Help with adjusting belt tension
After doing the "Z-axis mod" to make the bed more level I thought it was a good idea to have a look at the belt tension as I have found a slight gap (from factory) on the left side of the gantry. This turned out to be more work than I had anticipated.
I have followed the guide and tried different ways to solve this but I cant figure out how to do this properly.
https://help.prusa3d.com/article/adjusting-belt-tension-core-one-l-core-one_845048
The gantry alignment
Okay, so I have followed the steps outlined in the "Quick gantry alignment" section which seems to be another approach compared to what is described in the parent "Alignment" section: "Loosen the bolt on the corner with play less than the other." where i have loosened it completely as suggested in the quick version.
Anyway, I bent it into shape. I think... because its unclear how to test this. So far I have put the nextruder in the middle of the gantry and then gently pushed the gantry (pushing it as centered as possible) towards the tensioners looking for gaps. First I tried to make sure it was even by pushing the left side against the tensioner and a gap showed up on the other side. Doing the same thing on the right side caused a gap at the left side. Someone in the comments on the support/guide page had the same problem which then was advised by another commenter to tighten the belts somewhat. But I question that method because tightening the belts ever so slightly can possibly at this point have the undesired side effect that with the help of the belts straighten the gantry. The gantry is somewhat flimsy by design (nothing wrong here, just an observation) so I assume that some play is to be expected?
Keeping the gantry square
When it comes to the initial tightening of the belts to keep the gantry square, how should I know how much I have to tighten the bolts? There are no visible indicators. Should I just keep turning the bolts gradually and hope for the best? I've tried to use some reference guides in an attempt to make the tensioners equally loose and from that gradually tightening them as described. Problem is that the left one will become tighter sooner than the right one causing an uneven tension on the gantry. I've seen some people suggesting that you should then only continue with the right one so that the gantry is square and rely on the tuning later on.
Belt tension
Im using the "Belt tuning wizard" and I wonder how to accurately perform this test? If the top belt starts swinging at 88Hz I can keep it going up to 96Hz and at 96.5Hz it stops. Going backwards, from lets say 98Hz and down to 96Hz it will not start swinging until i reach a lower frequency, lets say 93Hz.
This made me stop the belt (by holding it still with a finger and then letting go) at each increment and let the belt start swinging by itself without the help of the previous frequency to find out the lowest and highest Hz. This narrowed the frequency range and somewhere in this range there will be a frequency that moves the belt the most...
But what to do when the belt moves about the same at lets say 92Hz as it does at 94Hz?
Am I doing something wrong here? What would the correct procedure be?
According to the guide "On CORE One L, the ideal target frequency range is a maximum of 95 Hz for the upper belt and a minimum of 85 Hz for the lower belt."
What does this mean? Anything between 85-95Hz is good enough for both belts?
Why then is the wizard so picky about some frequencies but not others? Sometimes it says "within range, nothing to do" and sometimes it wants me to adjust the tension even though both belts are within range? What am I missing?
For the core one 96Hz is optimal for the upper belt and for the lower belt it is 92Hz. There doesnt seem to be an equivalent for the Core One L.
Sorry for all the questions but I really want to understand this.
RE: Help with adjusting belt tension
Keeping the gantry square
When it comes to the initial tightening of the belts to keep the gantry square, how should I know how much I have to tighten the bolts? There are no visible indicators. Should I just keep turning the bolts gradually and hope for the best? I've tried to use some reference guides in an attempt to make the tensioners equally loose and from that gradually tightening them as described. Problem is that the left one will become tighter sooner than the right one causing an uneven tension on the gantry. I've seen some people suggesting that you should then only continue with the right one so that the gantry is square and rely on the tuning later on.
The key point is to never turn the 2 tension screws independently of each other. They must always be turned by the same amount in the same direction. After squaring the gantry with the belts completely slack, turn the left screw a few turns then the right screw a few turns. Put a mark on the screwdriver handle or if using an L-shaped hex wrench, use that as a marker. When the belts start to tighten, then back off using just one turn (360°), then 1/2 turn etc. Don't force the belts to get into range by turning independently or you can bend the gantry.
RE: Help with adjusting belt tension
The key point is to never turn the 2 tension screws independently of each other. They must always be turned by the same amount in the same direction. After squaring the gantry with the belts completely slack, turn the left screw a few turns then the right screw a few turns. Put a mark on the screwdriver handle or if using an L-shaped hex wrench, use that as a marker. When the belts start to tighten, then back off using just one turn (360°), then 1/2 turn etc. Don't force the belts to get into range by turning independently or you can bend the gantry.
Thank you. I'll try this.
What about the tuning wizard, how exact does it have to be? As long as its somewhere between 85-95Hz its good enough?
RE: Help with adjusting belt tension
What about the tuning wizard, how exact does it have to be? As long as its somewhere between 85-95Hz its good enough?
You can set the tuner to 95hz for the top belt. Then while it is vibrating, turn the screws (again by equal amounts) until you see the top belt oscillating. Then switch to the lower belt. If you have done it correctly, the bottom belt should be 3-6 hz lower than the top.