Jory
1
I’ve been noticing that my parts have been printing very short compared to the models and I’m getting some noticeable banding (both X/Y on problem layers). I printed out a quick 20mm test cube and noticed that there are some layers that look like they are squished. The squished layers start between 9-12mm up and are random from that point (other parts have squished layers that are much lower and more random). Top/bottom fill look great, walls up to the point of the squished layers look good too. Overall height is only 19.10mm, which is quite a ways off, while the X/Y were both around 19.98mm. I measured (approximately) the layer thickness under a microscope and each layer was only 0.12mm or so thick which is WAY off from the 0.20mm specified in my slicer (Simplify3D). Here are the print specs:
Print:
PLA
210°C - Extruder / 60°C - Bed (1st layer only, OFF for remaining layers)
40mm/sec
0.2mm layer
40% infill
So now I’m curious why the layer thicknesses are very thin compared to the slicer setting and why my overall height is so short. I thought I had mechanical issues but I found no binding. The issue shouldn’t be with the X or Y since the layers with the problems are uniformly squished looking (larger than the other layers in both the X/Y directions). Where should I start with troubleshooting?
1) I checked the firmware for my e-steps and 3/8 ACME nuts/rods…looked correct. Would the e-step errors be random like that?
2) No binding issues…maybe backlash?
3) Material shrinkage? What’s the best way to adjust for this without affecting X/Y?
C_D
2
Z motor missing steps perhaps? Overheating, binding or loose wiring maybe.
Hi Jory,
Models printing at in correct height can be caused by a few different factors.
first check that your Esteps are in fact correct, measure the distance from your bed to a point on the carriage, under manual commands move your z axis 100mm away from the bed, measure again… It should be your original measurement +100mm movement. If it matches up move on, otherwise you have some math to do.
next thing I would check is mechanical binding but you say you checked for that, (we had a printer that moved correctly under manual control but would bind during print simply because it was attempting to move the z axis too fast… Also caused this issue)
stepper current, if it’s too high the controller overheats and resets causing missed steps, to low and the motor doesn’t move far enough.
check this and get back to us
1 Like
bilsch
4
Check your z movement speed. What happens if you do a 20mm z lift do the motors sound bad or stutter? I’ve had issues like this and that z max speed was the culprit
Check that your z rods are not loose. Also check that you have no slant on your x rods. Does this happen with all prints.? Or just the one file? This issue could indicate a bad stepper motor as well. Material shrinkage is usually caused by too high a temperature. The layer does not cool before next layer squishes it down.
Jory
6
Got home, added a small fan blowing across the exposed Ramps/stepper drivers and ran 3 more test cubes. Result: no more squished layers! I guess having the printer set up in a small room with no air conditioner during a hot Texas summer is enough to make things hotter than normal. I’ll keep you posted if I have any more issues with this as I get back to printing larger parts again. Hopefully this is the fix!
1 Like
Jory
7
Ooops…added comment below.
Are you printing PLA without active cooling. This could be the problem.
Good deal. Happy printing
rowow
10
Increase your extrusion multiplier. Otherwise I will need photos to determine the issue.
Looks like you got some good results. I wanted to add that my machine started to have layer issues of larger prints and what I found was a bit of oil on the Z threaded rod did the trick. It seems it was slightly sticky and when it hit a certain spot the turning moment of the rod was enough to skew the build plat ever so slightly.
Thanks for letting us know what the fix was! I am excited to get my dual blower fans to see how that helps my pla 
