Stringing: Make it go away

[Eric Pavey]

I've recently starting printing topo maps, and noticed a loooot of stringing going on that I wasn't used to (compared to "less complex" prints).  Recently did the Make magazine torture test, and got a bunch of stringing on their "spikey" print thing as well.  I've also recently upgraded my Replicator 1 to Sailfish:  Overall, while I like the quality, I just see more 'stringing' on prints I wouldn't have in the past.  For example, if I print a box with an open top, there will be stringing stretching from corner to corner on the inside of it that I haven't experienced before.

Specs:  Rep1, Sailfish Firmware, Makerbot Desktop slicer, PLA @ 230, HBP off, 200 micron, 90/120.

I've been trying to read about this, but haven't found a silver bullet yet (maybe there isn't one?).  I've read up on the deprime settings, so the below two images show the results with it at the default 16, and 0.  About the same, 16 slightly better.  But both bad.

Is it time to start fiddling with retraction settings in a custom Makerbot profile?

Any thoughts or suggestions appreciated.

[Bonekollector]

Lower your print temperature to 210 for a first test - eliminated the majority of stringing for me

[Dan Newman]

On 11/12/2014, 8:33 PM, Eric Pavey wrote:
> I've recently starting printing topo maps, and noticed a loooot of
> stringing going on that I wasn't used to (compared to "less complex"
> prints). Recently did the Make magazine torture test, and got a bunch of
> stringing on their "spikey" print thing as well. I've also recently
> upgraded my Replicator 1 to Sailfish: Overall, while I like the quality, I
> just see more 'stringing' on prints I wouldn't have in the past. For
> example, if I print a box with an open top, there will be stringing
> stretching from corner to corner on the inside of it that I haven't
> experienced before.
>
> Specs: Rep1, Sailfish Firmware, Makerbot Desktop slicer, PLA @ 230,

PLA @ 230C? Try 200 - 205C. That will help a little. After that,
adjust the retraction settings in your slicer.

As to using firmware deprime for retraction-on-travel-moves, it really isn't meant
for that. And it only works for retraction-on-travel-moves if your slicer
does something really stupid: disables the extruder stepper motor(s) on travel
moves. Keep in mind, there's nothing in X3G which says, "Hey, I'm about to
do a travel move!" But, when MBI introduced RepG 37 or so with SF-50,
they made the gcode disable the extruder stepper motors on travel. Sailfish
can detect that -- the extruder stepper motor being disabled -- and do a
deprime retraction then.

So, the deprime is *only* helping if

1. You're using a slicer doing the very stupid thing of disabling
the extruder stepper motor on a travel move, and

2. If you have Sailfish 7.7 or later, you have enabled "deprime on travel"
moves. It's disabled by default.

I'm not sure if more recent versions of MakerWare are stupid enough
to disable the extruder on travel moves. They may be; same people
who thought it a good idea for RepG brought us MakerWare. (It's a
dumb idea in that it allows the pinch gear in the extruder to free-wheel
and thus allow pressure in the melt chamber and stored elastic
energy in the unmolten-but-compressed filament to push the filament
back out of the extruder by some unknown amount. A big problem for
3mm extruders and the Asian clone 1.75 mm extruders as well.)

What you should do is leave deprime at 16 in the firmware, ensure
that "deprime on travel" is NOT selected (RepG Machine > Onboard Preferences;
MakerWare via the Sailfish EEPROM maps), make sure that Extruder HOLD is
enabled (LCD under Utilities > General Settings; RepG Machine > Onboard
Preferences; MakerWare via the Sailfish EEPROM maps). Then adjust
your slicers retraction and push back settings.

Dan

[Joseph Chiu]

That angled branch is a sign that the PLA is too hot. If you look at the extruder as it travels, you'll likely see a drop off melted PLA forming at the tip. Try reducing by 5 to 10 degrees and try again.

[Eric Pavey]

Lowering my temp to 210 helped, see below.  I've printed at @230 for a couple years now:  I always hear about people running PLA at 190-210, but my rep1 won't extrude anything under 200 at all (well, last I tried), and 210 in the past seemed questionable.  Then makerware set 230 as the default for pla and I gave a "shrug" and went with it.  I'm sure this will spawn some comments ;-) 

I'll try printing @ 200 again and see what happens.  But in the past I just got a lot of clicking from the extruder.  I'll also look at the firmware settings you mentioned tomorrow dnewman.  Thanks for the help everyone, if I get better prints I'll post'em.

[TobyCWood]

Every spool can easily be different. As can the filament's performance for different objects. I verify my filament's lass point and optimal fusing temp on EVERY new spool.... or I waste the first print learning.

[Eric Pavey]

Funny how one can base an entire system on faulty data:  Per above suggestions, I tried printing at 200 and 190.  I'd never had success in the past printing below 200, but today, no problem.  Lower the temp, the better the results which you ca see below.  Still stringing, but much fewer "thick legs".  Haven't done any other tweaking yet.

Which raises the question : Does anyone have test models, like I use below, to "check out" a new roll of filament?