Yet another thread about gantry squaring

[Ranayna]

Printer Model

v 2.4

Hi,

i am in the process of building a V2.4, the LDO Motors Kit, with CNC Parts from Chaoticlabs.
So far, i am impressed with the quality and especially the documentation.

But i hit a snag when i try to square the gantry. I suspect what the issue is, but i would like confirmation before i undo everything

While the gantry is freely hanging on the belts, i can easily square it. After having done that, when i reattach the z carriages, the last one does not fit as smoothly as the other three, and once that one is in, the gantry is not squared anymore. It is out by maybe two millimeters on two opposing corners.
The same happens when i try to square the gantry with the carriages attached.

Am i correct with my assumption that the frame itself is not properly square then? It does not wobble at all, but when i undo the screws on just one corner, the profiles move.

 

[NoGuru]

Z axis should have nothing to do with squaring the gantry. Finish the Z axis setup a you won't need to start racking until you get to the point of tightening the idlers.
Don't spin one idler all the way then do the other, do them as equal as possible. I do this by doing like one turn at a time on each idler.

 

[Ranayna]

So, i went ahead and redid the frame anyway.
And it turned out that my workbench was not as flat as i tought. I also noticed, with a bright light in the background to see the edges of the profiles better, that the profiles move quite a bit when tightening the screws. I was careless on the first go and did not properly check the corners during and after tightening.
So i went along all corners and redid the frame completely. Did not take as long as i was afraid, with all sub assemblies done and the t-nuts in place, it was back together quite quickly.
I think my frame is better now, but i did not yet have the time to put the belts back on, which i will do tomorrow.

 

[Dave32]

Z axis should have nothing to do with squaring the gantry. Finish the Z axis setup a you won't need to start racking until you get to the point of tightening the idlers.
Don't spin one idler all the way then do the other, do them as equal as possible. I do this by doing like one turn at a time on each idler.

I presume they are following the Ellis guide:

Voron V2 Gantry Squaring

Ellis’ Print Tuning Guide

ellis3dp.com

and are on Step 9, at the part where you drop and raise the Z-axis carriages to check that the gantry frame above it is aligned?

If so, this would be without any tension at all on the idlers... belts loose... before the de-racking steps.

 

[Ranayna]

No, i am not following this guide, although i have read that already.

I am still in the process of building the printer, and am on page 122 of the manual, after attaching the joints and adding the 4 Z belts, the manual tells me to "square the gantry" by moving it to the back. And there i notice that it does not hit both corners at the same time. The same if i move it to the front, but the opposite corner. If i push and then tighen all screws, it still moves back when i release it.
So it's clear that the gantry is not properly squared.
By this time, even with the idlers loose, i had quite a bit of tension on the belts. Maybe too much? The manual is not clear how tight i need to have the belts with the idlers still loose.
I still need to reattach the belts, maybe i will try to loosen them by one notch.

EDIT: Now i feel stupid
After belting, the problem was still there, just as before. I re-read the manual, also re-read Ellis' guide, and then i noticed that idiot me did not loosen the screws of the bridge
After undoing those just a bit i was able to adjust the angle of the bridge, now it is hitting both sides at the same time.
Well, it seems square enough now to continue with the assembly.

 

[Dave32]

By this time, even with the idlers loose, i had quite a bit of tension on the belts. Maybe too much? The manual is not clear how tight i need to have the belts with the idlers still loose.
I still need to reattach the belts, maybe i will try to loosen them by one notch.

Oh yeah, I had trouble with this too. I actually think that section of the manual should be revised, as it sends people down a problematic path.
Specifically, page 141 says

PULL TIGHT - Grab both belt ends with a pair of pliers and pull the belt tight.

However, if you do this, there isn't enough slack in the tensioners to fully release the belts enough for the gantry squaring process later on.

Instead, a better recommendation would be to take the slack out but not use tools or overly tighten the belts. Then have the "use pliers / pull tight" process be something that is done *after* the squaring process has been completed.

 

[falkien]

Hi,

i am in the process of building a V2.4, the LDO Motors Kit, with CNC Parts from Chaoticlabs.
So far, i am impressed with the quality and especially the documentation.

But i hit a snag when i try to square the gantry. I suspect what the issue is, but i would like confirmation before i undo everything

While the gantry is freely hanging on the belts, i can easily square it. After having done that, when i reattach the z carriages, the last one does not fit as smoothly as the other three, and once that one is in, the gantry is not squared anymore. It is out by maybe two millimeters on two opposing corners.
The same happens when i try to square the gantry with the carriages attached.

Am i correct with my assumption that the frame itself is not properly square then? It does not wobble at all, but when i undo the screws on just one corner, the profiles move.

I highly suggest these

Z Locks by tallman5

Helping hands curing v2.4 build, replaces long zip ties.

mods.vorondesign.com

 

[Ranayna]

I considered the Z Locks, but for now i don't need them anymore.
All the belting is done now, the gantry feels reasonably squared, finer adjustments will be done once the electronics are finished.

My next step is the Stealthburner.