My first Thingiverse Publication

I couldn’t wait for the Filament Buffer to be shipped from Prusa and my effort was rewarded.  Today I published my first Thingiverse item, a wall mount for the Prusa MMU 2S Filament Buffer.

Wall Mounted Filament Buffer
Filament Buffer Wall Mounted

Desk Space

The MMU 2.0 had trays that held filament and had to be 16″ behind the printer.  I couldn’t fit all five trays back there even after turning the printer sideways.

Clean look and feel

With the five filaments hanging sideways against the wall above the filament buffer everything is clean and off the desk.  I simply attached the filament buffer to the wall and slid the printer into a comfortable spot.

Easy Access

I was able to leave a lot of room above the Filament Buffer and the latch is minimal so it is easy to remove the buffer from the wall to deal with any filament issues or to move the printer. The buffer is easily freed from its ledge.

Filament Buffer Latch
Top filament buffer mount is a light ‘latch’.


I like the end results and look forward to seeing it in action.


Multiple Material 2S is here!

Filament Buffer,Multiple Material 2S

I am anxiously awaiting the Multiple Material 2S upgrades promised by Prusa.  During my wait I have printed the MK3S extruder and even ordered and received magnets (which are not needed – more on that later).

The week the plans for the filament buffer were update on GitHub I downloaded and printed them.  Big issue there (more later).


I have almost removed the MMU 2.0 from my MK3 several times.  The only reason it is still in place is that Prusa releases an update that addresses the issues I’ve observed so I would try again.

To their credit things improved and I learned tricks to salvage a print job baby sitting the printer through all of the changes.

What works well

Having my ‘regular’ colors loaded makes it quick and easy to select a filament and print. Checking that a print starts assures the filament worked and the print is well on its way.

What fails

Filament loading where there are two different issues.  ‘Not quite loading’ is the biggest, where the filament makes it past the filament sensor but does not catch in the extruder.    This causes a missing layer (or two).

And there is ‘the hard crunch’ where the filament is jammed into the extruder gears before they engage.  While this rarely causes the print to fail it is a harsh sound and undoubtedly potentially harmful to the equipment.

I calibrate my filaments with the MMU which helps a lot but doesn’t totally eliminate these issues.  The hard crunch is preferable to the missing layers but I had to tighten the bondtech gear on the motor once so I know it is hitting pretty hard. You really don’t want the filament pushing too far either.

Another issue is dealing with the retracted filament.  The spool holders provided don’t work on about 1/2 of my filaments. It introduces a coil in some filament but if the filament is brittle it will often snap when it pulled into a tight coil.   Other filaments just push back through the adapter to the reel and the loops fall over one of the sides of the reel.  The filament then tangles when pulled.

It takes constant attention to assure the filament made it all the way to the extruder gears because it takes immediate action to salvage a print if it doesn’t.  Every filament change you have to worry about broken or tangled filament . My experience with the MMU 2.0 unit is that it is only slightly better than manually changing the filaments.

Multiple Material 2S

With the announcement of the MK3S they made plans to update all MMU 2.0 owners  to the Multiple Material 2S.  This includes the MK3S update if you print your own extruder parts.  This means they are shipping a new filament sensor module along with some screws and nuts.

For MMU 2.0 owners there are two major changes to turn their unit into the Multiple Material 2S (MM2S).  The filament sensor module, which is the same as the MK3S.  This requires updating the extruder, which you would want to do anyway.

The big announcement in my opinion was…. drum roll please….  The filament buffer!

MK3S Extruder vs the MM2S Extruder

After printing the MK3S extruder parts I picked up some magnets and put together the extruder in anticipation of updating the printer.

News flash:  In the R4 extruder for MM2S the steel ball housing is replaced with a solid and the magnets have no purpose.  The MM2S  uses an arm extended from the filament door.  The only specialized part you need is a filament sensor module which you can order online if you don’t want to wait for the update from Prusa or you have a clone.

Filament buffer

I downloaded the Filament Buffer files and ran into a big issue, for me at least. They provided a .DFX file of the buffer-plate but there is a issue with it that none of my software could get past.  I developed a FreeCAD macro to create a buffer-plate that works but there was another ‘big’ issue; the buffer-plate is 230mm x 260mm, which is too big to print with the MK3.

So I fired up the FLSun Cube which has a build volume of 260×260 mm.  Using the FLSun cube is a long story…

Having a ‘working model’ of the filament buffer in hand really helps.  I like the honeycomb barrier for the top layer but didn’t see it as a viable option for the inside layers after threading a filament.

Filament Buffer
My Filament Buffer

I can now figure out an arrangement to get some desk space back.  The buffer works great!

The Race

So now I am waiting.  Prusa promised a shipment someday in the next few months, and China is already offering the sensor for sale.  Since I have a project printer I need an additional sensor so I’ve already ordered  one.  As soon as I have a sensor I will do the update!

April 12 – The clone arrived and I updated to MK3S / MMU 2S successfully!

I’ve even had a jam due to over sized (way out of tolerance) filament and had to tear down the print-head to fix it.  That gave me a chance to evaluate the R4 revision was designed to make hot end maintenance easier.  The R4 design is an improvement but to clear a complete jam like I was dealing with still required a bit of disassembly.  NOTE:  I didn’t check the sensor adjustment after reassembly.  On the tool change it was pumping filament through from the MMU and wouldn’t stop until I applied pressure to push in the lever to signal the filament had loaded successfully.  It left a huge blob of molten filament on the purge block.  I learned to always check the calibration of the sensor  after doing maintenance on the hot end.


I think the world of Joseph Prusa and fully support his efforts.  The MMU 2.0 almost worked so I am really looking forward to seeing how well the Multiple Material 2S performs.  I don’t expect perfection but I do expect to be able to succeed without baby sitting the printer.

Since I now have a fully functional MMU2S I can say with confidence that the update does address the issues I had been dealing with.  Great job Prusa!  I am now sold on Prusa’s MMU 2S solution and feel confident recommending it.

The last remaining issue was all clearing up the printer area.  I could only fit four trays behind the printer and needed a solution that ‘fit’.  Here is my solution!

Wall Mounted Filament Buffer
Filament Buffer Wall Mounted


Original Prusa MK3S

The Prusa MK3 is by far the best 3D printer I have worked with and now they have released the MK3S.  I got to really appreciate my MK3 while waiting for the Multiple-Materials-Unit 2.0 (MMU 2.0) to arrive.  The MMU  is a story on it’s own but it is also very much part of this one.

MK3 In Review

The MK3 print quality is superior to what I get out of any of my other printers.  Since I upgraded to the R3 extruder with the angled fan I’ve been blown away.  Prusa is setting the standards and has a bright future ahead.

MK3 Issues

That isn’t to say the MK3 was perfect.  The biggest issue I had with it was the filament sensor didn’t work on many of my filaments.  I turned it off a because it just caused problems.

The only other complaint I had is that you have to disassemble the E Axis to clear an hot-end clog. Clogs are rare so this is a minor issue but really shouldn’t require major surgery to clear.

MMU 2.0

I see the potential but it has offered me nothing but pain.  Working with it has taught me a lot about 3D-Printing failures.

Where the MMU shines is having filaments already loaded.  It is really nice to just select a filament in the slicer.  The majority of the time the filament loads without issue and this is a real time saver.

MMU 2.0 – Issues

I’ve already covered the real issue with the statement above,  “The majority f the time the filament loads without issue…”  The problem is when it doesn’t detect that it has not loaded a filament properly and prints anyway there is a gap in the layers where it didn’t have filament.  Needless to say, the print is destroyed in that single act.

MK3S / MMUS 2.0

With the release of MK3S the design of the MMU 2.0 design did not change at all.  The MMUS 2.0 kit is the MK3S kit and a ‘filament buffer’.


What is the ‘S’?   Simply put, it is the new R4 extruder parts.  This is a complete redesign of the extruder and x-carriage.  For MMU 2.0 owners the upgrade is free when they act on the email to go through the ordering process.

  • Filament sensor: Completely replaced with a mechanical/optical solution that detects when the filament door moves.
  • Serviceability.  The R4 extruder does not require a complete tear-down to clear a clog.  I would recommend MK3 owners order the kit to have it on-hand for the next clog even if you don’t care about the filament sensor upgrade.

The kit is a new filament sensor module, a couple of permanent magnets, a steel ball and some nuts and bolts.

MMUS 2.0

The MMU itself has remain unchanged so the MMUS upgrade is:

  • MK3S Upgrade
  • Filament buffer

The filament buffer may be a manufactured part because I couldn’t find in in the ‘printable parts’.  It will be a month or so before I see mine and can report for certain.


The MK3S is out and being shipped.  Upgrades are in the works and MMU 2.0 owners get the upgrade for free. Be sure to act on the email they send.

The testing for the MMUS had 92% success over 600,000 filament changes.  The other 8% completed but required user intervention.  That is a lot better than I have experienced.  I am really looking forward to seeing what they have come up with in action.

The only serious issues I’ve identified on the MK3 has been filament detection.  The filament detection issues was amplified 100 fold by the MMU 2.0.  Sensing when the extruder door moves is a great solution.

The other serious issue on the MMU has to do with the filament from retractions. The current solution, coiling, is comical until you watch it snap the filament a couple of times.  The ‘S’ upgrades should make the MMU a lot more reliable as well as making the extruder serviceable.  Sounds like a fantastic update!


Core-XY with Cyclops and Chimera

To date my only experience in 3D printing has been with the Prusa i3 design.  With that in mind I wanted to make my next printer either a Delta or Core-XY.

My interest in 3D printing revolves around multiple materials and I am anxiously waiting for the release of the new MM unit by Prusa, which should be in May.  While I wait on my order I decided to research the ‘competition’.

Core-XY or Delta?

Joseph Prusa is a leader in the industry so I am using his newest offering as the standard to compare others against.  I think the MK3 is a great printer, but the proof is how it compares to others.

I really like the Cube design of the Core-XY because it looks structurally sound.  I also like the idea of both X and Y being handled on the extruder level.

The Delta works works with a different coordinate system, which introduces  a learning curve.  I haven’t seen any compelling arguments in favor of the Deltas so I cannot justify taking on the challenge at this time.

Instead I found a Core-XY Cube offering that gives me a larger build area,  dual extruder (or mixing extruder), and they even threw in a WiFi link. They have already filled the order and I should see the printer on Wednesday, less than a week from when I ordered it from China.  It was the frame I wanted, dual extrusion and a mixing head to try out.   It will be interesting to see if there is any real difference in the i3 and Core-XY prints.

Someday I may get around to working with a Delta but for now I think I have more than enough research lined up.


Now that I have hands-on experience with 3D printing on the MK3 I am trying to zero in the the best printer for my needs.

3D printers are inexpensive as equipment goes so I am enjoying the freedom to seriously research the options. Soon I will have a printer with with a dual extruder and that allows me to get an honest side-by-side comparison with the MM kit Prusa is offering.  As an added bonus I will be able to work with a mixing head as well.   It will be interesting to identify the pros and cons of the different approaches.  



Up and Printing with my new Prusa MK3

After a couple of days printing with the MK3 I’ve had more success than months with my A8.  I’m not complaining because I purchased the A8 to learn about 3D printing and it accomplished that goal well.  I am simply lamenting on how nice it is to just print and not be looking at what upgrades I could print to make my printer better.  I believe the MK3 is a trend-setter and now with a little experience with the printer I am more convinced than ever that Prusa has delivered again.

MK3 – Second Day Impression

Getting used to new equipment is usually a challenge and  I’ve found the MK3 is no different.  It is a lot like working with an infant.  You have to give it what it needs, when it needs it, and it doesn’t know how to communicate well. It is simply clear that it needs something.

For example, it is cool to load and unload filament on the MK3.  That also means always having to use menus, some of which are not always available.  I’ll talk more about those in another post.

Yesterday I discovered that for some filaments, specifically my Crystal Series transparent orange PETG, doesn’t properly register with the filament sensor.  That is to say, it sees it only part of the time.  I must turn off filament sensing to print with this filament.  I suspect this may be a problem with other translucent and clear materials.

Eliminating the filament detection also helped me deal with auto-loading.  I’ve found, at least while I’m getting used to the printer, I like to make sure the filament is through the tube and down to the gear before engaging. I’ve found some filament is harder to get through than others, especially if it is the curvy from being the end of a roll.  Turning off Auto Loading simply means you must push the button to load the filament.   When Auto Loading is active as soon as the filament is detected it will beep and start loading.  Sometimes I had  trouble getting the filament through the tube and down to the gear fast enough and would have to cycle it again.  It is nice to have an option.


I am very pleased with my Original Prusa MK3 printer.  I’ve been printing with PolyCarbonite (PC) and absolutely loving the results.  The bearing races for air-soft 6mm BBs I printed spin and spin.  I printed a fidget-spinner and am seriously impressed with how well it works.

With my A8 I printed parts.  They were rarely of the quality I was looking for and printing was not consistent or easy.  I spent a lot of time tuning, researching, and working on upgrades, and got in only a little printing.

In contrast my almost everything with the MK3 has been stellar.  The build, first printing, tuning, and more.  Moving on to other materials I am getting to know the printer better and truly enjoying the results.  I have absolutely no need to upgrade anything.

I’ll leave upgrades to the MK3 with Prusa.  I have the Multiple Materials kit (MM 2.0) on pre-order which is now scheduled to release in May. It sounds like that is a ‘bolt on’ rather than conversion so I the printer remains the same even with the kit.

The MK3 is a solid machine.  I am impressed with the quality of the equipment, detailed build instructions, and overall operation.  I am very pleased with my new printer.

Prusa MK3 – Pi Zero W (NOT)

With my Prusa MK3 up and running I was ready to install the Pi-Zero W I had prepared. I didn’t want the Zero installed until I was sure the printer was working and it was nice to just follow their instructions, which are great, step-by-step.

Warning Will Robertson…

I should have stopped when the image for the PiZeroW was 404 on the Prusa site, and I almost did.  Then I read in the comments that it was being worked on and was expected in a few days.  I had already setup manually in preparation so I was aware it had been 404 for a couple of weeks that I was aware of it.  Based on the warnings about the Pi Zero and not having a ‘supported’ build I was a little concerned.

Tear it apart?

Ok, not such an easy upgrade. Take off the cover, remove the board, and push the extra long pins I had to order special for this task through, then reassemble.

Not too bad but not something I wanted to do again making it very concerning that the Zero was so inaccessible.

No Communication…

I had already configured the Zero but in place it wasn’t communicating.  I found the setting to enable the rPi port and then found a posting on how to configure the communications port on the Zero as well as configure OctoPrint.  Whew, that did it!

Working, or maybe not?

Everything seemed to be working but my first six hour print job just stopped mid-job, nozzle frozen in the print. I thought the MK3 was supposed to be smart…

In working with small prints to learn about filament changing I noticed stutters and broken print.  I wasn’t sure what to think of it but printing from SD card I had seen nothing but perfect prints so I suspected the Zero.  There as also overall strange behavior where despite only have one filament change command in the code the printer stopped several times to change filaments.

It was when a job just quit while I was watching and I heard the fans startup like they do after a reset.  I’ve observed the same behavior when OctoPrint first connect with the USB.  This made me suspect the Zero reset it’s communication link or something.  The Zero was connected to the communication pin no matter what I did. When trouble shooting something sporadic it is best to remove what you can to eliminate as much as possible from the formula.

Rip it out!

OK, cover off, board out, rPiZero removed, everything put back together and in place.

I liked the idea of a built in WiFi solution for operating the printer and OctoPrint is what I use.  However, the PiZero is a single core unit and seems to be more of an issue than a solution.

Problems I see with the embedded PiZero

  • Not really supported.  Looking at the supported OctoPrint image there was question on the PiZero, especially related to streaming video.
  • No Video.  Since there is no access to the unit it would be difficult to run a video cable even if video was supported.
  • Incorrect shutdown.  Every time the MK3 is powered off the Pi is powered off regardless of what it might be doing at the time.  This is concerning to me especially since files have failed to load after a crash so I’ve witnessed file corruptions.
  • To access the Zero you must partially disassemble the printer.  There is no way to remove it when troubleshooting. Also, it is always on even if you disable the port via settings.  You could ssh into it and shut it down but a complete removal eliminates all potential conflicts.


I am loving my MK3 and have absolutely no idea of what you could do to upgrade it.  I strongly discourage installing a Pi Zero W.

You get a much nicer printer when you pay for an Original Prusa. It is the printer I wanted and the only ‘pre-order’ I’ve ever placed.   I picked up an ANet A8 while I was waiting to gain some experience. In that, the A8 worked out well, I learned a lot about printing and what can go wrong.  If you buy a cheap printer expect to spend your time printing upgrades for your printer.

I’ve found my ANet to be a very needy device, demanding my attention on a regular basis just to keep it running smoothly.  It is a great ‘hobby’ printer for a DIY person.  It requires someone who likes tinkering and isn’t concerned about being productive because of all the time spent doing upgrades.  For me it has worked out well while I have waited and makes me really appreciate what Joseph Prusa is doing.

I am look forward to just printing with my new printer instead of upgrading.  I’ve already started working through filament changing and can see that I will have a lot to talk about in designing for multiple materials.  I am really looking forward to the Multi-Material kit which will automate the filament changes.  Hopefully in May based on the last announcement.