Is a skirt really necessary?

[NF6X]

My understanding is that the purpose of the skirt is to get the extrusion flowing smoothly at the start of the print. Is it really necessary, given the initial drool over the side of the bed that Simplify3D performs to prime and wipe the nozzle?

[ryaneb85]

The first few mm of the skirt never goes down well on on my prints despite the purge, so if it didn't print the skirt first, it would be the first few mm of the final piece that didn't go down well. Everybody may be different, but I certainly need a skirt. However, you can probably keep the number of outlines to a minimum, i.e. 1

[SouthSideofdaSky]

Strictly speaking it probably isn't necessary, but as ryan said the first few mm of my skirt never go down well despite the purge. I use a 2-outline skirt on every print for this reason and also to verify the outlines are bonding together and the z height didn't somehow get tweaked, etc.

[NF6X]

Thanks! I was wondering because my skirts seemed to be coming out perfectly on my new M2, vs. the incomplete and blobby skirts produced by my previous printer+slicer combination. I don't have much experience with my M2 yet, but so far the purge + wipe cycle seems to be more effective than the purge pillar that my previous combination used.

[ednisley]

to get the extrusion flowing smoothly

... and to pressurize the plastic inside the hot end. The extruder drools at zero pressure with the filament not moving, so the hot end end has an air bubble inside. It takes 10 or 20 mm of filament to refill the hot end and stabilize the extruder pressure; better to do that on the skirt than whatever you're printing.

My heavily modified startup G-Code plants a booger on the front end of the platform before starting the skirt:
https://softsolder.com/2015/03/31/maker ... -whatever/



After wiping that mess off, the skirt usually looks perfect, but I'm willing to sacrifice a few more millimeters of filament to make absolutely sure Things Are Ducky in there...

[NF6X]

to get the extrusion flowing smoothly

... and to pressurize the plastic inside the hot end. The extruder drools at zero pressure with the filament not moving, so the hot end end has an air bubble inside.

Aha! I had not considered the effect of having no back pressure during the purge. Ok, so the purge helps a lot, but the skirt still has a role to perform. Thanks!