Craftbot XL Print Issue - Maybe Belt Tension?

I have started having this weird issue with my prints that involve circles and/or arcs. This issue do not happen on straight surfaces.

It makes these ridges on the surface when it used to have a perfectly smooth surface. I have oiled the threads and other pieces, but it still does it.

Could this be an issue with the belt tension? If so, how do you adjust the tension in the belts and how do I know what the proper tension is?

See photo.Craftbot XL Print Issue - Maybe Belt Tension?

June 10, 2019

Crookknight Crookknight
Beginner
4 posts

6 replies


When I looked into belt tension last time, I've found 13N per belt here: https://www.thingiverse.com/thing:2023765.

These look more like acceleration artifacts. The plastic comes out at a steady rate but the head starts and stops at the end of the segments, so there is more plastic at the end of segments.

Try the same print at lower speeds, and use even more segments for approximating circles.

June 10, 2019

psanyi psanyi
Exalted
949 posts

psanyi wrote:When I looked into belt tension last time, I've found 13N per belt here: https://www.thingiverse.com/thing:2023765.

These look more like acceleration artifacts. The plastic comes out at a steady rate but the head starts and stops at the end of the segments, so there is more plastic at the end of segments.

Try the same print at lower speeds, and use even more segments for approximating circles.

I am using Simplify3D. Where do you find the settings for using more segments for approximating circles?

June 12, 2019

Crookknight Crookknight
Beginner
4 posts

I am using Simplify3D. Where do you find the settings for using more segments for approximating circles?

June 12, 2019

Crookknight Crookknight
Beginner
4 posts

You have to set it when generating the STL, I do not think that you can set it in the slicer, as there are no circles in the STL. I just assumed, that it is your design. If not, then you have to experiment with slow printing, slow meaning 20 mm/s.

June 13, 2019

psanyi psanyi
Exalted
949 posts

Would this problem just all of a suddenly occur? It was printing fine for the first 9 months and then this issue starting happening, which is why I thought it would be the machine and not the program.

June 15, 2019

Crookknight Crookknight
Beginner
4 posts

Did you print the same kind of objects and segmentation?
As for me it's just that the segmentation is somehow at the threshold the acceleration kicks in.
Best first to print another object / earlier object you know it's printed ok in the past, and see if this effect is occurring as well with it.
Otherwise it would be a first step to change the segmentation in your CAD software as Psaniy suggested as that would be the first thing comes to mind with me as well.
The acceleration settings can be changed by adding a line in your startGcode., as :

M1203 A2500 D2500 F1200; steeper acceleration.

default is M1203 A2000 D2000 F240. That means that at speed 240mm/min = 4mm/s the acceleration kicks in. That's pretty low. So some steeper acceleration in
M1203 A2500 D2500 F1200
Kicks in at 1200mm/min = 30mm/s
And with a little higher acceleration and de-acceleration.


June 21, 2019

Bartaar Bartaar
Service partner
1663 posts
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