7. Spool holder and buffer assembly

Relevant for:

MMU2S

Last updated a year ago

Difficulty

Easy

Steps

Available languages

Step 1 Tools necessary for this chapter

⬢Please prepare tools for this chapter:

⬢2.5mm Allen key for M3 screws

Step 2 Cleaning the spool holder base (optional)

This guide is describing an assembly of a single spool holder. Your package should include 5, simply repeat all the steps again until you finish all spool holders.

⬢Take the black plastic spool holder base and turn it upside down.

⬢Using cloth + detergent or IPA clean all four corners from dust and grease.

⬢Let the surface fully dry and proceed to the next step.

Step 3 Sticking foam pads

⬢For each spool holder base prepare 4 foam pads.

⬢Peel off the yellow protective film completely.

⬢Stick the foam pad on the bottom of the spool holder base and hold it for a while. DON'T use too much force, you might deform the plastic shell.

The foam pads are important to increase contact between the spool holder base and the surface underneath and reduce the spool holder from moving.

Step 4 Assembling the spool shafts

⬢Let's assemble the shafts holding the spools, you will need:

⬢Bearings (4x)

⬢Shaft (2x)

Shafts can be black or silver, the dimensions are the same.

Step 5 Assembling the spool shafts

⬢Align the bearing with the end of the shaft.

⬢Assemble bearings on both sides of the shaft.

The rubber seals next to the bearing were used for the purpose of the photography, no need to use them.

Step 6 Assembling the spool holder (part 1)

⬢For the following steps, please prepare:

⬢spool holder base (1x)

⬢shaft with bearings (2x)

⬢mmu2-s-holder-endstop (4x)

Step 7 Assembling the spool holder (part 2)

⬢Rotate the base with the cutout part towards you.

⬢Insert the shafts into the spool holder base. Make sure all four bearings are seated properly.

⬢Insert the endstops in all four sockets. Push them all the way in, but make sure you won't deform the spool holder base.

⬢Make sure the shafts can rotate freely.

Step 8 Buffer parts preparation

⬢For the following steps, please prepare:

⬢M3x40 screw (10x)

⬢M3x12 screw (10x)

⬢M3n nut (10x)

⬢Buffer plate (6x)

⬢PTFE tube 4x2x150 mm (5x)

The list continues in the next step.

The Buffer plates are protected by a thin protective film on one or both sides, you can remove it now. Be careful during the assembly to avoid scratches.

Step 9 New buffer parts

Open the bag with the plastic parts and look for the hooks. There are two versions:

⬢New version with a longer hook compatible with MK3S/+ and MK2.5S. Please jump to the Step 10

⬢Old version with a shorter hook compatible only with MK3S/+. Please jump to the Step 15

All printable parts are also available at prusa3d.com/prusa-i3-printable-parts

Step 10 Buffer parts preparation (new version)

⬢s-buffer-printer (1x)

⬢s-buffer-spools (1x)

⬢s-buffer-spacer (4x)

⬢s-buffer-hook-uni (2x)

As the names suggest, there are parts, which will connect to the printer or to the spools.

IMPORTANT: the holes for the PTFE tubes have to match between both parts. See the picture. Make sure you won't flip them.

⬢On one side you have 3 holes, same goes for the second printed part.

⬢Other side has only 2 holes.

Step 11 Buffer assembly - printer part (new version)

⬢Take the larger printed part (s-buffer-printer) and place it like in the picture with two holes facing to the right.

Prepare something slightly heavy and tall (e.g. empty glass), we will use it in a second.

⬢Grab one plate and slide it in, it will fit in the slot.

⬢Make sure the inner surface has the protective film removed.

⬢The entire assembly will have a tendency to fall over, use the prepared object to support it from behind.

⬢Slide another 5 plates in the printed part. Make sure the surfaces with previously removed protective films are facing towards you.

⬢Use two M3x40 screws and push them through the printed part. Ensure the screws are all the way through.

Don't turn the Buffer over on its side yet.

Step 12 Buffer assembly - spools part (new version)

⬢Arrange the plates on top of the Buffer and slide in the second printed part (s-buffer-spools).

⬢Make sure the side with two holes is on the right.

⬢Seat the printed part on the other side as well.

⬢Secure the printed part using two screws M3x40.

Don't turn the Buffer over on its side yet.

Step 13 WARNING: tightening the parts (new version)

⬢Now turn the Buffer and place four nuts on the screws. Before you start tightening, please read the following instructions:

⬢DON'T TIGHTEN the screws too firmly. You will deform the plates and the Buffer might not work properly. Make sure the plates are parallel and not bent.

⬢It is enough just to catch the nut (use its entire internal thread).

Use this approach on all parts, which are holding the plates.

Step 14 Adding the spacers and hooks (new version)

⬢Turn the Buffer back, two holes are facing to the right again.

⬢Take three s-buffer-spacer parts and place them on the side with two holes.

⬢Secure each s-buffer-spacer with a M3x40 screw.

⬢Take two s-buffer-hook-uni parts and place them on the other side. This position of hooks is compatible both with MK3S and MK2.5S, but you can rearrange it.

⬢Take the last s-buffer-spacer and place it to the corner.

⬢Secure each printer part with a M3x40 screw.

⬢Use six M3n nuts from the other side and tighten the screws. Keep in mind the proper tightening. Avoid deforming the plates!

⬢Now, skip to the Step 20.

Step 15 Buffer parts preparation (old version)

⬢s-buffer-spacer (3x)

⬢s-buffer-spacer-hook (3x)

⬢s-buffer-printer (1x)

⬢s-buffer-spools (1x)

As the names suggest, there are parts, which will connect to the printer or to the spools.

IMPORTANT: the holes for the PTFE tubes have to match between both parts. See the picture. Make sure you won't flip them.

⬢On one side you have 3 holes, same goes for the second printed part.

⬢Other side has only 2 holes.

Step 16 Buffer assembly - printer part (old version)

⬢Take the larger printed part (s-buffer-printer) and place it like in the picture with two holes facing to the right.

Prepare something slightly heavy and tall (e.g. empty glass), we will use it in a second.

⬢Grab one plate and slide it in, it will fit in the slot.

⬢Make sure the surface facing towards you have the protective foil removed. If not, remove it.

⬢The entire assembly will have a tendency to fall over, use the prepared object to support it from behind.

⬢Slide another 5 plates in the printed part. Make sure the inner surfaces have the protective foil removed.

⬢Use two M3x40 screws and push them through the printed part. Ensure the screws are all the way through.

Don't turn the Buffer over yet.

Step 17 Buffer assembly - spools part (old version)

⬢Arrange the plates on top of the Buffer and slide in the second printed part (s-buffer-spools).

⬢Make sure the side with two holes is on the right.

⬢Seat the printed part on the other side as well.

⬢Secure the printed part using two screws M3x40.

Don't turn the Buffer over yet.

Step 18 WARNING: tightening the parts (old version)

⬢Now turn the Buffer and place four nuts on the screws. Before you start tightening, please read the following instructions:

⬢DON'T TIGHTEN the screws too firmly. You will deform the plates and the Buffer might not work properly. Make sure the plates are parallel and not bent.

⬢It is enough just to catch the nut (use its entire internal thread).

Use this approach on all parts, which are holding the plates.

Step 19 Adding the spacers on both sides (old version)

⬢Turn the Buffer back, two holes are facing to the right again.

⬢Take three s-buffer-spacer parts and place them on the side with two holes.

⬢Secure each s-buffer-spacer with a M3x40 screw.

⬢Take three s-buffer-spacer-hook parts and place them on the other side.

⬢Secure each s-buffer-spacer-hook with a M3x40 screw.

⬢Use six M3n nuts from the other side and tighten the screws. Keep in mind the proper tightening. Avoid deforming the plates!

Step 20 Adding the PTFE tubes (both versions)

⬢Take the 150mm PTFE tubes and slide them in to the smaller of the two printed parts. Make sure the PTFE tube sticks out on the other side (inside the Buffer) just 2-3 mm, not more.

⬢Secure the PTFE tubes using five M3x12 screws. You can tighten them slightly above the surface.

CHECK EACH PTFE TUBE with a piece of filament to ensure it can move smoothly inside the tube. If not, release the screw a bit.