Multi Spool Filament holder/dryer

thingiverse

<H3><b>Another filament spool holder/dryer</b></H3> <u><b>Updates:</b></u> <b>04/04/2022</b> I have had the dryer running continuously for the last few days, monitoring the temps and humidity. It appears to be working fine but I am not happy with the temperature variation that occurs inside the enclosure. I have 3 different sensors in different locations inside the enclosure (bin) and the temps can vary as much as 10 degrees. I am also wanting to incorporate the desiccant tray idea and see if I can improve the efficiency of the unit by providing some trays and baffles that would distribute the heat more evenly and allow a lower humidity at a lower temperature. Because of this I am having to alter the end frames in order to provide some extra clearance for the spools and lower the bin placement a little. I believe I need to close up the openings under the bin along the outer sides in order to maintain a slightly higher temperature. I could do this by cutting a frame the holds the bin and sits on the aluminum supports, however, I also want to add a metal screen between the bottom air chamber and the spool area. The current design does not provide quite enough clearance at the base for a flat screen to fit so I am redesigning so the spools will ride slightly higher inside the upper enclosure. I will update the files when I have a design ready for testing. <b>01/04/2022</b> Not really an update, but I was thinking about the concept of metal desiccant trays and thought that using several smaller ones would make it easier to swap desiccant in and out of the unit. I have added a sample picture of a smaller, sheet metal tray. 3 of these would be used in a frame that would fit the Sterelite Gasket box I used (about 300mm long.) They would slide under the aluminum square rods from the front and should not interfere with the filament. The back and front of the trays would act as the dryer walls and the higher inside wall with the holes would help deflect the hot air away from the blank end stand. I marked the example with 100x150 but really it should be closer to 90x150 since 300mm is the distance between the outside of the end stands. <b>31/03/2022</b> With the new end in place I figured I should increase the temps to see if it would be an issue. I also decided I should be making a comparison of %RH to the current room temp so I added that information to my graph. Blue and Red are the Dryer and Green and Yellow are the room numbers. As an additional change, I added a piece of right angle flashing, placed near the middle of the bin, on the floor of the enclosure. I thought that by blocking the direct air flow on the end plastic and directing it upwards it would decrease the high temps on the End Frame and decrease the chances of that piece deforming. I'll have to wait to see what impact it has. I expect that by using this baffle it would negate the need to provide a cover attached to the end stand, making it a simpler fix. I added a (bad) picture that shows this. Those are small sacks of desiccant on either side of it. With the dryer temp set at 40C it appeared that the %RH stabilized around 19% By increasing the temp to 45C it looks like the %RH dropped to under 15% and is remaining relatively stable at that level. If the mass of the spools and filament is too much for the end piece to hold when temperatures are high I expect that an upper simple support piece could be used for additional strength. If this was not enough I will have to look at how I could add a vertical support piece, using a material other than plastic (maybe a short piece of aluminum,) to add a rigid support (for the spool pipe) that can't distort under the load. <b>30/03/2022</b> I have added a version 2.2 of the Spool Frame parts that are heavier duty. I found that the PETG I was using was not as rigid as some of the other PETG I have and when kept at even 40C for several days would soften enough to distort under load (1-2 kg). I could have added an addition single support piece in the centre to offset some of the load but decided to try and strengthen the basic design. The issue only appears to be happening on the blank end where the structure gets the direct heat from the fan. The fan end does not appear to get soft but may if the enclosure temps were pushed up. I still have to test out these new ends to see if they solve the problem. I don't think there is any issue with the original parts if not using the heater components. <u><b>Summary:</b></u> <b>Background</b> I have a PrintDry system which is essentially a food dehydrator that fits a couple of filament spools (horizontally) and allows printing while drying. I noticed that the unit appears to run constantly so I decided to compare the inside temps using the temp control knob. I found that the temp settings on the device made no difference and that it was always running around 65 degrees C. It appeared to work fine at that temp so I was not too worried about it. I also found that when using full spools, sometimes the wraps would slip off the bottom and get tangled. Again, this was not too much of an issue as I could use small clips to keep this from happening. My biggest issue was placing the device in a location for my Predator (top feed) so that the filament feed did not have to make a sharp bend. This was more of a space issue that I couldn't resolve. Because of all these issues I decided to look into a better design for my use and eventually came up with this. <b>Basic Spool Holder</b> The simple filament spool allows me to place as many spools on the spooler as I like. It is basically a couple of end stands that hold a 1.25" ABS black plastic pipe. It can also hold other smaller sized pipes or dowels such as a 1" PVC pipe. You can even use the wand from the vacuum cleaner. The end stands are connected using two pieces of aluminum deck rail which I already had, but other materials can also be used for this such as rectangular wood pieces or dowels or by screwing the pieces to a flat base. I did not provide holes for this but it would be a simple change to do this. I use two end pieces and a piece of pipe about 30cm long as this fits nicely into my sealed Sterilite gasket dry boxes. If more spools are required additional support pieces can be used if there is a span issue with the additional mass of the extra spools. <b>Filament Dryer</b> Since I generally leave my spool attached to my printer for days and our relative humidity is on average around 40 to 50% inside I would prefer to protect the open filament spool. As an option the Simple support ends can be replaced with the larger ends that raise the filament higher and allows the addition of a PTC heater and fan unit. These parts can be purchased for about $30. I use a 110V version with a 110v AC fan instead of the 12 or 24 v DC fans that come with them. You can use the lower voltage DC versions if you prefer but be aware that they require a pretty hefty DC power supply. <b>Temperature Controllers</b> I use a STC-1000 (temp only) or STC-3028 (temp and humidity) unit to control the heater. These devices have built in relays that can be used to control the heater and/or fan units and can use the same source power as the controller or a different power source. They cost about $10-$20 An alternate method of controlling the heater would be to use something like a sonoff wireless temp gauge like the SNZB-02 and a smart switch for controlling the heater power. I have not used these in this situation but if the sensor refreshes often enough, it could work. I have one of these sensors inside the box so I can use the data in my HomeAssistant setup. I hate messy wires so I designed the end piece for the fan to hold a couple of compact wire connectors and have a cover to protect any exposed wires. The power control box is an external unit that can be placed as needed. It would connect to the heater with a lamp cord style wire of high enough gauge to handle the load of the heater. If you went the wireless sensor route you wouldn't need this setup. The smart switch would be the power controller. <b>Enclosure</b> To keep the heat contained within the base of the unit I designed some small, clip-on walls but this can also be accomplished using some thin wood or some plexi sheets. The cover for the unit is just one of my sterilite bins placed over the top. It should probably have some holes drilled in the bottom but I didn't want to damage the bins I had so I'll find a cheap alternative that I can do that to. I believe that in order to obtain lower %RH the unit should be vented on the top to allow the moister air to escape and be replaced with dryer air otherwise the moisture just keeps building up in the trapped hot air. <b>Testing</b> Currently my tests are showing that if I set my temperature to around 50 C the enclosure is maintaining around a 16-20% relative humidity with a 40% relative humidity in the room. The % varies quite a bit (begins to rise again) which I think is due to not venting out the top. I'll have to test again once I cut some vents in one of my bins. I have included a blank end as well as one that can have a fan attached to if you wanted to set up some kind of venting. I think passive venting is probably the best but it requires holes in the top of the enclosure. The fan end could also be used if you were supplying your heated air from a different source, than the PTC heaters I used, or just to purge the saturated air more quickly from the enclosure. It could be wired to the Cool relay on the STC controllers. I ended up drilling about 14 holes along the bottom chamfer of one of my bins. I then ran some tests at 40C to see what impact they would have. I decided to keep the temp low as my intent for the dryer is actually a low humidity spool holder/feeder. I also wanted to ensure that the spool holders were not impacted by excessive heat. I did include a small metal shield (pop can) on the end wall. My room humidity started at around 45% and once the heater started the %RH dropped a lot. It then continued to slowly drop over time while the temp remained at 40C. After about 18 hours the %RH had gone down slowly but steadily to around 18% <b>Electronics Case</b> I designed an enclosure for the STC controller so it can have an AC power switch and computer styled power cord. There are a couple of lengths. The 120mm should work fine but if the wires are too difficult to handle you can always use the 150mm case instead. I did not cut the side holes (top/bottom pieces) all the way through as I found they made the ends of the print sloppy. Instead there are indents where the holes go. Just drill out with a 3mm drill. The front and back ends are slightly smaller holes so nuts should not be required. The back of the unit has a couple of small hole for feeding the probe and heater wires through. I made these blind holes so you use a sharp blade and cut open the one you want depending on the probes and wires you are using. The switched plug should use nuts on the retaining bolts as removing the plug requires quite a bit of force. I believe the 120v heater draws about 300w so a short piece of lamp wire should be adequate for connecting the control box to the heater. Make sure you check the load of whatever unit you use to ensure your wires are large enough. If I had any AC panel sockets lying around I would have made the box slightly larger and used one of those for attaching the heater/fan unit with a regular AC plug. It would make the control box easier to use for other applications. I may still add an alternate design if I get time. <b>Desiccant drying</b> I can place my desiccant into the unit as well to dry it for reuse. A small tray could easily be slid into the base of the unit for drying desiccant. I currently have a couple of small mesh bags full of desiccant that I just drop into the base of the unit. They appear to dry out fine. If you wanted to get fancy you could bend up some aluminum flashing into a tray with tall side walls that could act as a desiccant drying tray and act as the side walls for the enclosure all in single unit. I added a picture as an example. <b>Filament and warping issues</b> I printed mine in PETG but I think ABS would be a better choice. PLA may be too soft when the temps inside go up. My Blank End Frame test piece only had a 1mm wall and no support walls. This part (thin wall) would warp when running around 50 degrees. I didn't notice any impact on the actual spool support but I only had about 1kg of load on it. The actual piece has a 2mm wall and a couple of thicker supports which may be sufficient. I also added some screw holes to the blank end in case you want to add a metal shield inside, since the heater fan blows directly at this wall. Probably a piece of thin aluminum flashing or something like the aluminum from a pop can could but cut to fit and fastened onto the inside just to block the direct hot air from hitting the plastic end. That foil tape for HVAC/ducting might work as well. If I notice warping of the structural supports with heating I can always add some extra supports in that area. <b>Materials</b> spool holder: 1.25" ABS pipe (or similar) rails: 2 lengths of 19x19mm aluminum square tubing (deck rail or alternative) heater: PTC heater and fan (use appropriate voltages for heater and fan) https://www.amazon.ca/dp/B07NY18B6Z/ref=cm_sw_em_r_mt_dp_A4RHJ31DW17HR31791TS?_encoding=UTF8&psc=1 temp controller: STC 1000 or 3028 wire clips: Wago 222 or similar switched plug: Fused, switched 3 Pin Male Power Socket https://www.aliexpress.com/item/32829721845.html?spm=a2g0o.order_list.0.0.21ef1802OCZpXE Enclosure: Sterelite 19L gasket box (or similar)