What's the use of a "skirt" in g-code

Snapmaker Luban
1

I don’t understand the need for the “skirt” created when generating g-code for a 3D print. The nozzle lays it down before the first layer of the job is printed. Invariably it doesn’t adhere to the print bed, and ends up getting involved in the first layer of adjacent objects in the print. Is there any way to suppress the thing during g-code generation?

2

I’d just leave it, we always use a skirt or something similar. It ensures the nozzle is primed and your first layer will be complete.

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3

If your skirt isn’t adhering properly that’s a sign you have problems with your calibration or temp settings. Or your bed isn’t clean or that you need to be using something to help it adhere.
Skirts are really useful for priming the nozzle and getting filament flowing.
I always use a 3 pass skirt (unless the print I’m doing needs a raft or brim) - makes it easier to remove it if it’s stuck too well. It gives me a chance to easily see what’s happening before it even starts the first layer.
If you don’t like it you can turn it off. I did at first but have come to really appreciate it.
-S

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4

Suppressing it is possible (in Luban, it’s under Adhesion in the custom print settings), and I usually print without . . . but you really need to figure out why it isn’t adhering before you do that.

5

Thanks for the reply.

Am printing with the spool of filament that was delivered with the Snapmaker 2.0. The nozzle is at 205º, and the print bed is 70º. I have cleaned the bed with isopropyl alcohol, and though the skirt isn’t adhering, all other objects in the print job are adhering too well and are difficult to get to release.

Print bed has been properly leveled and calibrated. My temptation is to raised the nozzle to avoid over adhesion of the actual print job objects, even though it will cause the skirt to adhere even less well.

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6

Depending on the shape of your object it sounds like you still might have a bed levelling issue. When you get a chance:

  • With the bed hot and the nozzle cold slowly jog down to Z=0
  • Then jog around in X and Y to approximately where the skirt and prints are
  • At interesting points measure the gap with the calibration card or feeler gauges

Is the nozzle actually moving around the bed the same distance away from the bed? It should.

With what I’ve experienced and many others here I would be floored if it’s correct. A common problem is as the bed heats up the metal undercarriage shrinks and expands in a way that curves the bed. Typically the recommendation is to trick the controller to perform calibration with a hot bed by letting the bed heat up for 15minutes or so and then performing a calibration.

There’s any number of other bed levelling issues - these beds are not very flat, and a 3x3 grid is insufficient. 5x5 is the minimum recommended, which also happens to be the maximum the touchscreen can do. But if you run the calibration gcode manually you could do a 7x7 or any other number.

7

Hey, Brent,

The print job has a number of objects which occupy most of the print sheet. Is it possible that the edge of the sheet is cooler than the rest, and thus causing the skirt to be unable to adhere properly? This seems unlikely to me since pieces directly adjacent to the non-adhering skirt, are actually over-adhered and difficult to remove once the print job is finished.

8

I agree with you, that seems unlikely.

Hold a straightedge across the bed. Is it visibly curved down at the edge? Mine is. Check out the measurements I got here: On achieving a perfect level - #192 by brent113