[A5] Rewindr - Made for Prusa MMU3

Update 18 June - The A5 release 

(actual info about A5 further down)

I want to thank you for your continued interest and support in the Buffer Units. The latest update was originally scheduled for release on June 18, but I'm incorporating some late development changes to the PTFE-guide (basically changing the input hole for the PTFE-guide for easier loading). I decided that it was better to make the unit perfect, rather than releasing a version that is 95% there a bit earlier. 

This product has evolved into something much more substantial than I could have ever imagine. It has created a lot of work that I did not expect from the initial launch of the product.  I was initially hoping for 100 sold Buffer Units this year. But I could never imagine me surpassing that figure within less than a month. It is clear that I have a huge responsibility to make this product better than ever before. That's why I'm really taking the effort of making the A5 version truly great. 

I've also launched my own company, LGB Engineering. It's a company owned and operated by me and it will help me transform the Buffer Unit in to an official product. It's really nothing crazy, I'm not trying to create the next big thing. This step will just make me provide awesome stuff in a more official capacity, (and of course needed for me to properly tax my income).

Goodbye Printables?

No, not at all. But I will stop selling stuff on Printables. This is due to the Stripe payment services provided by Printables making it very difficult for my accounting work. That is why I have instead created a new website powered by Shopify: LGB-Engineering.com. It's not entirely finished yet, but it will be a simple way of buying and accessing purchased 3D-models. Don't worry, if you have purchased the files on Printables you will also gain access to them on lgb-engineering.com! 

The new website will also allow me to create easily accessible resources for each setup, including a more comprehensible assembly instructions layout, part lists and the ability to provide high resolution images. 

Don't worry, I will still be very active on Printables, publishing free 3D-models, setups for the Buffer Unit and communicating with the community. 

Now finally, version A5!

(actual pictures will soon be up!!!)

Version A5 is reworked from the ground up, incorporating tons of exciting features boosting its performance. Here are the main features in a nutshell:

• No spool slip without the risk of spools falling of (new mini-roller at the front)
• Over 50% increased rewind length
• Better rewind strength, eliminating stuck spools.
• Improved PTFE-routing.

Mini-roller

The biggest change is the incorporation of the third, smaller roller at the front of each module. This roller vastly improves the performance of the Buffer Unit. Here is how the mechanism now works:

1. The spools turns the front-roller as usual, slowly raising the Arm-assembly upwards together with the spool.
2. When the spool is almost raised to the maximum height, it starts to touch the new “mini-roller”, turning it.
3. More pressure gets put on the mini-roller when the spool is further raised, and less on the Front-roller. 
4. Finally, there is not enough friction to turn the front-roller and the spool slips on the roller surface, effectively working as a clutch limiting the windup. 

The mini-roller ensures that the spool will slip at the top regardless of difference in spool-to-roller friction. This means that you can run cardboard spools on high friction TPU-sleeves, without the worry of them not properly slipping in the topmost position 

Gears

The gears in the mechanism have been completely reworked, with emphasis on efficiency. With the combination of improved efficiency and a lower gear ratio, the A5 version removes the problem of spools getting stuck in the top position. The higher efficiency partly comes from higher dimensional accuracy, a result of the gear teeth being larger and thus easier to print.

I have also put a lot of time in to the gears allowing for a larger rewind length, balancing rewind strength and rewind length. The new A5 version has a 55% increased rewind length compared to previous versions. 

PTFE-Routing

The PTFE-routing underneath the modules was pretty good before, but not perfect. I wanted to improve the routing in anticipation of the CORE One setup, making it possible to route all PTFE-tubes to the central module. This makes it easier to then route the tubes together straight towards the MMU3. This is especially important for the CORE One, where routing space will be limited on top of the CORE One.

Routing is now easier then ever, where the PTFE-tube can follow smooth channels on the bottom of the Buffer Unit.

Other things!

There will be no 685 and 686 versions of the buffer unit, both bearings will be compatible with the same A5 parts. All bearing pins and holes are double stacked, so any bearing will fit. This of course simplifies things.

The R- and L-Arm are now providing more support all around the back-roller, making the assembly more sturdy. The “lever-rack” (formerly “ring-gear”) is now secured with one of the screws used to attach the R- and L-Arm to each other, making it simpler.

The whole assembly uses 40 less screws than previous versions. There is no longer any need for screws in the bearing pins, making assembly much faster. The new pins are very simple, won't break at all, and are much more reliable. 

The PTFE-guide is much more securely held in place on version A5.

One last thing, I've added connections for a simple spring as an added option to ensure proper rewinding. Its not required, but it can help if you experience extra friction from your bearings. I want to give a huge thanks to @dolphinboy for helping me develop it!

Early access release

I wasn't able to nail the previously stated release date as stated before. I'm already working with some beta-testers who are already getting access to the A5 version, and I will soon further expand this early-access group before officially publishing the files. The official release of the file will have the stamp of approval of a perfectly working version, once that happens. If you are willing to gain access to the A5 early and willing to provide valuable feedback → please contact me.

Thank you guys for your continued patience

- Ludvig (G) Broomé

Development Update

(5 May) Some people are experiencing spools not rewinding in the top position. The next version will adress this, with much higher gear-train efficiency (version A5 will have larger teeth, narrower gears and adjusted backlash, among other improvements!).

Here's a small update on what's going on at the moment. My personal CORE One printer will be arriving soon. This means that I'll soon be able to publish official mounting options for the CORE One. 

I'm currently working on some mayor design changes of the buffer unit to better suite the CORE One. Initially I wanted the rewind length to match that of the MK4, but naturally this won't suffice with the longer PTFE-tube of the CORE One. This will be fixed in the next update. Along with this, the gear-train will be upgraded to be more efficient. I'm also taking the time to upgrade many small aspects of the design, essentially making the design cleaner.

This will naturally be a very large update, so you except the update to be released in 2-3 weeks. I'll be working closely some community members to beta-test this version. If you also want the A5 parts early, please DM me! 

I also want to say that many people are happy with version A4. A new version doesn't mean that the previous one was bad, just that this new one is better. I try to work with the philosophy that if someone experiences a problem, it solely comes down to the design not being good enough and nothing else. That's why I'll continue to work on the buffer unit as long as people share their feedback :)

Update 7 April - Version A4

I've gathered feedback the last couple weeks and concluded that the bearing pins needed an overhaul. Some users experienced extra friction in the mechanism, only to find out that the these pins were damaged. So here it is! Version A4 now has new strong cylindrical pins with slightly bendable parts to hold the bearings in place. I also took the opportunity and updated the Side-panel pins to also be stronger, incorporating the same kind of design. Furthermore, this version includes much higher STL-quality, allowing smoother surfaces for the Rollers. Here's a summary:

• New, stronger bearing pins that won't break
• Stronger Side-panel pins
• Higher quality STL-files ✨ →  smoother Roller-surface

If you have any thoughts on the design or encounter any problems, please reach out to me and I will try to fix it in the next update! 

Update 30 March - Small improvements

I have implemented some things to improve printability. The “bearing-pins” are less likely to break now with stronger connections and bigger hole for the screws. R-Front-roller is also easier to print with adjusted overhangs. 

Update 27 + 28 March - Custom setups and support for COREBOXX

Now you can officially install the BUFFER UNIT inside the COREBOXX. You can find the setup by clicking here!

Many people have also asked if the buffer unit can be used with other printers, enclosures and MMU:s. The answer is yes, and now you can find basic STEP-files for free here to create custom brackets/mounts! They also include PTFE-guides numbered 6-12 for MMU:s with higher filament counts (like the ERCF for example).

Update 23 March - Version A3 

I've been working non stop since the release last week, gathering user input from many of you. Again, thanks so much for the support! This update includes lots of improvements, the main one being the addition of TPU-sleeves for the rollers. This improves friction and makes the rewinding more reliable (special thanks to @BrianAmato_717081 and especially @LucianFlorin_1026103 for suggesting it!). Here’s a rundown of some of the improvement:

• TPU sleeves for all rollers - improves friction with spools, more reliable rewinding.
• New complaint M3 hex nut slots that make inserting nuts way easier. 
• Less pressure on the PTFE-tube from the PTFE-Guide’s locking lever, reducing friction on filament. 
• Added 3MF files for multi-material-parts. 
• Now supports 686 ZZ bearings in addition to the 685 ZZ
• + more small changes

I’m now starting my work on an official Buffer Unit video. I believe I have ironed out most of the common problems some have experienced, but if you have more input please contact me and I’ll make sure to address these in the next update. In addition to the video, I’m now turning my attention to the publishing of the setups for CORE One and COREBOXX.

ⓘ See part compatibility for the new version down below under “printed-parts”.

Update 20 March - Version A2

Thanks to everyone who have purchased the Buffer Unit! I'm working hard to make the Buffer Unit the best it can be. Here are some improvements:

• Small changes for improved printability and assembly.
• Added slot to R- & L-Shell for attaching buffer unit to future CORE One and COREBOXX brackets.
• Improved PTFE-clips and routing.
• Stronger connection between Ring-gear and Arm-assembly. 
• I'm currently working on TPU-sleeves to improve roller friction with spools.

ⓘ Old files are still available. Old Ring-gear, R- & L-Shell, R- & L-Arm and Side-panels are not compatible with the new A2 Version. 

Update 12 March - Version A1

• First release!