I've been messing around a fair amount with the 3D printer that my wonderful wife gave me for Christmas last year, so here's a post about that. The printer is a Qidi Tech I, and it's been a mixed bag... when it works it's a huge amount of fun, but when it doesn't work the troubleshooting is frustrating.
The good part of the printer is that it has some cool features (dual extruder, fully enclosed) for a really cheap price because it's a Chinese knock-off of a knock-off of a MakerBot Replicator 2X. Here's a review to give you the idea... my nephew recommended it to my wife and I can see why he did. But like I said it takes some trial and error to get it to work well, and one of the problems I was seeing is that sometimes the filament would break. A friend of mine suggested that the problem could be moisture and I should be sure to keep my filament dry. A good solution is a "dry box" — an enclosure for storing the filament with a really low internal humidity.
You can buy a dry box if you want, but I preferred to build my own partly so I could customize it and partly just for fun. Others have written some great articles about DIY dry boxes that they made, like Becky Stern's article (Becky is awesome, she used to be with Adafruit and now she's at Instructables), this one on a web site called 3dprintingforbeginners.com, and an interesting post by Tyler Koslow.
I took a mixture of ideas from them, and started by going to the Container Store (because I happen to have a location nearby) and selected a "46 qt. Weathertight Tote Clear". It's got a very nice water-proof seal around the lid.
To turn it into a dry box, it needs a few mods:
- Something to hold the filament up and let it unspool
- Desiccant to keep it dry
- Hydrometer to see how well the aforementioned desiccant is doing
- Ports through which the filament can leave the box
- Tubes to carry the filament to the printer
- Brackets to keep the aforementioned tubes organized
Here we go, one by one.
1. Something to hold the filament
I liked Becky's method of using a PVC pipe for an axle and 3D-printing some brackets to hold it up. I designed my own brackets [Thingiverse], which are just a remix of the design she linked to. I adjusted for the size of my pipe, and added countersunk slots for the M3 hex nuts.
In the 46-quart box, there's room to hold 5 1kg spools. I printed them in PLA, drilled two holes in each side of the box for the M3 bolts, and attached the brackets. I cut the PLA with a hand-saw to fit the length of the box and dropped it in.
2. Desiccant
An air-tight box doesn't help much if you don't reduce the humidity inside. For that crucial function, I chose an Eva-dry E-333 renewable dehumidifier. If it gets full of moisture, you can take it out of the box & plug it in to a wall socket, and it'll restore itself for another round of humidity fighting.
3. Hydrometer
To measure how much moisture is actually present in my dry box, I again turned to Amazon (see a pattern? :). The "EEEKit 2-Pack Mini LCD Digital Electronic Temperature Humidity Meter" is cheap, and because it's a package of two I can compare the humidity inside and outside of my box. The humidity in the room averages around 45%, and inside my box it's around 10%. I guess that's good enough, I don't know. Seems pretty nice and low to me — I guess the Eva-dry does it's job.
4. Filament Ports
The box needs holes for the filament to go out of. Although I liked the 3D-printed "screwless filament feeders" that Becky decided to use, I decided to buy some professional-looking 1/8" PT Male Push in Joint Pneumatic Connector Quick Fittings. I drilled holes in my box, screwed them in, and pushed the tubes into them. Easy.
5. Filament Tubes
The tubes to protect the filament from moisture in the room while it's traveling to the printer are made from PTFE. I picked 4mm ID PTFE tube because it fits my printer. I wanted to run 5 separate tubes to make it easier to switch filament, so I bought 25 feet of tube. This part is perhaps over-engineered, but fun. Here's what it looks like, hooked up:
6. Tube Brackets
At this point my dry box was functional, but unwieldy because when tubes weren't connected to the printer there was nothing to keep them organized — they'd flop all over the place. To solve that, I printed some brackets to hold the tubes in place. One bracket went on the printer, one bracket went on the wire shelf that the printer sits on, and one bracket holds the ends of the tubes and serves to "cap" them so that no moisture can creep in the ends. The bracket on the back of the printer looks like this:
The Qidi Tech I has four little M3-size holes there, so I printed little legs that connected to them. And then those legs attach to a pair of plates that work kind of like a waffle iron to hold the five tubes in place; the top and bottom plates are held together by a pair of screws on the sides [Thingiverse]. To hold the legs on I used a technique that I'm surprised isn't more popular because I find it works very well: you can glue PLA parts together using "Weld-On 4 Acrylic Adhesive" [Amazon]. Although it's normally used with acrylic (as the title of the product suggests) it seems to work very well on 3D-printed PLA too. To line up the parts properly, I modelled little pegs on the leg parts and matching holes on the back plate. The adhesive won't benefit from capillary action the way it does with the smooth surface of acrylic, so you just use it like regular glue and squirt a little on one part before placing the other part on top. No clamping necessary, as long as the parts will stay in place by themselves.
The bracket to feed the tubes through the shelf was constructed a little differently [Thingiverse]. It has just two pieces that fit tightly between shelf wires and push against the wires to hold the tubes in place. Again, M3 screws to hold the two halves together.
Finally, I'm obviously not using all five tubes at a time and I don't want them dangling around loose or allowing moisture to come in the open end. So I printed one more bracket, a little block [Thingiverse] that has five closed holes for the ends of the tubes to stick into when I'm not using them. I wanted to attach this to the bottom of the shelf above the printer, and instead of screws this time I modelled slots for two zip-ties to hold the block in place. There are grooves on the top for the shelf wires to fit into, and then the zip-ties pass over the top of the shelf wires. It's a crowded environment because the underside of the shelf is where I run wires too, but here's my attempt at a photo. The lime-green things are the zip-ties.
Here's the finshed product, sitting neatly on the shelf underneath the printer.
Questions or comments? Email me at .
2018 Nov 21