RE: Help me get my core one printing! *assembly issue
Some questions: when there is no tension the belt wheels on the tensioners hold the gantry back a bit, so if I push the gantry forward it gets stopped by the wheel. If I add a bit of pressure, it will still hit the tension assembly. Is this normal or does it suggest something is wrong? When there is tension and the wheel is pulled back, this issue goes away since the wheel moves deeper into the assembly.
Yes, that is normal. Some users have unscrewed the tensioner block & idler wheel entirely, to fully relax the belts and give generous wiggle room for bending the gantry. That also gets the idlers out of the way when checking the gantry squareness. But if you want to check that the gantry is square, it does not necessarily have to touch the end stops in the front; you can also check whether it has the same distance on both sides. Measure the distance with calipers or, probably easier, insert some spacers of the same thickness on the left and right side and check that the gantry/spacers/end stops touch on both sides at once.
Finally: a question- is it possible to run the built in printer tension wizard without having first attached the nextruder etc.? I am speaking of just the belts attached to the belt holder. I think ensuring belts are properly set up would be much easeir if I could dial them in BEFORE attaching everything that I would need to remove.
In principle this should work. The belt vibration measured by the tension wizard is not an oscillation of the "mass + spring" system formed by the print head and the belt, but rather an oscillation of the belt only, where the print head acts as a stationary end point. So it should give the same results without the Nextruder mass attached.
I have some small doubts that maybe, without the inertia of the Nextruder, the print head is "not stationary enough" to let the motors reliably excite the belts. But I think it is worth a try to run the tuning wizard. If you see clear vibration maxima at all, they should be at the right frequency.
RE: Help me get my core one printing! *assembly issue
I finished my Core One assembly last week and was confused as to when to use the Belt tensioning wizard. Instructions basically tell you to use the Belt tuning (strobe) wizard before you do the 1st power up.... I couldn't see how it could work as the belts were so slack (as per the build sequence) the motors wouldn't have engaged the belt!
What I did was to print on my old Mk3 a Core One Belt Tension Gauge https://www.printables.com/model/1312851-prusa-core-one-belt-tension-gauge-new-v2-design and after ensuring that my gantry was square (very important), used the gauge to tension the Belts into the ballpark, then did the initial power up of the Core One, ran through the power on wizard, then did the Belt tension wizard (strobe) to fine tune it.
I had initially tried the Prusa frequency app but gave it away as a bad joke.
RE: Help me get my core one printing! *assembly issue
I finished my Core One assembly last week and was confused as to when to use the Belt tensioning wizard. Instructions basically tell you to use the Belt tuning (strobe) wizard before you do the 1st power up.... I couldn't see how it could work as the belts were so slack (as per the build sequence) the motors wouldn't have engaged the belt!
You have a point there. The instructions only mention the coarse manual tensioning of the belts in the yellow "Quick gantry alignment" box, which is supposedly only a fallback in case the gantry is skewed, not a part of the regular tension adjustment.
And they don't give any indication how much to tension the belts. So for a new user/builder of the Core One, getting them into the ballpark where the wizard can take over seems like a potshot. I think Prusa should include the printed tension gauge in the kit. It does not have to be exact, just get you into the 60..100 Hz range.
RE: Help me get my core one printing! *assembly issue
@soulbladeofdawn
Stay calm, no need to rush!
First, align the gantry mechanically with the belts loose!
Do not try to straighten it by tightening the belts!
Only once this step is complete, tighten the belts evenly and not too tightly!
Then proceed according to the assembly instructions, step by step...
RE: Help me get my core one printing! *assembly issue
As you begin to tighten the belts, you don't want to bend a straight gantry by tightening one too much. Thus, you go back and forth so the tension is built up evenly. Then, when you're close, you tighten or loosen one and one only to make the gantry perfectly straight, as it was at the beginning. The belts do not operate terribly tight to get the resonance in the right place. You can tell when you're close if it takes about 200 grams of force to push either belt into contact with the bearing rail.
I don't know if it's essential to have the Nextruder in place, but I'd certainly do it that way. If you want to know a bit more about belt tension, I wrote up some notes here https://conradhoffman.com/3d01.htm
Did you know that Gates actually makes a "Sonic Tension Meter" for their belts? Alas, you could buy three Core Ones for the price. OTOH, it would be less convenient than what we have, and the results wouldn't be a bit better.
RE:
An update: After spending an entire day with support, we were able to get the belt to tension within acceptable levels. Only the homing test failed. Support told me to adjust belt tension to square the gantry without worrying about tension levels. After this, homing was successful.
I was excited to possibly start my first print but then, z axis test failed. Support asked me to remove the nut (forget the name) that causes the plate to raise on of the 3 motor rods and then grease them. This did not fix the issue. Chat with support cut off and it was late so I ended up stopping there.
Current status: x and y are passing tests. Belt tension is likely off but this is allowing it to pass homing. Z axis functions and seems to function (loudly) and is currently an unresolved issue.