Bed skewed causes/fixes?
Though my printer said the calibration was "all right" and it will adjust for the skew, I want to fix it.
When you look down you can definitely see that the bed is not parallel to the X rods.
Now I know the manual states that in this case the solution is to adjust the nuts on the frame. I did that, but I don't like what it is doing to the z-axis aluminum frame.... it's warping/bending it...which makes sense. Since you're just adjusting one side and the side you are not is being held perpendicular to the rod, then as you push/pull the other side, it has to bend/warp the frame.
So this is telling me that the z frame is perpendicular to the y frame rods BEFORE I start adjusting. Plus I measured the distance from the y frame rods ends to the frame with digital calipers and they were both exactly 100mm.
All of this is to say that I don't think the y frame rods are the source of the issue. The bed is pretty far out of wack. So what other causes are there?
Re: Bed skewed causes/fixes?
Hi!
Just a beginner myself, but an adjument by one or two millimeters is not supposed to bend the frame! I remember I had plenty of "play" when I fit the y-frame to the vertical metal frame (the one with the PRUSA logo). Could it be that the fit is too tight? When you measure the distance between the smooth metal rods of the y-frame (the ones the heatbed slides on), it's supposed to measure EXACTLY 178mm, both on the front and back sides. I think it may not be in the manual text, but it's in one of the videos from that chapter. Apparently, even 178.5mm is wrong. This is a measurement of the rods' external sides' distance.
Please be careful, because even metal can be warped when tightening screws etc. I found this the hard way when attaching the PSU.
Best of luck! Panos
Re: Bed skewed causes/fixes?
Thanks for taking the time to reply Panos.
The fit of the z-frame (vertical one with PRUSA logo) into the y rods is not tight...they slip right in. My point was that in theory, you should be able to tighten up one side (one of the y rods to the z frame) and then let the other side of the frame float (to not have any pressure by the tightening bolts on either side of the z frame) and in that case, the z frame should be exactly perpendicular to the y rods. In reality, this may be off a tad, but it shouldn't be too far off, unless the z frame or the y rods are warped to some degree. Turns out, that is the case...the z frame is a bit warped, which is why I felt I was having to apply too much pressure to the other side's y rod adjusting nuts to get the bed perpendicular.
In this pic, note the gap on the right side of the straight edge and the z frame...its about 1/8"off.
I also found a better way to measure the perpendicular-ness during adjusting, but placing the straight edge on the frame instead of just eye balling the X rods...this worked out much better, and was way more accurate. Now the XYZ calibration result was perfect.
