PrusaSLicer 2.3.0 Beta2 - Ironing causes Nozzle Jam!

PrusaSLicer 2.3.0 Beta2 - Ironing causes Nozzle Jam!  

Active Member

I've been playing with the latest beta for a day or two, really like it.  But today I had a large print that I wanted to use the new iron feature on.  
This print had about .5 of the print bed to iron.   I used the default settings by selecting Ironing and all top surfaces.  

I believe what is happening is that the PLA is at temperature for so long and really not extruding all that much during the process.  The result was burnt PLA clogging up my print head.  

Was printing Hatchbox Silver PLA at 210C on to a 60C bed.   Never have issues with these settings.   

This feature may need some tweaking or better documentation to avoid this issue.

Posted : 06/12/2020 11:20 pm
Active Member

In Github issue #5389 the downsides of ironing have been mentioned. I found a way to get around the issues for my current use case*.

I try to print a couple of parts with a surface that shall be ironed. One time the printer manages to print two perfect parts and fails at the third one, and the next time the nozzles gets already clogged while ironing the first part.

I can't change the size of the surface and I can't print it with the relevant surface being the first layer. So I tried to speed up the ironing process, to avoid the issues. The tip of the nozzle is 1mm wide. The default "Spacing between ironing passes" is 0.1mm. Let's increase this.

Changed spacing from left to right: 0.1-0.5, the sixth one was printed without ironing.

Printed simple objects with different spacing between ironing passes.

The quality of ironing with spacing of 0.2mm is sufficient for me. But even with the increased spacing I still faced issues.
Next parameter: Speed. The default value for Ironing is 15mm/s. I tried 20 and 25mm/s. Both worked fine.

My solution, this time:
Spacing between ironing passes: 0.2
Speed - Ironing: 25mm/s

*Use case:
Surface to be ironed per part: 4.5cm²
Printer: Prusa i3 MK3S
Nozzle: 210°C
Material: PLA (Das Filament, tannengrün)

Posted : 09/12/2020 4:52 pm
IBGeek liked
Active Member

Update: Still doesn't work reliably.

Meanwhile I have modified the gcode to do the ironing in two steps and print the layer of another object in between. This reduced the surface to be ironed in one run to about 2.25cm², but it still doesn't work every time.

Posted : 11/12/2020 4:18 pm
IBGeek liked
Estimable Member

I've been getting constant jams with PETG, I've tried changing the spacing to 0.2, I suspect it's to do with the quality of this PETG though as it's not very consistent.

I've been using it on my MK2.5 and have only had a few successes, I'll give it a crack on my MK3 and see how it goes with good PETG.

Posted : 05/01/2021 4:00 am
Active Member


I am having the same issues as you are describing. I am mainly printing in ESUN PETG at 230 degrees with cooling fan on at 40%. 

Apart from the speed and layer height, have you changed the extrusion amount from 15%?

I might set up some tests similar to yours and see what setting will give me 100% success

Posted : 13/01/2021 9:54 am
Active Member


I did not touch the flow rate for ironing. I think the amount of additional material will be too low for making a relevant difference.

Instead of passing the already printed surface a second time with a low flow rate and only a little spacing between passes, we could try to print with a reduced extrusion width for "Top solid infill" (and slightly over extrude).
The first parameter can be set in PrusaSlicer (Print Settings=>Advanced=>Extrusion Width-Top solid infill).
Overextrusion only for the last layer requires manual gcode modification (slice with default setting and save, slice with overextrusion and replace relevant section in first slicing result).

Didn't try it. It's just an idea.

Posted : 17/01/2021 10:14 am

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