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Optimal RH%

Discussion in 'General Questions' started by Lance Weston, Oct 24, 2021.

  1. Lance Weston

    Lance Weston Active Member

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    I have modified a couple of Sunlu Dryer boxes to regulate both temp and RH. If both the RH is too high and the temp is too low then the heater turns on.

    I loaded a new roll and started printing at an RH of 40%. I set the box to bring the RH% down to 15%. As I started printing I could see some improvement in finish quality over the first two days. Now the Indicator strip in the box indicates that I got down to 10% RH and my print quality seems not to be as good.

    What is the optimal RH% for printing PLA?
     
  2. Jerome Helbert

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    I have two large 82 quart airtight containers that I store all of my filament in, as well as several two dryboxs that I can print directly from that are based off of cereal containers. I have a large amount of desiccant in them all (probably way more than is necessary, but I have to refresh it considerably less often.

    According to the sensors I keep in each of them, I run 1-2% RH in all of them (the sensor has +/- 5% accuracy below 10% RH, but it's so low it's probably in the ballpark. I have zero issues with print quality. I have them mostly for print polycarbonate and nylon, but use them for all my filaments now and have never noticed an issue.
    Capture.PNG

    I've always assumed lower is better.
     
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  3. Lance Weston

    Lance Weston Active Member

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    There are so many variables and I tend to think the thing changed is responsible. I have to get this installed on a few printers to see if I am fooling myself. My current method was to take a spool, load it in and save parts every 12 hours as the RH% went down. I then compared finish on the parts which is pretty subjective. I found that 20%RH was the best finish for PLA. I will repeat this over many rolls and see if it repeatable. Thanks for your info..
     

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