Cheap Filament Dehydrator with Precise Digital Temperature & Humidity Readout

Turn a $40-50 Rosewill RHFD15001 Food Dehydrator into an accurate Filament Dehydrator with precise digital temperature and humidity readout and control.

I purchased the dehydrator new from the Rosewill store on Ebay a few months ago for about $38 but the price varies. https://www.ebay.com/itm/174138036618

There are many references on the web on how to easily convert this into a filament dehydrator by using snips to cut out the inside portion of the food trays.

However, I found that the manual temperature control thermostat (range from 35C/95F to 70C/158F) was terribly inaccurate which of course is a concern when dehydrating filament -- too low temperature and it will take forever to dehydrate; too high and your risk exceeding the glass temperature.

Indeed, when you take it apart, you can see that the thermostat is a simple bimetal strip with spring tension that increases as you turn the knob clockwise. However, it seems to be measuring the temperature in the chamber below the dehydrator and thus can't possibly be accurately measuring the temperature of the dehydrator portion itself.

And when I tried to measure the temperature (and humidity) using the ubiquitous small round or square LCD monitors, I found that they topped out at 120F.

So, I decided to add a cheap ($6.98) but accurate STC-3028 "Dual LED Temperature Humidity Control Thermostat+Probe" to measure the temperature and humidity while controlling the temperature precisely. https://www.aliexpress.com/item/2251832814172369.html?spm=a2g0o.order_list.0.0.22361802Rea1rb (be sure to get the 120/240v model). Note I only use the humidity portion for readout, not control.

• I mounted the display in the case using the below-3D printed mount so that the monitor mounts flush to the round case.
• I rewired the inside to bypass the manual cheapo thermostat with the STC-3028 digital one.
• I added a thermal fuse in series since I was a bit paranoid in case something goes wrong
• I added a quick disconnect to the sensor so that I could remove it if/as needed.

Total cost to me for all parts was <$50!!!

WARNING: this requires modifying 120/240v wiring which can be dangerous. Errors or malfunctions could burn your house down! PROCEED AT YOUR OWN RISK AND LIABILITY.

See below for details...