[insidous female companion says so] Need Dehydration Assistance

[Left Handed Spud Wrench]

Ok that insidious female companionship unit that associates with me has declared the kitchen NOT PART OF THE WORKSHOP.

This means no more storing chemicals in the fridge, the extruder-winder I built can't occupy the counter near the stove and the oven is not for curing resins, paints or drying material.



These are rolls of 3D printing material. The top is Flex TPE, the middle is generic ABS and the bottom is PLA. I have other kinds besides these, but this shows the maximum and minimum size of the rolls.

Basically all plastics (yes ALL OF THEM) interact with moisture in the air. Some collect surface moisture electrostatically, and others absorb it chemically. Plastic factories dry material before it is molded or extruded, or at least the ones that aren't run by morons do. I've been in a few that don't and the excuses are hilarious.

Anyway I digress! The insidious female companionship unit says why not get a food dehydrator and put the rolls in there. Or some other kind of small oven.

I'm looking at Craigslist and I see a few of both. There are a a couple food-dehydrators that look like they can hold a roll or two just fine, question is how hot do they get? I typically dry my materials in the oven at 120-180 for several hours and keep a close eye on that with a thermometer. Can the typical food-dehydrator be dialed in to that temperature and hold it for 8-12 hours without fail? Or should I be looking at (for example) a small bread oven or warming oven from a restaurant-fixture sale?

Keep in mind the workshop space has 120 volts (can't use the 220 because that's for the dryer, she's RELENTLESS I tell you) nor can I pipe gas into the living room (which is also my workshop.)

So... ideas?

[boslab]

You want a laboratory drying oven ( I used to put nylon 6 or was it 6.6? Granules on trays in one for injection moulding) they can stay on 24/7 and have a chimney to allow soggy air out, you could keep a roll in a big desiccator after drying as the silica gel will suck up the water, the silica gel can also be recycled in the drying oven
Old stock pots with a good pile of silica gel in the bottom are handy to store filament, cheaper than glass chambers, not as good but serviceable, the pressure cooker is the best, good rubber seal
Mark

[Left Handed Spud Wrench]

Great idea on the pressure-cooker for storage. I need a solution for baking down rolls that have already sat out. Certain materials won't give up their moisture without heat so silica-gel won't help there.

Typical factory-type drying systems take air, heat it, run it through desiccant and then blow that through the material to carry away moisture. Takes several hours. I don't have the option of building or buying a desiccant drying system yet, the convection oven in the kitchen worked just fine for what I was doing.

Hence, I am looking for something small that I can put on a bench or out of the way.

[J Tiers]

This sounds similar to the welding rod drying problem.

So, what would be wrong with a metal box inside another one, with a couple old-fashioned light bulbs in the space between at the bottom?

Should keep the inner box (or the only box, if you leave off the outer one) warmer than the rest of the environment, and so would tend to drive off the moisture from whatever is kept warm inside.

A bit of insulation around the inner (or only) box would keep it from getting cooled off too much.

You could just leave the stuff in there, depending on how much you have, and how big you can tolerate.

[Paul Alciatore]

I have to agree. I might use a couple of resistors instead of light bulbs. I once fixed the pot warming element in a coffee maker that way. The light bulbs will eventually burn out but resistors will last a long time if they are generously overrated.

10 or 20 Watts should be fairly safe. P = V^2 / R or R = V^2 / P
R = 115^2 / 15 = 881 Ohms

And use a 25 Watt resistor. Or two 10 Watt ones in series or parallel. Two 500 Ohm in series or two 1500 Ohm ones in parallel. Either should work with 115 VAC.

Just one possibility:

http://www.mouser.com/ProductDetail/ARCOL-Ohmite/HS15-1K5-F/?qs=sGAEpiMZZMtlubZbdhIBIEidPY%252bx%2fLaaeVq7PqzE2C0%3d

If you really want to get fancy, add a thermostat.

This sounds similar to the welding rod drying problem.

So, what would be wrong with a metal box inside another one, with a couple old-fashioned light bulbs in the space between at the bottom?

Should keep the inner box (or the only box, if you leave off the outer one) warmer than the rest of the environment, and so would tend to drive off the moisture from whatever is kept warm inside.

A bit of insulation around the inner (or only) box would keep it from getting cooled off too much.

You could just leave the stuff in there, depending on how much you have, and how big you can tolerate.

[darryl]

What about those coffee cup warmers- I wonder how much power they use (and dissipate as heat). You might put one in a box of some kind, along with an oven thermometer and a dimmer switch. For a box how about a scrap microwave oven- already has an inner chamber, power cord, sometimes some insulation, room for the cup warmer where the motor for the rotating plate is, and a door you can see through. Scrap everything you don't need.

[flylo]

How about a toaster oven or a food warmer likr used to cater?

[Rosco-P]

Compact sized fridge (dorm size) and add a small heating element from a gun safe or a couple of small wattage light bulbs in series inside it.

[1-800miner]

Have you considered a new insidious female companion?

[A.K. Boomer]

So... ideas?

She leaves you no choice --- get rid of the gurl, do it nicely - you never know when you might need her again,

right now I got an OHC weed eater engine sitting on my kitchen table that I fire up when guests come over, try doing that with a kitchen nazi in the vicinity...

[boslab]

What I was trying to say was dry in the oven then store in the container, as you say desiccant like silica gel won't pull out locked water, it stays until heated, great if you want a moulding like an aero bar I suppose, even bending Perspex and polycarbonate without drying you end up with a bubbly mess with steam bubbles.
There are other materials you can use in a desiccator, copper sulphate is good, it's blue when water of crystallisation present, cook it and it goes quite white and drags in water like a camel
We had one oven that was inert gas purge, bottled gas generally has no water in, purging forced the moist air out of the oven, air however carries water well, how much depends on those nasty steam tables, delta this, entropy blah blah, not my favourite book!
Also if you heat a pressure cooker the air inside expands, when it cools you get a partial vacuum so even less H2O in there
Mark

[vincemulhollon]

right now I got an OHC weed eater engine sitting on my kitchen table that I fire up when guests come over, try doing that with a kitchen nazi in the vicinity...

Not necessarily wrong, just saying the real professionals fire up a leaf blower to clean house before guests come over.

Something to consider is I checked online and the dew point where both OP and I live is approx 34F today. My PLA prints look normal, no different than in the summer during 75F dew points. So different plastic might be a good idea.

I've begun to believe that the proverbial "steam bubble" stuff that people report with cheap filament is simple air bubbles that get heated, expand, pop, and make a mess of the print. OR there's some contaminant in cheap filament that is a million times more hygroscopic than bulk PLA. Perhaps the pigment. I mostly print with hatchbox products; I'm well aware there's cheaper filament, and I absolutely no not want the hassles of cheaper filament. Its only like 10% more expensive than the cheapest stuff anyway, practically a rounding error. I store my medium-high quality PLA in a filing cabinet in an office-like environment and I just don't get steam blowouts like I've seen pix of online.

I have bought cheap no-name filament and run into trouble with bed adhesion. Also some of the cheap filaments literally smell different than the almost odorless good stuff, which surely cannot be good.

[RichardG]

Why not an old fridge with a light bulb and some silca gel just have to size the bulb worked great for welding rod over the years.
Richard

[J Tiers]

....

I have bought cheap no-name filament and run into trouble with bed adhesion. Also some of the cheap filaments literally smell different than the almost odorless good stuff, which surely cannot be good.

It's cheap, a commodity, has no brand name, and it comes from china. Is there more information than that needed to define a risk?

An office environment is air conditioned, and usually fairly low humidity. Not comparable to the shop.

Like I said... light bulbs and a box may be all that is needed.

[Forrest Addy]

Toaster oven calibrated by thermometer? Mine sticks pretty close to set temp but I foil wrap the target goody to mitigate radiant heat overshoot..

Desiccant pouch and plastic rolls in a baggie?