I own a Velleman K8200.
Sometimes during a print the item that I am printing moves a couple of centimeters.
This ruins the 3D-Model.
If any one knows how to solve this problem, pleas let me know.
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Do you have a heated bed? what kind of plastic are you printing and are you using hair spray, glue, 3d lac or some sort of tape to prevent your prints from coming loose?
Regular multi-purpose glue(white, water soluble) is the most effective, cheapest way.
It will work with most materials(ABS,PLA, and even Nylon). No need to buy galorite for the nylon. A heated bed helps even more to prevent warping if you are printing large parts.
Not sure if you’ve resolved this or not. Unless the entire piece is detached from the print bed, it’s more likely that you are getting “skipped steps”. This is where the signals are sent to the stepper motors to move a certain amount, but they move a bit more, or less instead. It can happen for many reasons: Something in the way, additional resistance in the mechanism, damaged belts, etc.
On the K8200, skipped steps are often due to the output voltage on the stepper drivers. It’s a little tricky to adjust, but they can be adjusted up a bit to help resolve the issue. Follow the instructions in the assembly manual where they have you set this initially.
Since the K8200 has a fully moving print bed, large prints can get a lot of momentum going which can be challenging for the stepper motors to stop. I run mine with an “Acceleration” value of 400mm/s^2. This is done in the slicer app and limits how rapidly it goes from stop to full speed and back and helps with momentum issues causing skipped steps.
I recently had a skipped step on a print after not having one for a long time. I lubricated the guide shafts of the X and Y axis with a few drops of oil and haven’t had a problem since.
For shifts in the print, I would check to see if the motor pulley is tight on the motor shaft, and that the bed carriage can move freely in both x and y directions.
I noticed my print kept shifting only in the x direction. When i looked, the motor shaft was turning, but the pulley wasn’t. The solution I found worked best, was to flatten a side of the motor shaft with a dremel tool. This allows the grub screw in the pulley to sit flat against the shaft, and to be tightened worry-free.
Another possible problem area I would check is to make sure that the motors have the proper setting in the controller firmware.
