Today I’ve got the K8200 package and started assembling it.
Most steps (till now, I’m not done yet) went smooth, but there is one thing that is worrying me.
The bed support plate does not move smoothly on the Y axis. Whatever I tried, loosening the screws holding the four linear ball bearings (bearing clamp y), tightening very carefully, the movement on the Y axis is rather rough.
When I remove the bed support plate, so that the four linear ball bearings can be moved separately, they move smoothly as intended. But once I attach the bearings to the bed support plate, movement gets back to rough.
SInce the holes in the bed support plate aren’t simple circular holes, but slotted holes, there is no definite way to attach the bearing clamps, and having the toothed washers on top of the slotted holes doesn’t improve handling.
In comparison, the X axis bearings are running smooth, and the Z axis mechanism also. So I’m at least partially abled to follow assembly instructions …
Any hints or clues what might be the problem with my setup?
i had some issues with the Y axis, as soon the black plastic holders where tighten too strong the platform was very hard to move at all.
you have to flush 4 linear bearings at the same time!
tighten the screws over cross, so the pressure is everywhere the same.
i did not tighten them very much, works better if you have more helping hands, and all can fix the holders at the same time.
also try to get the rod in perfect flush, a little bit tricky but its possible.
I would refine “Wrong Way”'s question a little bit:
Is at the moment already the belt and the motor attached?
If so, have a look if there are some wires of the motor are short-circuited (hot-wired), stumpled over this problem as an axis suddenly wouldn’t move as smooth as before and at the next moment (moving the whole thing a little bit) it moves as smooth as before …
@ Vellemans:
think, that is a circumstance that should be mentioned somewhere in the manual.
No, this is without the belt attached. When sliding the bed support plate, the friction is sufficient to move the steel rods in their fixtures - they can move longitudinally (lengthwise) for some 4mm.
Seems to be the tricky part, maybe thev’s hint will improve it somehow.
I’ve reduced friction somewhat by inserting some small shims (about 0.2 mm thick) between one of the bearing clamps and the bed support plate. Maybe the latter is slightly bent (I haven’t got proper tools to check that like a straightedge or a planometer, just tinkering at home).
Well, I’ll have to see how the reduced (but not absent) friction will be handled by the stepper motor. The rods are not polished, and the linear bearings are ball bearings, so that’s another level of smoothness than achievable with polished rods and a decent bushing, as to be found in better flatbed scanners or printers.
What makes adjustment difficult are the toothed washers, once they’ve “bitten” in the rather soft metal of the bed support plate, it’s quite difficult to move the bearing clamps around. Maybe a less “aggressive” kind of toothed washer would ease the process.
Did you finish building your printer? How does Y-axis move? Was it a problem?
I got my K8200 kit this week and started building it today. I’m at step 002 and my Y-axis also doesn’t move easily and I’m wondering if this is going to be a problem later on…
Yes, I finally finished the build; it took me some time since my kit suffered from the well-known “bag 30 incompleteness syndrome”. Velleman kept their promise and promptly delivered replacement parts.
The movement, when done by hand still seems rather rough, but is sufficiently smooth for the stepper motors to operate. I’ve had no wiring problems and apparently the mechanics are fine also.
The print bed is another story; the heated PCB isn’t flat right out of the box and when mounted to it’s support, it bulges in the middle. In addition, the countersunk holes in it where much too small, when inserting the bolts, their heads weren’t flush with the bed’s surface, but stood out for more than 0.5mm.
A remedy was using a countersink drill and enlarging the countersunk holes in the PCB.
I’ve tried the famous IKEA mirror (grey backside up) and got my first two test objects printed with it. Fixing the mirror to the printing bed is rather suboptimal, so I’m now experimenting with an aluminium plate (21.5 cm x 21.5 cm x 2 mm) with four countersunk holes in it’s corners on top of the pcb. Flatness seems to be quite good, but stickiness … well, it does not stick enough. Now I’ve got to find out what the famous “blue masking tape” is and what to use instead of it – since I live in Germany, ordering things like that from the US would be kinda expensive.
you can use half pattex strips (20x40mm) = 20x20mm in each corner to attach the mirror.
they can be used till 90°C. you have to raise temperature to 55°C because of the gap between the heated bed and mirror.
to print on alu you have to use kapton (botom is like a mirror on printed items) or blue masking tape, its called “Maler Klebeband” but this gives a rough finish on botom.
both should be available in germany.
Thanks for your reply and all the info. Going to check bag 30 now…
I guess building this printer isn’t as simple and straightforward as I imagined it would be. But that’s fine… I like building and I like challenges.
So well, I think my Y-axis should be fine, too.
I’m still far from mounting the heated bed but I guess mine will also not be flat - seems to be a common problem.
Thanks for the reply. Unfortunately, DIY stores in Germany are a class of their own, selling brands not known in other parts of the world, thus stuff sold in the UK is different from stuff sold in Germany. That’s one of the few things were shops are not similar and replaceable, with nearly everything else you see the same stuff, be it in Italy, Britain, France or Germany – all the same, no difference. Just slightly different prices and slightly different muzak …
Anyway, I’ll just try what I presume could be a german simulacra of “masking tape”.
