[Solved] First layer problems suddenly occurring

ragde

Hello everyone,

My new coreXY is now running and was running quite great for several prints but suddenly it started having problems with the first layer, especially, when the layer is a quite large flat plane.

I am currently running the latest beta of reprap and except for a previous problem with cold extrusion it works fine. Even input shaping helped reducing the y-axis ringing.

The problem with the first layer happens with and without input shaping. Haven't had this issue before and it looks like the printer head isn't moving correctly when laying down the next line.

Checked the belt tension, and stepper motor currents etc.
Oh, and it isn't a problem with bed adhesion, small prints stick without problem and the printer moves correctly.

20230314_144447_HDR_(1)_(1).jpg

infiniteloop

@ragde said in First layer problems suddenly occurring:

Oh, and it isn't a problem with bed adhesion

The image tells a different story. How fast do you print your first layer, what speed reaches the head on wider distances?

ragde

@infiniteloop I know, it looks like bed adhesion but I printed at 60-80mm/s before on first layers and had no problems. As I said, small surface areas are no problem.
For testing purposes I even went down to 10mm/s on the bigger prints and the printer head just doesn't move enough and keeps hitting previous lines.

Here is another picture where it even grinds holes into the previous lines.

20230314_182023_(1).jpg

infiniteloop

@ragde

I even went down to 10mm/s on the bigger prints

If you get a decent first layer for small but not large objects, one difference is that, on smaller parts, the head doesn’t always reach the intended speed, due to acceleration limits. Admittedly, 10 mm/s are extremely slow-mo, so let’s look at some more options:

Turn your part cooling fan off for the first layer, then…
… try higher and lower extruder temperatures
Play with micro-stepping, maybe your PLA wants to be squished into the surface?
Layer height: with a .4 mm nozzle, try .2 and .3 mm - whatever works to achieve sticky long lines
Bed heater: experiment with 50-70°C
Turn off input shaping
Try a different filament brand

engikeneer

@ragde I'll also add to try cleaning your bed. You're hands will leave a small oily residue on it after a while which can make it harder for parts to adhere

ragde

Ok, little update.
First I played around with cooling and temperatures and cleaning the PEI sheet with alcohol.
Helped a bit and increased stickyness even more but the problem persisted.
Then I saw, that the printer also had problems with some round corners on my testing file. First I increased the current for some more torque but didn't do much. Then I hooked up two spare stepper motors and voila, the problem is gone.

Gonna test the stepper motors, to find the faulty one, but at the moment the printer is working fine again.

Thanks for your helpful input.

jens55

@ragde, it makes no sense that stepper motors would cause this unless of course we are talking Z stepper.Based on what I see, I would say that your z clearance between head and bed is wrong. This kind of result is quite common (well for me anyway when things are not adjusted right).
Yes, speed and bed temp as well as bed cleanliness all can cause similar results but as you say, you have that covered. What I tend to do to get my z clearance just right, I print a 2 layer square 100mm * 100mm and then play with babysteps during the very first layer.

ragde

@jens55 I'm actually kinda baffled, too. I am using a bltouch and did roughly 10 offset measurements. So I thought that I could rule out the head and bed clearance. But yeah, I switched out z-axis steppers and the bed compensation probably didn't work any more.

Now I am just glad that it's working again and I can finish the easter bunnies for my class to paint.