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So i am working on finalizing my working set for PETG esun filament.
I can not seem to get even the tiny few fine hairs gone... otherwise its great.
please see pics for settings and results.
would love any help to finally get rid of those last hairs :)
thanks
http://s1132.photobucket.com/user/du...0print%20tests
okay you've got print speed at 40mm/s and movement speed at 150mm/s.
At what point does it get a chance to retract the petg before the carriage zooms off somewhere else.
Try dropping your carriage movement down to the same as your print speed.
gives everything a chance to work before the print head crosses gaps.
your firat layer height is 0.36 mm - why ?
And you're only extruding at 87%
Got to say those are some really weird settings. They seem to cancel each other out - so why change them in the first place.
Can't see any temperature settings.
aardvark... thank you for the info...
First off. 245c.
movement speed I didnt realize previously , would have an effect on things. As fast as the hobbed bolt turns i thought it sucked up that filament faster, perhaps im wrong.
First layer - I was under the impression that you want to keep your layer heights a multiple of your nozzle size. mine is .4, so i chose a .24 layer height as a multiple. Thus making .36 (150%) the first layer. I actually realized that I took this down to 100% in my latest prints (but s3d crashed, so the settings didnt change). first layer height will be 100% and its a PERFECT first layer with where I have my Auto Bed Leveling set.
So ive tried extrusion multipliers from .87 to .94 with petg. I find my best measurements for this particular filaments are in the .87 range.. petg has a huge range of multipliers across manufacturers etc. I have some spools that are correct at .98
0.24 is not a multiple of 0.4
hahah, right you are.. i was thinking .04.. touche :)
It doesn't matter anyway if the layer height is a multiple of your nozzle size it is just not a good idea to exceed 80% of your nozzle size for the layer height.
The reason is that it doesn't get squished enough to make a strong bond to the previous layer if it cannot get enough plastic into the gap.
gotcha.. i never go above .3mm, mostly all .2mm anyway, so good info to know.
I modified some speed settings and am running a test retraction now.
let you guys know how it goes.. im sure youre losing sleep haha
so i went with extrusion width .4 (not automatic).
multiplier .93
layer height .2
first layer 100%
XY movement of 40mm/s to match printing speed.
Results are better .
Its probably considered pretty damm good for pETG, but if i am going to be printing some larger objects on a 16x16 bed i want to really get it dialed in.
http://i1132.photobucket.com/albums/...psgz3u2yye.jpg
ok.. ran a couple more tests. one with a higher value of 2.0 for the retraction distance.. it made it worse.
then from the stock 1.2 that i was using down to .7 and it made it better again... strange that a lower value would improve the quality.
it seems 1.2 and .7 have about the same amount of stringing (pic above). not sure if i should try a coast or what.. cant seem to get rid of those last few hairs.
coasting makes it worse... damm..
have you actually measured the actual width of the extruded petg ?
Seems to me you're pretty much just changing things at random without any actual logic.
The extrusion width setting should be set to the actual extrusion width. So when you load filament and it extrudes. That's what you need to measure and that's the number you put for the extrusion width. Otherwise the slicer is just working off incorrect settings.
okay just started using the esun petg I bought a week or two back.
And what makes the difference as far as stringing goes isn't how far you retract it - but how FAST you retract it.
I'm currently using 40mm/s - but basically keep increase that till the printer cries uncle !
(never did understand that phrase)
Currently printing at 235 and 40mm/s print speed.
Getting nice prints.
Thanks aardvark. I too get great quality prints, but if I had 10 things on the huge platform, it may not look great due to movement between parts, although it got MUCh better with m y testing. I built the EZBOT arm w/ 4 servos etc and 15 parts on the platform and it worked pretty well.
Ill run a test with a huge retraction speed.
strangely enough that had an adverse effect... I ran at 40mm/s print speed, 40mm/s travel speed, and 50mm/s retraction speed and it was one of the worst tests I had run... lots of stringing and globs at the top of each spire. going to run another control test at 25mm/s with the same settings/
weird - perhaps it's down to different brands of petg.
Tried colorfab and esun so far - esun definitely less stringy.
It also sticks better to the printbite and didn't show any sign of warp (shrinkage) whichthe coorfabb does a wee bit.
Got some real cheap stuff coming today or tomorrow: technologyoutlet petg.
£20 a kg !
See how that compares.
My two cents worth:
While printing, there is a temperature differential between the heating element and the nozzle as energy must be transported to the nozzle to melt the plastic. This is analogous to electricity, a current can only flow if there is a voltage differential (the driving force). Heat energy can only flow if there is a temperature differential (the driving force). The faster you print, the larger the temperature differential will be.
When you retract, you relieve most of the pressure from the nozzle. However, when extrusion stops there is no more loss of energy through the extruded plastic. Thus the temperature differential will resolve itself and the temperature in the nozzle will rise a bit. Because the plastic also rises in temperature, it will expand. As the nozzle opening is the only place it can go, it will continue to ooze until the temperature in the nozzle is constant.
There will always be a little bit of ooze (unless you can actually retract the plastic and create an air bubble in the tip of the nozzle, but with viscous PETG it is very difficult to do this), so some stringing will remain.
From this point of view, you want to travel as fast as possible from one point to another, not slowly. When going slow, you allow more time to generate this temperature-induced final oozing, thus more whiskers/strings.
In the end a good profile is a balancing act of multiple variables, there is no clear cut solution to one problem, without creating a new one somewhere else.
worth a try.
I just find that with any plastic, going from a slow print to a fast travel, tends to pull the plastic up into little spikes that can catch on the printhead.