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Dehydrating filament

Discussion in 'Filament' started by Lance Weston, Mar 18, 2021.

  1. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I hear you on the filament cost and for anything I am unconcerned about (i.e. test print, print that is not itself visible or structurally important, things like that) ... I use the cheap stuff.

    I only use the Taulman or ColorFabb when it matters. When it does matter those are two sources I rely on.

    Generally speaking the R1 series can eat just about anything and make it look decent. My delta printers and the C2 are more picky.
     
  2. DavidR

    DavidR Member

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    Yes those almost certainly are cobalt II chloride. The hexahydrate is pink, dihydrate is purple, and the anhydrous form is blue. I just double checked and the hexahydrate decomposes in the range of 40-50C so while the machine is on I doubt they are reliable.
    That same compound is used as an indicator in dessicants. When they turn pink they are saturated and you know they need to be replaced. As long as there is dessicant in the sunlu moisture will continously be absorbed from the interior atmosphere. They can be recycled by simply putting them in an oven for an hour or two. I use these:

    INTERTECK PACKAGING 1 Gram Silica Gel Packets - Blue to Pink, Rechargeable Desiccant Packets and Dehumidifiers (Indicating, 200 Pack): Amazon.com: Industrial & Scientific
     
    #22 DavidR, Mar 24, 2021
    Last edited: Mar 24, 2021
  3. Lance Weston

    Lance Weston Active Member

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    I have again fooled myself by making assumptions; by looking at the rolls only at end of printing rather than before and after printing. The assumption was 1: all the filament was the same, 2: that the dehydrator at higher temp was making the filament brittle. I put three new rolls of GST3D filament on three machines. The RH% strips registered less the 10%RH on all. One roll the filament was so pliable I could not break it by had it had to be cut, the next roll the filament could be broken by bending it back and forth many times until it broke. The third roll was brittle enough to snap the filament in half. I set all dehydrators to 50C. All three rolls were identically pliable at the end of print to what they were at the beginning,of printing, and all produced prints of identical quality.

    Mark Tomlinson related that he can print well at 40%RH.

    After spending months making changes to my R2, the printers are finally reliable, giving me high quality production prints. I define reliable as: Printing out at least five consecutive rolls of filament with out a glitch and without losing print quality. I have made three changes to the R2 to effect reliability and quality improvements.

    1. I put in dehydrators that reduced the RH% to 10%. It looks like this was not the problem.

    2. I modified the print head to use an adjustable pressure dual gear extruder. I can not measure if this is an improvement but suspect is because it distorts the filament less has more grab and extrudes the same amount regardless of filament temperature.

    3. I do a filament load at the end of every couple of prints. While the filament is extruding I pull it out of the print head. I insert a .4mm needle into the nozzle to bring it back to original size. I then put the filament back in and complete the filament load. I have measured the extruded filament before and after diameter and the diameter gets larger after. I have found this directly corresponds to a better quality finish and better bonding.

    4. I modified the print head shroud to put a shield over the nozzle to isolate it from the fan, and installed high output double ball bearing fans. I do not know if this improves anything because I rarely go above 30% fan speed and have not set up a test to measure a difference.

    My conclusions are:

    To know whether or not any change is an improvement I have to do a before and after measurement. If I can not set up a measurement I can totally fool myself, as I have many times in the past.

    You have to have solve all of he problems before you can locate the one problem that is the most significant. I solved many problems that did not exist in this search.
     

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  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    :) It is easy to fall into a pit of our own reasoning. Good job getting it working better :)

    I try to remind myself of this:

    "For every problem there is a solution which is simple, clean and wrong.
    --Henry Louis Mencken"
     
  5. DavidR

    DavidR Member

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    This is the phenomenon you are referring to: Confirmation bias - Wikipedia

    Moisture tends to only be an issue with PLA over extended periods of time. With respect to brittleness, I have found that after each use and/or period in storage it will frequently just be the first foot and a half of the remaining quantity on the roll that is brittle. I just tear it off until I reach the point where its flexibility has returned.
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I bought one of these on-sale the other day (33% off) https://smile.amazon.com/gp/product/B08C9RF7R7
    and am trying it for giggles. I have not had issues with wet filament since drying the entire workshop, but I want to see how these perform since they may be a viable option for some folks. I'll test it over the next few days and see.
     
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  7. Lance Weston

    Lance Weston Active Member

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    I purchased two of them so far. I drilled and tapped the back of the boxes to accept pneumatic connectors so that my tubes which run straight to the print head ( I use 6mm OD / 4mm ID tubes on my printers) have no place for air to get in. The good: I can set the temp and it feeds well through the pneumatic coupler. The bad: They only run for 24hr without being reset, They have no moisture sensor or display, the rolls of plastic I use have very poor quality rolls with injection molding bumps on the edges. Those bumps will cause the roll to bind and must be filed off before use.

    I dampen a piece of paper towel with canola oil, wrap it around the filament then put a folder clamp over the paper as an oiler. This fits nicely in the box with the rear feed modification. This is a must to trap particles that get on the filament when filing the roll.
     
  8. RoboticsRob

    RoboticsRob Member

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    Just found this discussion and figured I'll chime in too, since I went through basically the same tribulations over the last few months, also on my independent but parallel goal of high consistency from the R2, as is Lance.

    Here's what I've settled on for my PETG print farm (I use almost exclusively Polymaker PETG, and I've actually never printed PLA) my print workshop is in San Diego near the coast, and likes to sit around 50% RH, until the Santa Ana winds come and drop it to 12% RH for a day or two:
    • Print Dry 2.0 with additional chamber kit - used to dry 4 spools of PETG at 75C for 10 hours
    • After drying, filament is either put into my dry storage boxes (Sterilite gasket bins with a healthy amount of silica and a hydrometer, typically sits around 15% RH in there) or into a Repbox 2.2 (acrylic, with seal kit and with all joints well siliconed). The Repbox typically reads about 18-22% RH
    I go through the spool in about 3 days (0.6mm nozzles) when I've got enough orders to keep the machines running, so the low 20% RH is plenty low enough for PETG, and since its significantly more hygroscopic than PLA, I can't imagine running into issues with PLA should I ever decide to get a spool and learn how to print with it.

    Up next on my list is TPU and Nylons. I'm confident I've got the humidity under control enough for TPU, though unsure on the Nylon storage. Anyone with experience there need to keep theirs any dryer, or should I just plan on keeping the Nylon actively dried throughout its use?

    Also worth noting that I've made quite a few 'tweaks' to my fleet of R2's:
    • Replaced all bearings in the X,Y motion system with higher quality THK/NSK bearings
    • Redesigned the bushing carriers and replaced all the X,Y bushings, and removed the tensioner spring from the assembly
    • Replaced the extruder with a BondTech BMG/Triangle Labs (I have some of both of them, and I really don't notice any differences in print quality)
    • I also use the plated copper nozzles that David mentioned above, for thermal conductivity
    • Better constrained the filament path within the print head by removing the molded filament path with Capricorn tubing
    • Added a heatsink and cooling fan to the extruder stepper
    • (Currently working on migrating to Klipper firmware and OctoDash - work in progress)
    • Soldered my V1 beds directly to the wiring harness and use a mix of Wham Bam flex plates and PartsBuilt flex plates, all with Wham Bam PEX
    • Added a support block to the z axis stepper
    I'll be tackling part the cooling system next, after finishing up my work moving to Klipper, but for now I use the PAFA fan duct upgrade from Robo3D and I never exceed 15% fan speed.
     
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If you store the nylon in a way that actively keeps it dry you should be fine. The reputable suppliers will make sure it is sealed dry an include desiccant to keep it that way.
     

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