filament dry box for big 2.5kg spools

Seems there are not many filament dry/storage boxes for big 2.5kg spools - so I made one.

It's based on an Ikea cake carrier (https://www.ikea.com/de/de/p/krispig-tortentraeger-20336407/), which turned out to fit quite well around 2.5kg spools and also being surprisingly well sealed.

The bottom part of the cake carrier has one flat side and one with grooves, which allowed to make a 3D printed turntable for the spool being inserted into the inner grooves. The outer groove compartment can be used to either directly pour desiccant into or place some bags with desiccant underneath the spool.

For the top cover of the cake carrier I made two parts fitting the round surface of the cover. The outside one takes a standard 4mm PTFE adapter on the front and a gasket ring can be added to the rear side for good sealing. It also has an empty 4mm bore to plug the PTFE tube when not used and keep it sealed. The inner part is the counterpart for mounting and also adds a bracket for a temperature/hygrometer. I prefer the below white (slight less cheap) over the commonly used black rectangular ones, since they go down to 10% rel. hum. and I compared a bunch of them with a decent humidity data logger and they were quite close (other than lots of the black rect. ones).

Printing

All parts can be printed without supports. I made them max 18cm large, so they fit on e.g. a Prusa Mini. You need one of each parts plus the ball bearing shafts 4x.

The center cup of the turntable click-fits into the top turntable part. No glue needed.

The outer PTFE mount has to be printed with the PTFE hole side facing down. No more than 45° overhangs in that orientation.

The inner PTFE mount with the hygrometer bracket should be printed with the small flat surface facing down and the hygrometer bracket facing upwards. Just a small surface on the build plate, so make sure to have proper adhesion (adding a raft might be good).

Assembly

Should be more or less self explanatory from the pictures attached. Use the back part of the PTFE mount on the inside as drill guide to mark the holes (min 3mm, 3.5mm makes mounting easier). Make sure to not mount it too high or the hygrometer can conflict with the top of the spool. Best to use a wood drill for drilling into plastic which have a sharp tip and hence won't “move” when drilling. The diameter of the bigger center hole for the PTFE tube should be around 8mm min. A step drill is good for that.

In case the top handle of the Ikea cake carrier is a bit loose (and hence not properly sealed/airtight), you can add some glue (I used hot glue gun), see picture.

If necessary, you can add two, three, four rounds of not to thick tape (I used electrical isolation tape) around the bottom part of the cake carrier where the top part touches to improve sealing.

Parts Needed

• Ikea “Krispig” 36cm care carrier: https://www.ikea.com/de/de/p/krispig-tortentraeger-20336407/ (might have a different name in other countries…)
• PTFE tube adapters: https://www.amazon.de/gp/product/B07SKX5P9P/
• Washers for PTFE tube adapters: https://www.amazon.de/dp/B01DF2SIFI/ 
• Temperature and Hygrometer: https://www.amazon.de/gp/product/B0BXRDWYG2/
• Gasket rings, rubber, 28mm outer diameter, 24mm inner diameter, 2mm width: https://www.amazon.de/gp/product/B07JG9BF6B/
• Screws M3x16mm, washers and nuts (I used self-locking)
• 4x ball bearings (standard 608ZZ type, 22mm outer, 8mm inner, 7mm thick): https://www.amazon.de/gp/product/B08K936Y1Z/