Now that my AXIS is no longer in a workable condition I thought I would try to repupose the parts from the printer into something usable.
This past weekend I built a dry box for my filament. I took the glass that I purchased for the AXIS bed and used it as a platform. Under the glass I attached a reptile heating pad. This platform set off the base of a gasket sealed 54L plastic box. I poured about 1kg of desiccant in the bottom and added a hydrometer and thermometer.
I had hoped that the reptile pad would heat up more than the 28C.
To build the box I also used the couplers that came with the dual extrusion upgrade for the printer.
While I was admiring my handiwork I thought, "wouldn't it be awesome if I took the heated bed, mosfet, and 24v power supply and replaced the reptile pad with it instead?!" I figure if I could do that then I could get to ~50-60C. This wouldn't be a dry box but a drier!
So, here's where I am. I have the heated bed. It will attach to the mosfet control like it is in the printer. I'll get an Arduino Uno, a digital encoder, and a LCD display (or better yet the LCD and encoder from the printer). Next, I'll make a little case that holds the Arduino and the display and mount it in a box. The thermistor will run to the Arduino and work the PID temperature control code based on the control. I can reuse the barrel connection to connect the 24v to the mosfet board. The Arduino should be able to send a PWM signal to it.
I'm not the best at this stuff. I'd really be interested in getting some help and then writing up an instructable!
I gave up using the Arduino and ordered an STC-1000 controller from Amazon. I used the power supply and the mosfet to power and control the feed to the bed. I disassembled the external Mean Well power supply that I built and used the cord plug to provide the 110 to the STC-1000.
Precarious setup with 110v just hanging out...
I assembled it all into one of the air-tight boxes I purchased to store filament.
The STC-100 uses a NTC 10K thermistor. I tried hooking up the thermistor that's in the bed. That thermistor is an NTC 100K. It messed up the reading drastically. At some point I'm going to order a different 10K thermistor and replace the one in the bed so I can get a better reading. This is sufficient for the moment since the degree of accuracy isn't as important in this case.
As shown above, the assembly seemed to be wasting a lot of heat. I had some styrofoam type insulation around so I did my best to cut it and fit it in the box.
The reading at the top shows ~97F with 29% RH. The humidity outside of the box was in the low 60's. This is with the bed temp set to 60C. I need to do some better work on insulation. Turning the bed to 70C allowed me to get to ~105F/40C. I really need to get another 10-20C for better drying. Ideally I'd like to be able to keep it at 50C for PLA and up to 60C for nylon (which I've been waiting to try till I can get this working).
As seen I put in two rolls of filament. The larger roll is some Tecbears PLA that I've had for a couple of months. The smaller roll is the red PLA received with the AXIS kit. The black had started having a pop every now and again and the layer adhesion was starting to really suck. The red had an odd sheen and just didn't look that good when I printed my spool holder for the AXIS.
Here's the results with the red PLA:
I think it is a bit of an improvement. The wing on the top of the F40 broke during my handling of the model, but I've had the same problem with the model using much more expensive Matterhackers Pro PLA so it's probably more the scale that I'm printing the model than the material. The overall look is much nicer in my opinion.
I don't have before and after pics of the black PLA. It changed similarly. It looks a little "cleaner", however my problems with surface adhesion weren't solved.
Overall, I think this project was a success. I wish I wouldn't have wasted so much time fiddling with the Arduino. I'm not an embedded software guy so if you're familiar with that kind of stuff you could probably get this working in a much nicer way. If you decide to attempt something similar I suggest getting the STC-1000 in a 12/24v DC option instead of the 110/220 version that I got. I didn't even realize that it was sold in that configuration till I was reading the manual and saw there was another version.
Thanks for reading!
I got it all kinda working. The code in the github repo does kind of do stuff. The problem is the 4.6ish volts coming off the Arduino pin doesn't trigger the mosfet. The light turns blue to indicate that it should be open, but it isn't. The bed LED doesn't light. If I run 24v from the input across the ground and signal it turns on fine.
I tried to do the work with a relay. Powering the relay circuit from the same thing as the Arduino caused issues I think. It would click on and off but there was feedback in the circuit for reading the temperature causing readings to bounce off. It also seemed to do weird things overall.
I've gotten Arduinos to do little fun instructable projects or "Maker Box" kind of kit. Not so good at building my own stuff. Also, my C++ days are long behind me so the code sucks as well.
If anyone else wants to pick this up I'll be glad to share my knowledge and we can see if we can get something to work. Other than that I'm boxing all of it up!
UPDATE: I've gotten some code together. https://github.com/mikejr83/arduino-filament-drier-box
The current state is that the Arduino writes information to the display, the status and current temperature. I'm working on interfacing with the encoder a bit better. I have it move a "Set Temp" up and down but it doesn't seem to be working correctly.
Once I can get the encoder updating the set temperature correctly I'll be ready to interface with the mosfet control board.
I can say that the whole AXIS project does hate me. I thought that the little power converter that was for the PI could be used to power the Arduino. The Arduino runs on USB power, 5v, right? So I plugged it up as I have in the below picture. Yep, got smoke from the USB port on the Arduino. It looks Ok for now, but we'll see if I can still flash to it over USB. Now I'm glad I didn't plug a Pi into that thing!
I live in swampy FL, USA. The relative humidity where the printer is located has been measured between 60-80%. Some of the silica beads fell on the floor and were green within an hour!
The dry box should be good at the moment. That was a v1 project. The next goal is to have a box to remove moisture from filament, a drier. This will require more heat. That's where I'm working on building the second box with the heated bed so that the box can be brought up to 50-60C.
At the moment it doesn't seem to be too difficult. Over lunch and a meeting I was able to figure out the pins on the EXP1 and EXP2 ports enough to be able to write text to the display and use the rotary encoder.
I ordered some resisters. I plan on using a 4.7k for the pull-down so that the code will closely mirror what is in Marlin.
I'm now finding out that the C++ in Arduino is not like normal C++. Not like I'm a C++ dev either! Any help would be much appreciated!
I have no experience with this but I thought that putting enough silica gel in such a sealed box would be enough to keep it dry. If you have indicating orange silica gel, you should also re-new the silica gel or re-activating it by heating up the silica.