Dessicator For plastic storage.

Im curious if anyone knows of a way to get an ultra low humidity chamber that isnt too expensive , Ideally somthing around 2-3% Relative humidity. So far my only idea is a peltier unit unside a chamber, maybe use an old bar fridge as it should be reasonably air tight and large enough to store a few rolls of plastic.

I know that industrially, with dry enough nylon they can reliably achive 0.001" extrusion. I understand this cant be done with abs but if we can get dry enough nylon and have a hot end with a short enough tranistion zone and say a 0.1 mm nozzel extremly high resolutions are possible.

PC is also known to absorb alot of water so for reliability reasons storing it in very low humidity might have some advantages.

Here is a box a Tantillus user created to keep his filament dry. [www.forums.reprap.org] It uses a low wattage light bulb to keep the temp inside the box higher than ambient.

Edited 1 time(s). Last edit at 07/07/2013 08:37PM by Sublime.

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Iv seen this before and not sure what to think. On the plus side im sure it works and that it is a viable solution for most applications.

On the thread they mentioned 30-40% RH which is considerably higher then the range id like to experiment with.

Steven

do you just want to store it in the box or feed out of it.?

I was thinking storing. Im just not sure how to go about it.

The following calculator has me thinking : [andrew.rsmas.miami.edu]

Say timperatur is 25C and RH is 3%
Dew point is reached at -23 which might not be impossible with a peltier with a very small heat sink (if any) on the cold side and a very large one on the hot side , thoughts ?

i think your gonna be better off with a chemical decasent i think, i am trying to remember what the difference that peltier can achieve, if you wanted to go that rout i think one of the plugin coolers would be the way to go.

you might find this handy, they might just get cooler than i thought https://www.sparkfun.com/products/10080

I bought some ammo cans off ebay. I use a small toaster oven set on low (my oven is very accurate unlike most) to dry out the nylon then store in the ammo cans that are air/water tight.

I have thought about just buying some bulk desiccant beads and pouring them over the rolls in the ammo cans. You can get the stuff in gallon and 5 gallon cans not too expensive. This is how they preserve flowers and insects.

tmorris9: I assume your talking about sillica dessicant THe problem with this stuff is that it doesnt absorb much water, This is especially true when trying to maintan very low humidity.

See :[www.sorbentsystems.com]

So if our goal is say 5% RH you can only use about 5% of its absorption capabilities. This means you need 20 times the amount of dessicant.

Last night i ordered a peltier unit 40mm x 40mm advertised as 130W. Going to play with it and see what I can come up with.

you can even run the pelt at lower temps like 5v, and it still gets quite cold.

Don't forget to add a heat sink to the hot side along with a fan or it can destroy itself rather quickly. I make coolers for epoxy with peltier