Curiosity about squaring various i3 y-frames to the z frame.

On the normal i3 and variants that use threaded rods for the Y axis frame, how hard is it to get things squared?

I have a wilson variant and it's all determined by the cut of the aluminum extrusions and the mounting brackets which I can easily square off the extruded aluminum to make sure the Z frame is squared to the Y body. But I have always been curious how hard it is to square the threaded rods. It seems like you would have to keep loosening and tightening to the Z frame until you got it correct. Then I wouldn't even know how to tell it's square.

On the other hand, the p3 steel seems to be the easiest to square since it is the laser cutting that dictates how it fits together.

Edited 1 time(s). Last edit at 05/21/2015 03:06PM by milkypostman.

I don't understand the question completely, but I don't think you need to square the Y with the Z. If the Y frame is flat on the table, and the Z frame is perpendicular to the table, they're going to be more or less square. I would think that any deviation would be corrected by bed leveling, "Leveling" really means that the nozzle has a constant distance from the bed at all points, which is what's important.

But I'm just getting started and setting up my first printer, so I'm speaking more from logic than experience...

i guess I mean that the bed needs to go in and out perpendicular to the Z frame. That is, the frame cannot be twisted relative to the z frame or a square will end up like a parallelogram.

if you look at the prusa i3, it's two nuts tightened against each other that determines this and it seems like that would be a hard thing to square up.

But aren't you saying that you can easily square the Z frame with the Y frame? Doesn't that mean the bed will move in and out perpendicular to the Z frame? Maybe I still don't understand.

I had to assemble and disassamble my frame a few times now and worked up a method to align the 3 axes:

Let´s assume the y-frame is not twisted and the screws were tightened on a flat surface with all four corner blocks on the ground.

Now insert the y-frame in the notches of the ( acrylic ) frame but only tighten one of the four screws. ( say the rear left )
Then measure the distance from the left z-stepper ( e.g. one of the mounting screws ) to the left front-end of the y-tables smooth rod.
Do that on the other side as well and align the y-carrier until both numbers match.
Now tighten the other three screws and check the measurement again.
If it´s the same, you have successfully aligned x- and y-axis

Check if the 4 corner blocks and the z-frame are still flat to the ground.
Now you should have an adjusted frame
-Olaf

yeah that makes sense about the y frame itself not being twisted. yeah I can see now why the P3Steel would be quite nice though. I am very happy with the extruded aluminum of the wilson as well.

When I built my I3V, I had my square out all the time. What helped was having a large FLAT area to build it and some weights to keep it flat when I did the tightenings. As much as the engineer in me would want the unit to cut sharp edge 90 degree turns when printing, I have to accept that this unit cost me 3 figures and not in the 5-6 figure range. The squareness of the frame ensures smooth, nonbinding operation and undue stress to the machine,

Out of concern about the i3 design I decided to build the frame with MDF, and the z axis is firmly attached to a baseboard that sits under the entire printer. All biscuit jointed and glued, it's not moving.

Must have got something right, it has been moved several times and I have not yet had to recalibrate the built plate to z axis height. The heated build plate is also mounted rigid, to the carriage with no requirement for levelling springs.