver by rotating the trimpot on the stepper driver.
The layers are still shifting, sometimes quite badly. Here's a picture just so you can see. It seems that my layers shift toward the front of my printer. Not sure why though.
Update: It seems that the two wheels attached to the eccentric nuts might be part of the problem. When spinning them by hand, they will usually move the gantry. Sometimes though, it's as if the gantry gets stuck, or the wheels become looser, as they will stop moving the gantry even though I can still spin them. I don't think tightening the bolts or the eccentric nuts is the answer (As I can't tighten the eccentric nuts any further) and the bolts are already pretty tight (and loosening them causes the gantry to wiggle).
Sometimes, when using the printer to move the Y-Axis, it will also have this same issue, it seems. It could be something else though. I'm not sure.
It's almost like there's too much static friction when the gantry first tries to move, and then I have to push it to make it actually move on it's own. Not always though.
Also, is it problem that my printer never prints in the Y center of my bed? It's always offset towards the back as you can see in the picture.
Do you have any suggestions?
reset the stepper trimpots to suggested positions before doing these adjustments.
i apologize for lack of clarity. by tightening the wheels i meant using the eccentric nuts. in the picture below they are the ones with the blue arrow pointing to them. turning them will increase/decrease the contact the wheels have with the gantry. you can us a 10mm wrench i believe. you may need to slightly loosen the screws and nyloc nuts, these should be just snug when making this adjustment. turn these nuts(either way doesn't matter). they offset the centerline of the wheels creating contact with the gantry beam. when checking the wheels to ensure proper contact. try pinching the wheels on the sides and rocking them. as pushing the wheel toward the gantry beam and rolling it with a single finger may give a false positive for proper contact. turning any one of the wheels should cause all the wheels to turn once everything is adjusted properly. once adjusted properly tighten the screws/nylocs. they should be just a little tighter than snug. too tight may cause issues with the bearings of the wheels.
the drive belt may be too tight. it should be tight enough to keep the belt from skipping but not so tight as to cause undue friction. loosen the tensioning roller at the end of the gantry. try sliding the carriage back and forth. be sure to continuously move it. you want to mimic the speed and change of directions the printer may do. stop if the belt skips. add some tension with the tensioner. repeat as necessary to stop the belt from skipping.
when you load a model into Cura it may not land centered. be sure to right click your object in Cura and selected center object before slicing to print. if this doesn't address the issue. there may be something in the firmware to adjust the offset. but that is outside my realm of expertise.
Oops, I was using the wrong word too. I meant eccentric nut everywhere I put nylock :)
if you are sure the eccentric nuts are to full offset toward the beam. and the wheels continue to slip. then the holes on the carriage bracket may be off. or unlikely but possible, the gantry beam is out of tolerances. you can easily check the gantry beam with a tape measure, ruler, or square. it should be 20mm, 2cm or just over 3/4". check it at multiple points along the beam. you could try rotating the beam 90 degrees if the tolerances are off. mine grips the beam well before the cam on the eccentric nut reaches full offset though. so i would guess the issue is most likely the holes in the carriage bracket. the centers on my screw heads are right just under an 1 11/16" or slightly under 41.5mm. thats a vertical measurement. from lower screw to upper screw. i verified it on the nyloc nut side of the screws. if you can't achieve this measurement by turning the eccentric nuts. then there again the bracket is the likely culprit.
if this is the case. request a replacement part. here is a link to the PDF for the Tool Carriage with all dimensions. for this or any other pieces its in the Downloads sections under Open Source Documents
I had some issues with the metal arms between the two spacer bolts not being perfectly straight. This caused them to grind along the 2020 rail when I had the wheels tightened to stop the wiggle on the tool carriage. I took a pair of pliers and straightened them out a bit and now there's no resistance, and my tool carriage seems straighter.
Here’s that link I meant to post in my above post. You can also find it By selecting Resources at the top of the page here. Then select Downloads. Then Open Source Documents, then Metal Parts. Once there scroll down to Tool Carriage