Question Ridged Z Joints?

[jetcat]

Printer Model

Voron 2.4

Trying to figure out in my head how this works. QGL by bending the extrusions?

Rigid Fixed Z Joints for Voron

Description Rigid Z Joints help to minimize overall printer vibration providing better Input Shaper results. Compatible with printed gantry but perform the best with CNC gantry parts. Must have for chasing maximum performance. Machined from 6061 aluminium grade for the best rigidity and...

vitalii3d.com

 

[3dCase]

I would think this fixed Z joint will minimise and level out any sag, thus keeping the gantry mostly in one plane rather then flex. It is not bending anything and is much more rigid overall. I cannot confirm their statement but it sounds acceptable and logical at first glance. I use the chaoticlab all metal cnc parts but they do have some movement in the joints, albeit much less then the original printed version.

 

[jetcat]

I would think this fixed Z joint will minimise and level out any sag, thus keeping the gantry mostly in one plane rather then flex. It is not bending anything and is much more rigid overall. I cannot confirm their statement but it sounds acceptable and logical at first glance. I use the chaoticlab all metal cnc parts but they do have some movement in the joints, albeit much less then the original printed version.

Yes, I get there is advantages to the gantry being ridged but if the bed isn't perfectly parallel to the gantry, how do you adjust. I have spherical bearings and low profile Z joints made out of PC-GF but I can also do a qgl without bending anything. Just curious if anyone has any experience with a ridged Z joints. How would you synchronized the Z motors? The belts have enough elasticity?

 

[3dCase]

Elasticity in the belts would ne a bad thing.
And your bed is a plane, because the aluminium bed is cast and true. So as long as your gantry is also a plane, and not some torqued crisp shape, the QGL will find the correct level and nothing will bend or stretch.
If the bed has some shape issues, the bedmesh will take care off that without bending anything. The controler knows where is the toolhead so it raises and lowers the whole gantry to match the bedmesh values. Again no bending or stretching.
I think you are overthinking it a bit.
The plastic parts have low rigidity so the gantry can sag in one corner and is not a proper plane anymore. QGL takes care of this.
With more tigid z corner joints the gantry will not sag so easilly and will remain better in a plane so the QGL will have less work to do. Once leveled nothing moves out of sync, all 4 z motors become as one.

 

[jetcat]

Elasticity in the belts would ne a bad thing.
And your bed is a plane, because the aluminium bed is cast and true. So as long as your gantry is also a plane, and not some torqued crisp shape, the QGL will find the correct level and nothing will bend or stretch.
If the bed has some shape issues, the bedmesh will take care off that without bending anything. The controler knows where is the toolhead so it raises and lowers the whole gantry to match the bedmesh values. Again no bending or stretching.
I think you are overthinking it a bit.
The plastic parts have low rigidity so the gantry can sag in one corner and is not a proper plane anymore. QGL takes care of this.
With more tigid z corner joints the gantry will not sag so easilly and will remain better in a plane so the QGL will have less work to do. Once leveled nothing moves out of sync, all 4 z motors become as one.

Yes, I understand your explanation but you realize the ridged joints being sold have ZERO flexability. All 4 Z motors would be locked solid together making a qgl meaningless. At least that's how I'm seeing it unless that's the whole idea.

One thing, it would eliminate the rear grantry droop that plagues my V2.4 350......

 

[3dCase]

No your assumption is slightly off. It will still have some room to move up and down but it will fix the gantry in a plane onto itself. The flex which that will cause is from the rest of the frame and whatever little is in the gantry itself. No matter how stiff the gantry is, because of the uneven weight distribution dependend on where the toolhead is, as soon as the motors are switched off the gantry is free to fall a little. this means you must do a QGL again no matter how stiff the z-joints are. You cannot guarantee its position or its horizontal level anymore. The 4 z motors are never locked as one until you switch it back on and the motors are powered up. then you do a QGL and they will reset themselves after one two or three cycles into the right plane in level with the 4 corners of the bed. Once that is done they are truly locked as one.
p.s. zero flex does not exist and certainly not in a machine that relies on aluminium extrusions of only 2020! Even a cast iron lump of 4 tons making up the frame of a cnc machining centre has flex. Its all in proportion though, in comparison to the forces at play.