Three-Spool Dry Box

thingiverse

Three-spool drybox and power supply module I designed because I wanted to be able to dry multiple rolls at a time, and my kitchen oven is gas-heated and won't actually dry filament. The box can easily reach and hold 60C to dry PETG filament if it uses the big distributor (and 120mm fan). The two-5015 fan small-distributor doesn't blow enough air and the box tops out at around 45C. The heater I chose has a built-in thermostat which shuts it off if the heater temperature gets too high, and with the small distributor the heater thermostat starts clicking off when the box gets to around 45C. I have not insulated the box at all. So far it works fine up to 60 C, and can probably go higher, but the surface of the box gets quite warm. It would work much better if insulated, and I can see wrapping something around the box to do this. The polypropylene of the box should not have any issues up to almost 100C, although many of the parts inside will have trouble getting so hot. I should point out that the heater is powered by 120VAC. This is dangerous to play around with, and all appropriate care must be taken to make sure all wiring is properly insulated. I have a fuse in my power supply box specifically to protect against a short-circuit, but this cannot be a substitute for good electrical practices. I have included three STEP files - one of the drybox assembly (with the big air distributor), one of the small air distributor by itself, and one of the power supply. I have also included STL files of all printed parts. --Drybox-- General design is that the filament spools roll on V-rollers with bearings - same concept as the TUSH. I have a heater and blower to warm the chamber to dry filament. There is room in the bottom of the tub to put dessicant packs (I used 50g packs so I didn't need a basket or anything), plus you can put dessicant inside the center bores of the spools if you desire. The heater is connected to a temperature control unit, and the fan is powered separately from the heater and simply left on whenever I'm using the heater. The box is a 21-quart Sterilite tub. I didn't use a sealed tub for mine, and just sealed up the lid and other holes with weatherstripping tape. It has stayed quite well sealed, but naturally a proper sealed tub will work better and not require the extra sealing steps. The spool holding assembly is two of the "fork" parts, which are attached to the bottom of the box. I used 5/16" threaded rods and nuts because I'm in the US and it's far cheaper and easier to get something that uses caveman units instead of a proper metric screw. The rods are each about 12" (305 mm) long. The nuts are used to pinch the bearings inside each V-roller. A 5/16" nut will squeeze the center races of the bearings very nicely and not hinder the rolling movement. Adjusting for different roll widths is just a matter of moving the nuts to adjust the roller positions. When I designed the envelope I was using Inland spools (Microcenter's in-house brand) which are 200mm in diameter and 68mm wide. There are two electrical feedthrough parts in the box. One is for the DC input module for the blower fan, and the other is for the power cable for the heater. A third penetration will be needed for temperature controller's sensor cable. I just drilled a circular hole and used a cable gland for that. I designed two distributors. These are each meant to take the flow from blowers, direct it upward, and diffuse it to blow over the heater. The small distributor is for a pair of 5015 blower fans while the large distributor is for a 120mm fan. I broke the large distributor into two parts so it would fit on my Ender 3 print bed. I simulated both distributors in CFD and they do a very good job of spreading the flow. I meant for this box to also serve as dry storage for filament while you're printing. There are three ports on the front for filament to come out. I designed two feedthrough types for these ports - each is meant for the pneumatic fittings used to hold Bowden tubes. The 6 mm feedthrough is for the small fittings which have M6 threads, and the 10 mm feedthrough is for the large fittings with M10 threads. Both feedthroughs are remixes of https://www.thingiverse.com/thing:4923697 and I've noticed that the M10 version allows filament to move much more freely than the M6 version - there's just more room for the filament to move. Both filament feedthrough parts have a groove for an O-ring if you want extra sealing. I sized them so that you can simply take TPU filament, snip to length, and use that - the grooves are 1.75mm wide. Another option for feeding filament to a printer directly from this box is to mount the box above the printer and drill holes in the bottom. There is room to do this, and I intend to do so eventually. The "humidity ring" part is to hold a common circular temperature/humidity meter. This part is optional but I've found it nice to have. --Power Supply-- The enclosure for the power supply is entirely printed - because I didn't want to buy and cut holes in a commercial box. It uses an Inkbird temperature controller. Power inlet is through a standard inlet module, and the power output is by a US-style outlet. A hole will need to be drilled for the Inkbird's temperature sensing cable, and I used a cable gland to strain-relieve the wire. I also connectorized the sensing cable with JST XH style connectors. The outlet is connected to the box using the screws which came with it, but they can be replaced with 3mm screws (and inserts) if desired. The only other addition I made to the power supply box was a 5A fuse - I'm using a 120V, 250W heater module which will draw about two amps, so the chances of blowing a fuse are pretty remote if everything's working. --Parts List-- The full assembly needs printed parts: 2 Forks 12 V-rollers 1 power feedthrough 1 fan feedthrough 1 heater support 1 Distributor (big or small) 1 humidity ring (optional) 1 control box 1 control box lid Purchased parts: 22 M3 screws, plus threaded inserts. 2 12" long 5/16" threaded rods (or ~300mm long 8mm threaded rods) 28 5/16" nuts (or 8 mm nuts) 12 608 bearings Tub - I used a 21-quart Sterilite non-sealed tub, but anything of similar size will work nicely 24V power supply - I used https://www.amazon.com/dp/B07VL8W6MQ?psc=1&ref=ppx_yo2_dt_b_product_details and used the little connector which came with it in my fan feedthrough. Temperature controller - I used https://www.amazon.com/dp/B00OXPE8U6?psc=1&ref=ppx_yo2_dt_b_product_details 120V AC heater - I used https://www.amazon.com/dp/B07G2DZBYK?psc=1&ref=ppx_yo2_dt_b_product_details Power inlet module - I used https://www.amazon.com/dp/B01N2T2N1W?psc=1&ref=ppx_yo2_dt_b_product_details AC outlet - I used https://www.amazon.com/dp/B0015R9M2Y?psc=1&ref=ppx_yo2_dt_b_product_details Cable glands - I used https://www.amazon.com/dp/B07JH2LPZF?psc=1&ref=ppx_yo2_dt_b_product_details Temperature/Humidity Sensor - I used https://www.amazon.com/dp/B07GR65CNT?psc=1&ref=ppx_yo2_dt_b_product_details Fans - either two 5015 blower fans or one 120mm blower fan I also used a standard computer-style power supply cable (for the power supply inlet) and a two-prong pigtail cable for the heater power (it plugs into the outlet on the power supply box). Also miscellaneous wires and crimp connectors for the various wiring connections. All parts that go inside the drybox were printed in PETG for temperature resistance. I printed the power supply box with PLA.