Hi,
Can anyone suggest why I got this heavy ribbed corrugated effect on my first print ( the board cover )?
Theses corrugations or steps are not individual thick layers they are built like that out of thin layers.
Have I set something up wrong?
Any ideas?
Thanks,
Stan
flickr.com/x/t/0090009/phot … 340835125/
flickr.com/photos/23414617@N06/14319783186/
flickr.com/photos/23414617@N06/14339883131/
Hello Stan,
It seems You have big Z axis wobble. Probably, the coupler or the spindle are not straight. You should get flexible coupler, print a new Z motor mount and upgrade to trapezoid spindle.
Hope this helps
Send the Z axis motor coupler back to Velleman for a replacement.
Thanks guys! I’ll look into those options for reducing z axis wobble.
Hi,
Looking at the print again though it seems that it ribbed out at same place all the way round.
Each layer gets bigger and bigger then gradually smaller and small again etc.
So it doesn’t gel with lateral displacement caused by wobble.
In that case each layer would be the right size but offset in the direction of the wobble.
Also I don’t see how the extruder can move laterally - it’s constrained to vertical by bearings and guide rods isn’t it ?
Stan
With Z axis wobble the layer height varies, so some layers get squashed more than others giving the all round ribbed effect. Velleman have had a lot of problems with the coupler (and Y axis belt drive gear) and will change these for you.
thanks steve_b,
do you know whether they will just replace it with the same part
or has some improvement subsequently been made to the design of the coupler?
stan
Hi Stan. No, they haven’t changed the design. The problems are due to bad machining of the parts, but supposedly they’ve fixed this.
If you know someone with a lathe though it’s a pretty simple job to make a replacement yourself.
Steve
With a rigid coupling you can’t get rid of the Z wobble. You must buy a flex coupler (costs about 3€ w/ free shipping).
Hi,
As a test you could try slowing the speed of the printer down.
I disagree. I don’t have any mods (100% orginal Velleman) and get this with the solid coupler:
The bands you see from 8mm up are where there is a significant change to the other side of the model and so the layers have cooled differently.
Hi steve_b,
If your original parts are perfect you can indeed get good results but if you have a Z-wobble it means your threaded rod is probably bent and it’s almost impossible to get it straight. The flex coupling greatly minimizes the impact of a bent rod and allows for a slight misalignment of the motor-coupler-rod assembly.
steve_b, you were very lucky to get a part that performed that well from the outset!
The (K8200) printer I’ve been using was plagued with poor quality prints and the cover I printed (and everything since) looked like Stan’s (linked to) images. In fact it looked identical.
I also thought that the layers expanding and contracting in unison, not wobbling left and right, could not be due to a wobbly z-axis, but many others have said it is, and this is now confirmed since I fitted the new Z-Axis Modification Kit (K8204), with a “precision screw threaded rod” and follower nut, with a flexible coupler to join it to the motor (from here: theelectronicsshop.co.uk/con … k8204.html).
It’s now much better, and nothing else I’d tried beforehand (taking off the top holder/bearing for the Z-axis threaded rod, etc.) had solved the problem.
I also changed to an E3D (V6) hot end with 0.4 mm nozzle at the same time and this seems to have has improved a lot of other things - I had lots of trouble with the PTFE cylinder above the hot end expanding and the filament getting stuck in there, plus lots of goopy stringing issues.
The first print I did with the new hot end (once I’d sorted out adhesion issues to the glass plate, which turned up again – I got fed up and decided to just use blue tape!) looked far better and virtually free from all of these issues.