I am “finishing” my LR4 build, but I am encountering an issue that I just dont understand…I am sure you can help me
Everything was fine with the temp strut plates. Now I have cut the final ones out of 5mm MDF and I even confirmed that the measurements exactly match the DXF. However, it feels like the Xmin YZ plate is standing at an angle, i.e. the bottom is further out than the top attached to the beam. I noticed it when after attaching the wood struts it ran into the Ymin block when homing, which it previously cleared without issue. The Xmax side is totally fine.
I can even see a gap between the lower steel tube and the XZ plate. However, the brace is screwed to the plate without a gap if you look from the other side. If I measure the angle of the YZ plate (digitally) during movement of the Z axis, I can see that it tilts about 0.3°, the other YZ plate stays perfectly still (within 0.05°).
I will try to attach a photo from my phone in a reply. Honestly, I just have no idea where to look or what the reason could even be.The only thing I can think of the “z stub distance”, as the documentation is still missing this part But honestly, I think there is more to that.
I can see it. looks like more than 0.3 ° though. Are your gantry tube lengths the same and just shorter than the desired spacing by a mm or 2? It would appear that your strut plate holes are skewed a bit or the brace attached to the xz min plate is on the screw head of one of the linear rail connection bolts. There should be notches for those, but on the xmax side typically.
Thanks! The 0.3° I was referring to is the change in tilt as the Z moves up and down, in absolute numbers it is certainly more for sure.
I measured the tubes and they seem to be on point. For the top tube, it also fits perfectly. The XZ plates are straight on the YZ plates. It somehow is the brace which is not flat on the XZ plate, but looking from the top, it all looks flush and the screws are thight. it is just when looking from the front that there seems to be a gap between XZ plate and the lower part of the brace and tube.
I am wondering whether I should just try reprinting the brace and hoping this fixes it. But it is going to be a pain to replace
I have replaced that brace but it changed absolutely nothing. I have verified that the beam is square in itself on all 4 sides. I really dont get why attaching this square beam to the XZ plate makes everything so wonky. I have double checked all the screws, everything seems to be flat and good.
Can you take a very close picture of where the rail meets the aluminium plate, please? And if you loosen the plate, are there any markings of the tube in the aluminium at all? Even slight ones?
will try to make a picture when I am home again. Yes, at least on the Xmax side there are markings in the aluminum.
I wonder whether I should try to cut struts which are like 2mm longer, so the tubes dont touch anywhere. But its going to be difficult as the machine is not really useable at this point. Would need to build ir back to temp strut plates.
Looking at your pictures your tubes/rails are both too long. They absolutely need to be shorter than the beam by at least a millimeter. You have a spare 30mm so 1-3 short is ideal. I should have this in the instructions and calc, I will double-check.
Hello,
Just to verify as I am coming to this part of my LR4 build:
The strut plates should be like 2 mm longer than the tubes (1mm clearance for each side)?
because the calculator still gives exactly the same number for tube length and strut length.
It looks like the metric version may have been fixed, but the imperial version is now way off. Probably still a work in progress, the x-rail to strut plate difference is now showing 2". This was for my intended working width of 42".
I’m just glad this topic came up today. I’m probably going to be cutting the x-rail later today or tomorrow… It would have sucked to have gotten that wrong…
But honestly, I think there is more to that.
