Core One first prints early layers filiament bumps  

RE: Core One first prints early layers filiament bumps

That's "normal" for certain profiles and filaments. If the filament flows easier, than others and the first layer temperature is quite high, you get some "over extrusion".

Also, the Core One firmware is set to squeeze the filament nicely onto the bed, to get it to really stick.

Adjustments, if the first layer doesn't look good enough for you from the bottom of the finished part or it becomes too messy to not be hidden by the next layers:

- Lower the first layer speed. The default is pretty fast to get a really clean first layer. I drop both values for the first layer to 25 mm/s, if I want a better sticking and cleaner first layer.

- Lower first layer temperature. Most PLA filaments have a recommended range of 195-230°C. The Prusa profiles are set very hot. Nice for sticking, but not always great for nicely looking prints.

- reduce extrusion multiplier to something like 0.97. This will simply push less filament through the nozzle. However, that's for the whole object, so if the real top layers look perfect, don't adjust this.

- reduce first layer extrusion width. Wider first layer lines tend to stick better, but reducing it a little bit, probably won't hurt.

All these factors are increased due to the high-flow nozzle. At higher speeds (after the first layer), the filament will spend less time inside the nozzle and won't be as hot, as during the first layer, reducing the flow.
So I personally reduce the speed and temperature for the first layer.

You can also get really into detail and edit the M221 S100 line at the bottom of the Custom Start G-code to something like M221 S95.
But then you need to add this into the "Before layer change" G-code field:
{if layer_num == 1}M221 S100 ; Reset flow rate to 100% from second layer on{endif}

RE: Core One first prints early layers filiament bumps

Thank you for the detailed explanation.  I'm going to try some other PLA filaments to see how they do.  Currently printing with 95A TPU and that is going well.

RE:

You are absolutely right, here is my first 0.4mm speed PLA prusa print.

The printer is an upgrade from my MK4S,  i think is correct pfor the first time.

I'm still having problems calibrating the Y axis, it's not permanent, I have to redo it often

RE: Core One first prints early layers filiament bumps

I had a similar issue  where the first / second layers curls in a similar manner with pla . I got rid of it by turning of the chamber fan for the first 2-3 cm and than let it run at max 20 %

Posted by: @extrudingthoughts

The filament seems to be building up on the 0.4 mm nozzle and falling off.  Later in the print this does not seem to be a problem and the top surface of the print has no issues.  Filament is Prusament PLA included in the Core One kit sliced with the Prusament PLA profile in PrusaSlicer.   Printer firmware updated to 6.3.3.  On my MK3S+ I would adjust the Z offset but I don't know where to start with the Core One.  

 

 

 9e72ef00-core-one-early-layeres-problem.jpg

RE: Core One first prints early layers filiament bumps

@extrudingthoughts May I kindly ask (and a PM/email if ok if we don't want to pollute this thread) how you are doing that exactly? Any change in settings? How about feeding the TPU into the extruder, any special procedure?

Thanks in advance

Posted by: @extrudingthoughts

Thank you for the detailed explanation.  I'm going to try some other PLA filaments to see how they do.  Currently printing with 95A TPU and that is going well.

RE:

I had the same problem on my freshly upgraded Core One. The cause is, that the filament is squished to much and thus bulds up on the first layers. I managed to solve this by changing the Z-Offset setting on the printer profile to +0.025. Had to play around with that value to find the optimum. Now i have perfect first layers again.

Please, if you have the same issue, get in touch with prusa support and tell them, that we need a setting directly in the printer to change the z-distance, as we had it on our MK2/3/4s.

before

after

RE: Core One first prints early layers filiament bumps

not allowed to send private messages xD . Either in the menu temperature control , you can turn it or set max power for them. It is also possible to set it via g code >

M107 P3 - turn of 

M106 P3 S255   - set speed to 100%

i do it with a snippet : {if layer_z >= 20}M106 S51{endif}