DIY Filament Dryer Box 120v

Update: added a 7530 option.  Because reasons.

I have been getting into Nylon, PC, ASA, and ABS printing and I needed a way to dry my filament.  I had been using a modified food dehydrator for years and I noticed that it wasn't really doing a very good job.  I determined that it was only capable of reaching about 50c (20c lower than it's advertised max temperature of 70c) and no amount of tinkering was able to rectify this issue.  So I went looking for an alternative.  I was not impressed with the commercially available filament driers I found.  I stumbled upon Pslaughter's design.  I printed it out, but I found that the box I had available really was not big enough to put the heater unit and the spools in at the same time (read: I melted a spool because the hot air was blowing directly on it).  I also did not have good luck with the many heatset inserts in that design and determined to do away with them.  I also wanted something that could be built into the box and have it basically be an appliance.

You will need:

• 120v 500w PTC heater element https://www.amazon.com/gp/product/B07P5NCR2F
  • Note: 500w is only enough if you are recirculating the air within the drybox.  If you are using only fresh outside air, your max temperature will be severely limited.
• 120v 120x32mm fan https://www.amazon.com/dp/B07WT275SC
  • This model was my preference since I don't believe that speed control on the fan adds any value in this application.  If you get one with speed control, obviously you don't wire it to the temperature controller (since it's actually a 12v fan most likely)
  • You can use the AC plug from this fan… but the switch on it really sucks and may fail on you.
• Or a 75x30 fan
• Aluminized heat shield (about 4 square feet (12x48) https://www.amazon.com/dp/B0CXX7CKM4
  • Maybe buy an extra roll of this… You will use two 1"/25mm strips to protect the heater holder and the rest of it to protect the inside of the box from the hot air being blown on it.
• 120v Temperature controller. I've had good luck with Inkbird; but there are plenty of other options. https://www.amazon.com/dp/B0152LYY0I
• Some M4 hardware.  The fan should come with screws long enough to mount it.  You need 4x M4 nuts to press into the plenum and 4x M4x16-20mm bolts to mount the heater and plenum to the side of the box.
• A flat sided box with a lid in the 18-25L range.  The one I used is about 12x17x10 (LxWxH).  Most spools are ~8" in diameter. Try to choose one with thick clear sides.  This one is popular in the community, but is not the one I used… https://www.homedepot.com/p/Ezy-Storage-18L-19Qt-Waterproof-Clear-Latch-Tote-IP-67-FBA34060/314650516 
• One scrap piece of 16-20awg wire 3-4" long to use as a jumper on the temperature controller.  More if you want to extend the wires for the heater and/or fan.

Remarks

If you are in a 220-240v country, you will want to adjust the heater/fan/temp controller to take account of that fact.

Filament choice - ABS/ASA or better.  PETG, PLA, PLA+ are not good enough - they will melt.

• I also included a printable placard with recommended temperatures and drying times.  Color change at layer 8.

Print your parts flat on the bed in an orientation that does not require supports.

Print an enclosure for your temperature controller - exposed 120v isn't good.  May I humbly suggest my model https://www.printables.com/model/899566-temperature-controller-box-for-inkbird-and-clones 

I stand 4 spools in the dryer box and hang the temperature sensor on one of the spools on the hot side.  Make sure your temperature sensor ends up inside the enclosure and not blocked by heat shielding.

Instructions:

Hardware Installation

1. Press the M4 nuts into the holes provided in the plenum - use a M4 bolt to help seat them.
2. Cut your strips of heat shield for the heater holder, peel the adhesive mask, and apply.
3. Mark the holes for the plenum and heater assembly (but not the fan yet).
4. Mark the mounting holes by placing the fan in the plenum and putting it where you want on the outside of the box and transferring the hole locations with a sharpie.
5. Use the template to find the mounting holes you transferred and trace the inside to transfer the air hole.
6. Cut the holes in the box for the plenum/heater assembly (but not the fan yet!).
7. Drill holes (¼" drill bit) and cut out the air hole with your tool of choice.  I used a dremel with a little saw blade.  Drilling corner holes and using a hack saw blade might also work.
8. Once your first holes are cut, bolt the heater, heater holder, and recirculating plenum to the side of the box - don't tighten the top bolts yet.  If you feel the need, you can use the template spacer inside the box to space the heater off from the side more.  I did not use it on mine and it's been okay so far.
9. Insert the fan into the hole in the plenum with the intake facing the side of the box (remember, it's going to be recirculating) and trace the mounting holes for the fan and a circle (or slots) for the fan intake.  Go drill the holes and cut the fan intake out.  A hole saw makes this easy, but you can do it other ways.
10. Also drill a hole to pass wires from inside the box to outside.
11. Insert the fan and bolt it down.  Tighten the top bolts on the plenum.  The intake grill is optional, but it makes Prudence - The Safety Goat® happier if you do.
12. Install the heat shielding in your enclosure box.  The wall that the heater is facing is critical.  I did all four walls and the floor.  I did not peel the adhesive masking for the heat shielding on anything besides the heater holder.

Wiring

Please see attached wiring diagram for the temperature controller I used.  If you use a different temperature controller, please consult the wiring diagram for that controller as it may be different.  We're using 120v wall current here, so get it right.  If you're confused, this isn't a good thing to get wrong.

1. Insert the temp sensor into its terminals (Terminals #3 and #4).  It is not polarity sensitive. Tighten the terminals down now.
2. Wire 120v AC power to the input on the temp controller. L is on the outside (T#1), N is on the inside (T#2).
3. Wire the 120v fan directly to both of these inputs so it will be “always on” as long as the controller has power.
4. Following the diagram, insert one end of the jumper into the L AC input T#1 (closest to the outside of the unit).
5. Wire one side of the heater to the N AC input T#2 (closest to the middle of the unit)
6. Wire the other side of the jumper to the non-switched side of the heat relay T#5.
7. Wire the other side of the heater to the switched side of the heat relay T#6.

Just in case this is clearer, here is what goes in each terminal:

T#1 - Line, jumper, fan

T#2 - Neutral, fan, heater

T#3 - Sensor

T#4 - Sensor

T#5 - jumper

T#6 - heater

T#7&8 - empty

Note: Be wary of stray wires sticking out of the terminals.  Wall current is no joke and house fires aren't funny.  Tighten the terminals and CHECK that you can't pull any of the wires out by tugging on them.  Your life depends on them being tightened correctly.  You are responsible for this device being safe to operate.  Do not leave it plugged in unattended.   

Acknowledgement

This is heavily influenced by Pslaughter's design.  And, although it shares no printed parts in common, I thank him for his idea and advice.

https://www.printables.com/model/882803-120v-filament-dryerchamber-heater