I had a different problem. From the assembly the belt tensioners were way too loose so slight turning of the screws did nothing. First there is essential to tighten the crews until the belt begins to feel the pain - see the slight movement. Only at this time you can begin to calibrate the play and then tighten the belts via app. I had to position my phone with microphone very close to the belt to have some measurements, but it worked.
With both belts completely loose, pull the gantry full forward and make sure both ends touch the tensioner blocks. Apply opposing forces to the ends to adjust (bend) the rail support brackets to achieve this "no gap" condition. No gap is a must in order to pass the Y-axis self test. Using belt tension to close the gap results in mismatched belt tension or worse. Read other comments.
For those having issues aligning the XY gantry with the front of the printer while tensioning, here's something the manual isn't clear about:
Both belts affect the tension overall, i.e. if you increase tension on the top belt, the bottom one also tightens up, so if your gantry if out of alignment but your tension is correct, loosen the side that's hitting the front first, then tighten the side that has a gap the same amount. Keep repeating until the gantry sits flush on both sides, then recheck the tension on both belts and adjust by tightening both sides roughly evenly.
If you cannot get the gantry aligned, DO NOT USE the tensioners to pull it square. They will break. I repeat, THEY WILL BREAK.
I managed to cross thread the left tensioner and then the square nut started spinning in the printed tensioner part. I had to repair it with epoxy putty. Be careful and don't be a dummy like me.
If you pluck the belt and you get more then 105 Hz, your belts are too tight. Be very careful and loosen them up. Something else is wrong.
In my case, I had terminated the belt unevenly during initial routing. One of them had 8 or so teeth past the nextruder mount and the other was closer to 5. The number of teeth left on each belt was not equal, so my belt tension was always going to be unbalanced. Also, since I had too much engagement on one belt, there was too much tension even with the tensioners all the way loose.
Follow the belt routing instructions exactly as stated. It was a real pain to dissemble the Nextruder to fix the belts.
Also, if nothing else, these calibration steps should be done before putting on all the covers/plastics. Not sure why you would cover it all up when doing major disassembly and rework is still possible.
I also overthightened the left tensioner while trying to find the right frequency.
It feels like the square nut is rotating. The tensioner pulley is not moving in any direction and turning the screw feels snappy every 1/4 turn, no matter which direction.
Disassembling the tensioner (along with the door sensor) was PITA and now I can't even remove the tensioner pulley from the belt-tensioner-left, so I have to replace both.
Both belts affect the tension overall, i.e. if you increase tension on the top belt, the bottom one also tightens up, so if your gantry if out of alignment but your tension is correct, loosen the side that's hitting the front first, then tighten the side that has a gap the same amount. Keep repeating until the gantry sits flush on both sides, then recheck the tension on both belts and adjust by tightening both sides roughly evenly.
If you cannot get the gantry aligned, DO NOT USE the tensioners to pull it square. They will break. I repeat, THEY WILL BREAK.
I managed to cross thread the left tensioner and then the square nut started spinning in the printed tensioner part. I had to repair it with epoxy putty. Be careful and don't be a dummy like me.
If you pluck the belt and you get more then 105 Hz, your belts are too tight. Be very careful and loosen them up. Something else is wrong.
In my case, I had terminated the belt unevenly during initial routing. One of them had 8 or so teeth past the nextruder mount and the other was closer to 5. The number of teeth left on each belt was not equal, so my belt tension was always going to be unbalanced. Also, since I had too much engagement on one belt, there was too much tension even with the tensioners all the way loose.
Follow the belt routing instructions exactly as stated. It was a real pain to dissemble the Nextruder to fix the belts.
Also, if nothing else, these calibration steps should be done before putting on all the covers/plastics. Not sure why you would cover it all up when doing major disassembly and rework is still possible.
It feels like the square nut is rotating. The tensioner pulley is not moving in any direction and turning the screw feels snappy every 1/4 turn, no matter which direction.
Disassembling the tensioner (along with the door sensor) was PITA and now I can't even remove the tensioner pulley from the belt-tensioner-left, so I have to replace both.