new-spool dry box by tommyvn

Last crawled date: 3 years, 4 months ago

All the other filament dry boxes that I looked at weren't quite scratching my itch, mainly my itch to be cheap, so obviously i had to make one myself.
I wanted one that
is cheap to print
handles spool rewind for my mmu2s
doesn't need me to order loads of other parts (i already had the rollers from the prusa mmu2s trays and the bag from my prusament which is most of the parts)
fits on my desk
has a window so i could see how much filament was left
looks mainly made of actual trash, does rewind really work on this piece of junk?
The reason the ptfe loops around is to offer some slack for rewind. it will tend to expand at the point where the two tubes meet in the bag, pushing the two ptfe parts away from each other to take up the slack rather than unrolling much on the spool itself, which seems to offer just enough slack to avoid tangles. I plan on trying an extra loop around of ptfe to see if that means the spool itself is touched even less than with 1 loop but i'm lazy and it's working, so one for another time.
I've not used it loads yet tho so maybe i've just been lucky but the cool thing about it is it cost me next to nothing to make so i won't be super sad if time teaches me that it really is trash.
If you don't have a mmu2s or something that pushes filament back to the spool you can skip this entire mechanism, keep stuff even more simple, less parts and just have the egress ptfe tube.
BOM
PTFE tubing
5x passthru bowden connectors, the ones that you can push the ptfe tube all the way thru
2x nuts that fit the bowden connectors, fairly sure this is m6
4x 608 bearings (you've already got these if you bought a mmu2s)
2x 8mm diameter, 120mm length roller tube (you've already got these if you bought a mmu2s)
a plastic bag big enough to hold both the holder and the spool and still have some clearance when closed (you probably already got this with your filament, mine is the prusament bag)
Assembly
Print it
attach the bowden couplers to the center holes, opposite sides
attach 2 PTFE tubes as shown in the photos
place your bearings and roller tubes. all ends of ptfe go over the top with the exception of the one that will carry the filament to your printer, this one goes under
put the spool holder in your bag and note the best location for the egress tube, take it out again
I made a tiny incision with a craft knife, like much smaller than the bowden connectors thread, and then i screwed the bolt inside to the bowden connector outside, forcing it thru the plastic. In hindsight the small hole might not even have been necessary, once the thread took it probably made the hole for me. do this
the bowden connectors allow push movement in one direction only, so the next step might be easier if you take the egress tube out, and also if you make sure the egress tube's bowden connector on the holder is oriented the same way as the one on the ziplock bag so you can push it all the way
place the spool holder in the bag and push the egress ptfe thru the bag's bowden connector, thru the center connector, and a bit over the top of where the spool will go
Use
connect the bag to the printer
spool going in the bag...
feed the spool into the ptfe tube that does not egress the bag until it sticks out the other end
easiest if it's sticking out a lot, like far enough to reach your printer almost, start feeding it into the egress tube
by now the spool is all the way in the bag with the filament at your printer, throw in some desiccant and close it up