Spool Dry Box


I decided to create a spool dry box. I am printing quite a lot and wanted to be able to keep my filament in perfect condition. For this purpose, it is required to keep the filament dry. I looked at many different design, some of them are using boxes and other are self printed. None of the design I found I could get easily the required parts or I was able to print them on my printer,

So I decided to design a new one. It has to be small enough to be printed on a 220×220 mm table. The design shall be simple enough, has a small hydrometer to show the current level of humidity in the box but also the status of the drying Silicat.

Bottom plate with holder

The bottom plate with the holder are screwed together. The concept is to lay the spool on four ball bearing. The spool shall roll easy on the ball bearings to minimize friction. The bottom element is screwed at the bottom of the box.

Front side with the humidity sensor hole.
Back side with the PTFE Pipe fitting.

Because the box is really small, it is not possible to have the top to be fixed with screws, the spool is no longer passing through the top opening. I used magnets to hold the top place in position. Four ball bearings are holding to spool in place, identical to the bottom system. When the box is closed, the spool is fixed and can go nowhere but where it should be.

The top element.

The top element is the same principle as the bottom plate with the four ball bearings. It also offers two compartments to place 10 gr Silicat packet. The small places on the sides are place for 10 mm diameter with 1mm thick magnets. The same magnets are placed in the inside on the box. When the top element is in place, the magnets are holding the top with the box in place.

Printing the parts

The side box

The side box is definetly the largest part. I printed everything with a 0.8 mm nozzle with a layer of 0.4 mm. It still took 10 hours of printing but without any problems. After the print a few problems showed up. The first is the hole for the sensor is too small. I had to rework the hole. The back hole for the fitting was perfect. I just cut a M10 thread and everything is fine.

The box bottom wrapped.

The bottom of the side box wrapped. I did not notice during the print. At the mounting of the bottom plate, I realized that something was wrong. I had to use longer screw to be able to fix the top. At the end, it worked but it is not pretty. On the next version, the bottom plate and the side box shall be printed as one part. This shall solve the problem.

Sensor mounted after some rework.

The sensor is a simple humidity sensor. After installing the sensor, I realize the spool, when full, is colliding with the sensor ! You can only put a full spool when you remove the sensor. On the next version, I will put the sensor at the bottom of the box.

Fitting for the PTFE pipe at the back of the box
The top plate without the middle Silicat holder and the spool holders.

After installing the middle part and the holder, the magnets are fitting perfectly and hold the part in place. Here again the top plate is not perfectly flat. The part did not wrap but I removed the part too soon from the plate, it was still hot and I think it just bend.

For a first version, it is not bad, it works. The filament is coming out of the box and my titan extruder has no problem working with it. The humidity is keeping constant as long as you are not opening the box and even after a week, it is pretty constant.

Difference between outside and inside boy humidity.

I am pretty happy with the first version but I still have some improvement to do, time for version 2.

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