Fully printable Prusa MMU2 Filament Retract Bank (Buffer)

by Karkovski Jun 3, 2019
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Can anyone post a link for the bearings used. I looked at the original files and purchased the recommended 605-zz 5X14X5, but these do not fit onto the bearing retainer post. The bearing opening is too small?

Please take a look at the PDF in the original thing. The retainers do not fit inside the bearings - you fatten both together with a M5 screw.

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So where does this Bearing_Retainer, Spacer-full and Spacer-open go in this build?

Ah I see now. So what size m5 rods using here?

You need them if you stack the buffer the same way as me. It's 2 pcs, around 135 mm each. You can buy 1 m rod and cut it to size - it's probably cheaper than buying them cut to length.

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What size PTFE fitting this use?

Ah some reason I missed it. M6?

Yes, it's PC4-M6.

This looks like a really neat design. It looks really cool as well.

Thank you :) Most of the credit goes to Dave, the original author though :)

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Am I missing something or do the panels with hexagonal holes not come with the files? The panels that I downloaded were solid.

Take a look at the description :)

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Ha! Thanks. Knew I was missing something. Skipped right over that when I read it.

How are the Spacer-Full and Spacer-Open to be used? It seems that they do not fit correctly in anyway that I've tried. Also I see that in this picture you are using PC4-M6 and in the video on Facebook your using PC4-M10 connectors? Is there an updated Base file for this? PC4-M6 doesnt seems to work as smooth as the video with the PC4-M10's. Base PC4-M6 seems to catch every time you try to load on the inner edge. What screw are you using to connect the Base-PC4-M6 to I assume the Bearing_Retainer? 5mm x ??? And I see that in the video you also have this on its side to I can only assume have gravity help with keeping the Filament_guide over the Roller-Remix?

Spacers are intended for the bottom part if you want to stack everything my way.
Facebook video is not mine. TNDave made this for PC4-M10 fittings, while I had PC4-M6 around, so I modified it. As TNDave suggests in his assembly manual, it's profitable to clean the filament channel with the drill - this might help in your case too. I've also uploaded a new version of the base - v3, which has a bigger chamfer in the entrance and also a wider filament channel.
Hardware listing and assembly instructions are included in the original project - that's why I encouraged to visit Dave's thing and download the PDF. It's M5x12 countersunk, but you can use M5x14 or even 16, I think.
I'm also not sure why Dave recorded his video while having the Retract Bank on the side.

Dave did not use PC4-M10, the M10 pass the PTFE tube through the fitting,he use the 4mm thread and M5, which does not pass through the fitting. These are called out in his instructions.

Ah yes, thanks for pointing this out. The difference is this 1 mm of thread diameter between our connectors.

Thanks! I have found the original page from TNDave and located his PDF file explaining everything. Thank you for your help!

Comments deleted.

Do you have a short video you can upload on this buffer box. It would be nice to see the filament being loaded and unloaded by hand. Also to see it doing color changes via some test print to see it in action. Thanks!

TNDave posted a video on Prusa Community Facebook group: https://m.facebook.com/groups/675831176090951?view=permalink&id=924604394546960

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The link you followed may be broken, or the page may have been removed.

You are probably not a member of this group. Try joining from the main page and follow the first link after you're in: https://www.facebook.com/groups/prusacommunity/

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Thanks! Once I was approved to join the group I was able to view it.

I remixed your base plate to better fit pc4-m6 fittings that have a larger collar than what you must have modeled for. Feel free to include it with your files.

Which fittings do you use? Mine seem quite large in the diameter and I've left some slack on the holes for even bigger ones.

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I ordered these https://www.amazon.com/gp/product/B01NANKRTD/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

What I received wasn't quit what was in the picture, the collar, or the part between the threads and the hex part, measures 8.75mm, so I made the holes 9mm.

As the bank is "stacked", Is there a way to reduce the "internal" panels maybe eliminating the "top" panels and just connecting modified "bottom" panels? In that way you can reduce the number of panels from 10 to 6 (5 bottoms and just one top). I will try to modify the "bottom" panel

Interesting concept. All you'd have to really do is making the lower panel thicker, so it can reach the next stacked one. I can upload STEP files of the panels if you'd like to modify them yourself.

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This is my first prototype making the bottom part thicker, please give me your feedback. I am a novice in CAD...

Thinking of it a little more, it's not that straightforward, but totally doable. I might work something out during the weekend, but will also upload STEP files of you'd like to try it yourself.

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Are the two halves of the buffer glued together. I've built 2 of 5 of these and the puzzle piece connection between the two parts of the buffer seems kind of loose.

Maybe you didn't use the provided braces to hold all together?

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The puzzle connector was supposed to add a little stiffness, but proved not needed at all. M3 screws are enough.

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What hardware did you use to attach all 5 banks together?

Found the answer myself, m5 rod, next question, what's the shortest rod I can get away with using?

I can't answer it right now as I'm away from home right now, but if I recall correctly, 5 banks are 125 mm wide, so you need around 10 mm more in total for the nuts, which gives us 135 mm.

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Ordered some 150mm since 130mm isn't available right away, looks like I'll be all good. Thanks!

Keep in mind you need at least 2, preferably 4. I've bought 1 m of threaded rod at a local hardware store and cut to length. I'll also prepare spacers so there's no need for nuts in the lower section.

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Yup, came in a pack of 5. Spacers would be much appreciated

I've added the spacers, enjoy ;)

Thanks, I assume the open spacers are for those who have already assembled their bank?

Kind of ;) you can use either, no matter of it's assembled or not

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