Prusa i3 Mk2s MMU Frame Spool Support (4 Spools) Space Saver by MonkeyTurnip

Last crawled date: 3 years, 1 month ago

Space is a premium for me, so i wanted to create a 4 spool holder that attached to the top of the frame, and also gave a easier way to feed the filament in to the extruder, than trying to feed in into the bottom of the extruder.
I have been testing this for the last couple of months, and with some tweaks (what the files are now) i have something i am happy with. printing at speeds of upto 70mm/s get no noticeable vibrations/rocking, and print quality has been unaffected. I am aware that some clone printer with a plastic frame can experience the frame bending with weight added to it, which affects the print quality. But with the Original Prusa i3 MK2s frame being metal, i haven't noticed it.
i normally print PETG at 20-40mm/s and its rock solid.
inbetween the supports and you can upto 100mm wide spools on the rollers, but if you stagger over the supports you could get wider. but most spools i have, seem to be less than 100mm wide.
the bend in the PTFE tube is higher than the highest point the nozzle can go, so it wont interfere with tall prints.
Parts List:
2 Prusa i3 Mk2s MMU Modified Extruder For Bowden Style Input
3 Spool Frame Supports
4 Filament Guides
16 Bearing housings
4 end Caps
4 250mm long 4mm OD 2mm id PTFE tube
4 M5 x 7mm brass inserts
4 Festo QSM-M5-4 Push-in Fittings
16 Bearings from the Prusa MMU Filament Rollers
2 500mm long 8mm OD 6mm id Carbon Fibre rods
3 160 x 2.6mm Zip Ties (same ones supplied by Prusa)
I used M5 x 7mm brass inserts that i found on Ebay. loads available for not allot of money. i tried to match what Prusa used, by they worked out very expensive in comparison.
I used Festo QSM-M5-4 Push Fittings i purchased from RS Online. These are the same as the ones Prusa inlcuded with the MMU
https://uk.rs-online.com/web/p/pneumatic-straight-threaded-to-tube-adaptors/1216037/
Slightly modified Bearing housing/Wheel, i modified the design from this design https://www.thingiverse.com/thing:1832235. My design has slightly higher sides.
I modified the Prusa Extruder to take a 4mm OD PTFE Tube from the Filament Guide.https://www.thingiverse.com/thing:2822229
The Bearings are from the MMU Spool holders. saves having to buy some.
the Rods are 500mm long 8mm OD 6mm ID Carbon Fibre rods. i bought these because Carbon Fibre is cool. the inside Diameter of the Bearings are 8mm, and because of that are too tight for the 8mm rod. i sanded to rod to be slightly thinner, and to allow the bearings to slide along the length with out friction.
the Holes for the brass insers are 7.2mm diameter, to allow for material expansion, making the hole smaller. i press fit these in cold, but you could use a little heat if you wanted, to make the plastic plyable.
the fillament guides are designed to have a little bit of flex, to allow them to snap over the rods. they can also slide freely, so they can be position where best for the filament roll you have
The Supports have a internal channel to allow the zip ties to tie round the frame. this is a must, as the weight of the filament and the over hang pull the support over. the zip tie is fed in from the back, it comes out the bottom of the front leg, is wrapped around the frame, and goes into the bottom of the rear leg. through the locking part of the zip tie and it comes out of the top of the support, if you pull it tight with pliers, then wrap it round the pliers jaw and twist (as shown in the photos) you will get a couple extra "clicks" and the zip tie will be very tight. this is important to stop any vibrations/rocking/failing of the support.
the end caps are to stop the end bearings falling off, and to highlight the ends of the rods to make them more visible.
When cutting PTFE DO NOT use side cutters, it crushes the tube before cutting and makes it oval, which makes it harder for the filament to push through. Use a sharp craft knife and it stays round.
The Light that is in the photo is this one https://www.thingiverse.com/thing:2791701