good evening,
i´m having a problem mounting the Z carriage, when i slide it down the rods that are fixed in the plastic rod clamps it gets way too tight as it gets closer to the clamps and i cant move it all the way down. I have unmounted and remounted. I take it that it might be something that is out of its normal measure.
Can someone help me out here please.
Try to loosen a bit the bolts holding the linear bearings and see if it moves more freely.
I´ve done that, tried everything possible… is there a data sheet anywhere on the site so i can see if anything is out of measure?
Thanks
Hi hazzncrazy,
had the same issue on my printer. The missalignment was only 0.1 mm in my case (i.e. the smooth Z rods were 0.1 mm closer in the middle, near the Z carriage, than at both top and bottom ends) and the rods didn’t have any residual bending after releasing the stress. In the end, what helped, was using a 4.5 mm (or perhaps it even was 5 mm) drill to enlarge all the 16 holes in the two aluminium plates. After that, I was able to remount the Z carriage and adjust it to run smoothly.
Cheers,
kuraasu
Can you please confirm if ur measurement from the outside of the rods right next to the plastic parts is the same as mine? i think mine is way off and should be 80mm instead of the 81.2 that i marked on the image.
I´m thinking since the profile is also extruded the walls can be off measure.
Thanks
Iirc I measured 61.1 mm on the inside of the rods; that would then be 81.1 mm outside since the rods are quite precise.
that would mean mine is off 0,1mm like urs was and the widening of the screw holes would help…
i guess im gonna have to try that … even though the way it is wont even let me push the carriage all the way down… it seems tighter
Thanks
I have about 80.5 mm, top to bottom.
0.1 mm is not significant.
Hi raby,
I disagree, 0.1 mm can be very significant. The holes in the alu plates were (again, iirc, this was already 2-3 months ago when I had that “operation” on my printer) already near 4.5 mm in diameter, or in other words, the 4.5 mm drill didn’t remove much material. With M4 bolts inside those holes, that gives approx. 0.25 mm tolerance to either side. However, if the smooth rods are positioned further apart, the bolts are firmly pressed against the outer side of the holes, and the tolerance is gone. In this case, a dislocation (!) of the rods by 0.1 mm is very relevant. The bearings are under high radial load in this case, and they don’t operate well in this condition.
I don’t know if it’s the Z rod clamps that have these high tolerances in length, or something else, but your measure and hazzncrazy’s suggest that there’s at least 0.7 mm of possible difference in how far apart these rods are mounted.
Cheers,
kuraasu
how is it possible that i have 81,2 then, what is out of measure? is it the plastic clamps? Can someone from Velleman make a suggestion if i should consider going to my supplier?
Mine measures 81.1mm at the bottom and it works fine.
Please note that it does not need to slide all the way down, at the lowest position it remains about 30mm above the plastic supports.
I have the same issue.
For me, the measurement in the photograph to the outside of the rods is 81.1mm and, the diameter of the rods being each 10.0mm, the centres are therefore spaced at 71.1mm.
Given that the plastic bearing mounts are symmetrical, if you number the four bearing mount holes along any edge of the aluminium plates 1,2,3,4 and measure from say the left edge of hole 1 to the left edge of hole 3, this gives the spacing for the centres of the bearings (albeit without taking up any play in the gaps around the bolts for adjustment). This measurement for me is 69.1mm i.e. 2.0mm off the rod centres.
I have also measured the diameter of the bolts at 3.8mm, the diameter of the bearing mount holes in the aluminium plates at 4.4mm and the slots in the plastic bearing mounts at 4.4mm, giving a gap of 0.3mm available either side of the bolt in the mounting hole and a further 0.3mm either side of the slot in the bearing mount. By pushing both bearing mount outwards to the extreme the most I can extend the distance between bearing centres is therefore 0.3mm + 0.3mm i.e. 0.6mm per bearing and 1.2mm in total which still leaves the bearing centres 0.8mm short of the rod centres.
POSSIBLE REMEDIES
According to the calculation above I would need to drill out the holes in the aluminium plates to at least 5.2mm to widen the centres of the bearings to match the rods.
Alternatively, I am considering removing the corners of the plastic rod mounts such that they sit on the inner step of the extruded aluminium frame to reduce the spacing of the rod centres. I have measured the distance between opposite outer steps of the extrusion at 25.0mm and the inner steps at 23.0mm so this would reduce the rod centres by 2.0mm bringing them exactly into line with the bearing centres.
Could Velleman Support please advise the correct spacing of the holes on the aluminium plates and comment as this does appear to me to be an error and an issue raised several posters?
