cope413 wrote:I posted this on a fail thread i started that probably won't get viewed much, so I'll repost it here where it's most relevant...
I got my hands on a nifty piece of equipment last week when I got my dryer up and running.
Been running some tests on filament moisture levels and here's what I've found...
I tested 4 different filament samples.
All filament was thoroughly dried by baking in an oven for 18 hours at 185F.
Control sample was left out in the open air for 72 hours
Sample 1 - airtight bucket with desiccant, no heat - 72 hours
Sample 2 - airtight bucket with desiccant, 40w incandescent bulb - 72 hours
Sample 3 - airtight bucket with desiccant, heated and compressed air flow through the bucket at 3psi, 40w incandescent bulb. PID controlled compressed air heater set to 130F - once up to temp, air would kick on every 30-40minutes or so and would take about 6-8 minutes to turn back off.
My shop's average relative humidity over the past week was 44.6%.
I measured the Rh% of each bucket, and then immediately printed a cal-cube with it.
When left out for, the trimmer line still prints, but it gives prints a very different finish. It's actually kind of cool, but it's noticeably different. I didn't noticed any major issues with layer adhesion, but I definitely got "pops" which left some uneven spots. There was also a fair amount of blobs on corners, and on small radii I noticed a lot of stringing. Nothing that ruined the usability of a print, but definitely not ideal.
It printed cleaner than the stuff left out in the open, but not a whole lot. There was less blobbing on retracts, but still stringing and "pops" while printing.
Printed very clean for the first 30-40 layers. Beautiful. No popping, no blobs - just perfect. Started to get messier as it went. I surmise that the outside of the spool dried thoroughly and the filament on the inside winding didn't/
Perfect print. When I print with this stuff, I never want to print with any other filament again. Great appearance, prints like butter, and amazing strength. Great bridging ability, and excellent surface finish.
Nylon absorbs a LOT of water if you let it. There's likely a sweet spot between my Dryer Bucket of Justice and Awesomeness and the simple bulb-in-a-bucket. While I'm thrilled with my results, it's not really practical. I suspect that keeping Rh around 15% with some heat will produce the same results if the filament is allowed to dry for longer periods of time. Ideally, the filament would feed from the bucket to the extruder without being exposed to the air.
I'll post some pics of the prints when I get my SLR and booth set up. Tough to show the differences in surface texture with my phone.
Just wanted to post an update regarding the low-humidity molecular sieve dessicant. I ended up using just over a pound in my 30 gallon bin. It gets RH down to ~9% at room temperature, and with a 25w bulb in the box i'm down to 7%.
And I couldn't agree more about the trimmer line when it's nice and dry - beautiful stuff. I think I'll try dyeing the blue line black next...