symptoms of moist ABS?

[Peter Harrington]

 Hi there, I just switched color of plastic and am having trouble printing.  Let me expand on this "trouble":

-I have printed with this plastic before and had no problems, it was great.  I switched colors and let this plastic sit in an open plastic bag near a door that is open to the outside for around ~1 month.  

-I am using an MK6+ extruder and the plastic is from MakerBot Ind, it is 1.75mm ABS.  

-I can print now but after about 20min the ABS will stop coming out, even though the temperature is correct.  If I clean out the ABS, and start printing I can print for another 20min.  This is fine, but I would like to print some bigger pieces. 

Do these symptoms sound like the symptoms of ABS that has absorbed water?  I have seen other experienced Makerbot operators store their plastic in a sealed box.  

Thanks for the help

Peter

[Whosawhatsis]

Do you have anything cleaning the dust off of your filament as it feeds? Dust in your nozzle is nasty.

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[Stan Seibert]

The usual sign of water in the filament is tiny bubbles appearing in
the plastic as it exits the nozzle. Water trapped in the plastic is
superheated inside the nozzle, then bursts out of the surface of the
extruding plastic when it is exposed to the air. I don't think that
ABS which has absorbed water is more likely to jam an extruder.

I also agree with the dust hypothesis here. Do you see any residue
when you take a white cloth or paper towel and wipe the surface of
several feet of the problem filament?

On Jan 15, 1:34 pm, Peter Harrington <peter.b.harring...@gmail.com>
wrote:

[sto...@gmail.com]

Wet-
Another symptom of wet ABS is small sizzling, popping noises. the plastic gets bubbly textured. If you suspect wet plastic you can dry by using your home oven. Turn your home oven to the lowest setting. Mine is 170 degrees F. You do not want much hotter. Set the loose coil of plastic on cardboard or paper, not iron rack or metal trays. Place a layer of paper over to protect from direct element radiance. Leave for about an hour. Turn off oven and let slow cool. A plus is this kind of anneals the plastic releaving manufactured in stresses from the extrusion process. I've a theory to test- That annealed plastic will warp and curl less. Yet, to be tested.

Dust -
I keep my bot and plastic in a clean environment so dust is not a real problem for me. And the plastic is mostly covered. If dirt/dust is a problem there will be more odor as you print, some burning which, is distinct smelling and likely brown/black bits showing in the plastic parts. If you have dirt problems search Thingiverse for a dust cleaner. In the mean time a cotton swatch - girls and makeup stashes are good for getting these or a napkin. Tape to filament entry into stepper. You can moisten with rubbing alcohol, mineral oil, glycerin, veggie oil to clean the filament as it enters the printer.

Filament diameter variance within rolls.
I do have a roll that as I've gotten into it has begun to be inconsistent in diameter. This inconsistency does cause print problems. Re-check your filament diameter. Adjust your bot as required to tighten or loosen pressure on feeding filament.

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