My Thingiverse experience

Today I thought I’d talk about the Thingiverse environment and the community as I’ve experienced it, so far.  My Thingiverse experience started with sharing my mounting solution for the Prusa MMU2S filament buffer.

Immediate responses

It has been a couple of days and the initial comments and likes have diminished.  I see when someone adds the thing to a collection in addition to the likes and comments.  I see a count of visits and downloads.

The initial response was exciting.  The likes seem to have slowed down but the downloads are still increasing.  The one comment was a great question and was appreciated.

Thingiverse is a Friendly environment

There is no thumbs down, you can like something or not.  I appreciate getting something for free.  If it doesn’t work out as expected I still get ideas from  examining it or printing it and finding out first hand why it won’t work.

Sharing is fun

I hope to walk into another maker’s space and see reels of filament hanging on a wall above an MMU2s with a version of my mount holding the filament buffer.

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.


Considering a Silicone Heated Pad? Do it!

heated pad installed

Two days ago I  dealt with heat bed failures  where I talked about ordering a silicone heated pad.  It arrived yesterday and today I am up and running.  It is absolutely great!

heated pad installed
Silicone heated pad installed

What a Difference

One of the most annoying aspects of starting a print job is waiting for the heated bed to make it to temperature.  With the silicone heated pad the bed reaches 85 C before the hot end is up to temperature (240 C).

The Silicone Heated Pad

The FLSun Cube does in fact uses the same heated bed size as the  Creality 10 so this silicone pad was a perfect fit. I removed the wires and sucked off the solder from the original bed and then cleaned the back surface with rubbing alcohol before applying the pad.  The hardest part was removing the solder.

The Wiring

The silicone pad has very long electrical leads of a flexible 10 or 12 G wire.  I simply added cable wrap and a male plug.  The Solid State Relay (SSR) is the on/off switch for the silicone heated pad. The pad will remain off until the signal line is pulled high to turn it on.

Solid State Relay for Silicone Heated Pad
Solid State Relay for Silicone Heated Pad

The wire on the silicone pad is very flexible and heavy duty, a lot higher quality than most cords.  This was an unexpected upgrade.

Configuration change

The Thermistor is 100K “3950” (Marlin Type 11).  A thermistor attached to the pad is not as ideal as one embedded in the build plate but I did check it out and it seemed to be within 5 C.  I want to research PID tuning the bed but I will leave that for another day.


My first print is completed and was better than I have ever from that printer.  I feel a lot more comfortable knowing the load from that heated bed is no longer flowing through the control board and whats more I didn’t have to replace the controller.

The Solid State Relay generates no noticeable heat with the heated bed at 85 C.  The wire to the bed remains cool even though the bed is now up to temperature before the nozzle.  I’d say this was a success!


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


Heated Bed Failure

I had a heated bed failure after I cleaned off the PEI sheet.  It was an add-on that I put on but it never worked and was really glued down. I was liberal with the alcohol while I was rubbing it off and I guess that bit of solvent must have changed things with the heating element.  A few hours later my printer had thermal runaway.  The heated bed failed to heat anymore.

The problem was there was no current to the heat bed. The MOFET or something must have blown.  I was planning on changing out the controller and had the replacement on-hand.  Despite having an external MOSFET laying around I wired the replacement controller up running the heated bed through it and and after a few hours experienced the same thing.  I knew I should have used the external MOSFET!


Losing two boards because their heated bed failed in the same way motivated me to research options.  First, I don’t need to replace the controller because I figured out how to use a different pin for the heated bed.

I obviously need to replace the heated bed but I couldn’t find the bed for my FLSun Cube anywhere.  From measurements I determined it is the same as the Creality CR10, 310×310 mm.  Furthermore in “Everything about heated beds” Thomas made a comment that totally made sense to me.  Why are we converting 110V to 12V and then trying to pump 5 or 6 Amps through the control board to the heat bed?  It would be  more efficient to run 110V to the heated bed and pumping 5 Amps at 110 V produces serious heat and there is a silicone heated pad made for the Creality CR10.  I believe it even has holes in the right places and should work with my FLSun.


In my case my the Rumba Plus controller board has a problem with the heated bed circuit.  Using Marlin I changed the heat bed pin to one that is exposed.  I could see that PWM2, which is PE3 (maps to -> Arduino Digital Pin 5) is available in EXP3 shown in this diagram which can be deciphered to Digital Pin via Arduino Pin mapping.  PWM1 and PWM 2 are used for servos and it is useful to know where they are.

With a pin identified I ordered the 110 V silicone heat pad for the Creality CR10  and happen to have a Solid State Relay that can handle the load.  My experience an SSR with a good heat-sink is not a bad idea so I ordered this one online.

Typically you would just use the Heated Bed Output to the SSR signal but as I said, I am using my controller from the heated bed failure.

The safety ground has to be connected to the metal frame because the heat pad will now be using 110 but that is always a good idea anyway because it is good to have  a shorter path than through the controller to ground for static electrical shocks.


Some mistakes lead to discovery.  In my case experience to avoid a heated bed failure don’t pump the high current for a heated bed through the controller board.  If you blow an external MOSFET or SSR (unlikely) it is a lot less expensive to replace.

I have to make note that offloading the heated bed was necessary with my ANet A8 for safety reasons from what I read.  From my heated bed failure experience I believe it is a really good idea.

An  SSR can handle 110V and removes the entire load from the heated bed.  I’ll will print an enclosure to assure it isn’t possible to touch the leads or get burned by the heat-sink and I’ll cool it with a fan.   This posting was about how I use my ‘Project’ printer.  It is the place where I blow up control boards trying out new ideas and learning about 3D-Printing.

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!


Multiple Printers and OctoPrint

OctoPrint (or Octopi) plays a major role in my printing.  Printing from SD Card and especially Micro-SD Card (the Ender 3) where it is easy to miss-insert makes operating from OctoPrint a no-brainer.  But one Raspberry Pi for each printer doesn’t make sense.  Multiple Printers can run on the same RPi but not Out-of-the-Box (OOB).

Multiple Printer Setup

The first step in running multiple printers on the same RPi is to be able to easily identify which printer is plugged in.  Linux assigns names to the USB ports and you must modify the configuration to provide ‘friendly’ names.

Start by plugging more than one printer into the RPi and identify the /dev/tty* for each printer.  From OctoPrint you should see those names in the list and be able to select which one you wish to connect with.

Simply plug-in and run either printer.  So how do you run more than one printer at a time?  The short answer is, you don’t with just a single instance of OctoPrint running.  You need to create additional instances for every printer you wish to run simultaneously.

Let me phrase it a little differently to make it clear.  In this example I will plug in three printers.  With three printers plugged in you can select any of them with the single instance.

Now I’ll jump ahead to having installed and configured everything for two instances of OctoPrint.  Now I can connect with two different URLs to the two different instances.  From either instance I can  select any of the three printers.  This means I can run any two of the three printers simultaneously.

Naming Conventions

With a basic understanding of the environment and how it is structured it is the time to define a clear naming convention.  This will cover:

  • USB Ports
  • OctoPrint URLs
  • [Webcam URLs]

Within these instructions I  was able to get everything working.  I started by identifying the ports via

  • ls -al /dev/tty*


No Printers
No printers attached

SSH into the RPi without any printers plugged in and then plug one printer in and execute it again to see the new port’s name.   In my case it is ttyACM0

One printer ttys list
One printer plugged in

With the port identified I can plug in another printer and see it is ttyACM1.  Now we can scan the attributes and find unique identifiers to define symbolic links.

Printer 1 Attributes
Attributes from Printer

You can can for unique identifiers by running a difference in the captured lists from the two ports.

Attribute Differences

Following the instructions create and edit a 99-usb.rules file where you specify the values from your system.  Based on this example the file is

99-usb.rules creation
Creation of 99-usb.rules
99-usb.rules content
99-usb.rules content


Reboot and verify the ports have symbolic links as expected.

TTY Ports After Reboot
TTY Ports After Reboot

I prefaced the printer identifier with USB so it is possible to identify just the printer ports and using the -al switch on the ls command you can see what ports the symbolic links represent.

From OctoPrint you can select either port.

OctoPrint Serial Ports
OctoPrint Serial Ports

Now it is possible to easily identify the port with a friendly name.

Simultaneous Printing

Multiple Instances

In order to establish a second instance of OctoPrint we must:

  • Copy OctoPrint directory into a second directory I’ll name OctoPrint2
    • cp R /home/pi/.octoprint /home/pi/.octoprint2
  • Copy and modify OctoPrint2 config script
    • sudo cp /etc/default/octoprint /etc/default/octoprint2
    • sudo nano /etc/default/octoprint2

Change the Port and add a basedir to the DAEMON_ARGS

  • Copy and modify OctoPrint2 init script.  Run a find and replace ‘octoprint’ with ‘octoprint2’ except the ‘DAEMON’ which should remain octoprint.

  • Add new OctoPrint2 init script to autostart
  • sudo systemctl daemonreload
  • sudo updaterc.d octoprint2 defaults
  • –> Check the service.  The last statement will start the octoprint2 service on boot but you can check it without rebooting by manually starting the service.
    • sudo /etc/init.d/octoprint2 start
    • systemctl status octoprint2.service


NOTE: The linked instructions provide an example that confused me which is why I made this post, as a augmentation of that document.

The key difference in what I present and what is in the referenced post is:

  1. I reference the two instances using one for the default port, 5000, and the octoprint2 for the additional instance’s port, 5001 which matches my screen shots captured from setting up my second RPi.
  2. I only have one webcam and two RPi OctoPi servers which means one of them does not have a webcam and so the default page was an error page about not having a webcam, so I changed this to one of the instances.

Within the haproxy.cfg file there are sections.  Changes start in the ‘frontend public’ section.  The backend is selected based on the URL ‘path’.   This is how the traffic is routed to the different instances, based on path.  For example, if the original path was http://octopi.local and two printers are defined as described in this document, anet, and mk3 — http://octopi.local/anet/ points at the port 5000 instance and http://octopi.local/mk3/ points at the port 5001 instance.


To assure we can get back to the starting point make a backup copy of the haproxy.cfg file before making changes.

  • sudo cp /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy.old

Within the /etc/haproxy/haproxy.cfg file with sections ‘global’, ‘defaults’, ‘frontend public’, ‘backend octoprint’, and ‘backend webcam’.

Replace the ‘backend octoprint’ with sections to the active instances you created.  A critical difference is the additions of ‘reqadd X-Script-Name:’ to the all the ‘backend’ sections except ‘backend webcam’.

It is interesting to note that the server is octoprint1 and you specify the access by port rather than any reference to octoprint2, which is directory pointed to as part of the octopi instance setup.



Multiple Webcams

Since I only have one camera at the moment I can only refer to the referenced link.


A very long post.  I don’t know that I have all the details perfect but I captured what I could and don’t have another RPi to setup.  This is my notes for when I have need to setup another RPi.


3D Printing or CNC Mill – Getting Started

Last year I purchased my first 3D-Printer kit.  Now I built a MPCNC from parts I ordered online.  This is a guide for getting started in 3D-Printing or CNC milling.


You don’t need a printer or mill to get started!

Don’t get me wrong, having one on-hand and seeing it operate is the best way to gain true understanding but even if you purchase a fully functional 3D-Printer with support you won’t be printing anything original.

The power of a 3D-Printer or CNC Mill comes from the ability to realize what you imagine in physical form. To accomplish this you define and model using Computer Aided Drafting and Computer Aided Manufacturing (CAD CAM) programs.


Luckily there is a free package that will get you started.  It takes some time and effort to learn but provides a visual workbench which I found useful.   FreeCAD works for both CNC and 3D design work with a complete Workbench called PATH for CNC CAM work but I haven’t actually successfully worked through the workflow.  I understand you can use FreeCAD from start to finish for CNC milling.

The scripting in FreeCAD is Python and various support libraries.  By design it is incredibly flexible and powerful but I don’t have enough experience with it to rate it.  I only started looking into it’s scripting capabilities and find myself back in OpenSCAD.


OpenSCAD is my preferred package.  OpenSCAD is a scripting language that manipulate the creation and placements of objects.  FreeCAD introduced me to parts (ie, objects) in a visual way. I found that once I had the basics of Part Design, that is, Cylinders, Cubes, Unions, Differences, Intersections, etc.   OpenSCAD made sense.  Scripts can be parametric and reusable.  Scripting is much more efficient that point, click, drag, setting properties over and over again.


While I’ve seen that FreeCAD offers PATH, and Inkscape has a PATH tool, with my limited experience I’ve found ESTLCam to be the easiest and most complete offering.  For a person with 3D printing experience, these are the equivalent to the  ‘Slicer’ (Cura, Slic3r, etc).

ESTLCam is not free!  That said, it is the only one I looked at that out-of-box (OOB) offers Marlin.   There are so many unknowns for me that was comforting.

While ESTLCam is not free you can use it without paying money.  There is a timer that will waste 30 seconds of your time as a reminder every time you save a CNC file (generate gcode).  This is annoying enough that if you are  using the product you will pay for it.


Maybe you don’t want to be an expert but you need to understand how your printer works to configure Marlin. A typical controller is the Arduino Mega.  Most have a built in Ramps controller board for four to six steppers but the base processor it an Arduino.

FYI: The Arduino community is very open and robust.  If you want to fully understand how a printer or mill does what it does try building a few Arduino projects.  Arduinos are a great introduction to the circuits design that anyone with an interest can pursue.

Ramps boards provide the means to control several steppers.  Stepper motors work with high currents and need special circuits referred to as drivers.

There are many choices for printer controllers, not all of them based on the Arduino (or Ramps 1.4 boards).  I am only going to talk about RepRap boards, specifically the Rumba.


I’ve worked with several boards now and don’t feel it makes a big difference, at least from a programming view.  The main difference is the number of stepper’s supported.  I like the Rumba because it supports six steppers.  This configuration seems to be ideal for everything I’ve done.

A cheaper board may only offer four steppers and have inadequate MOSFETs.  In addition many boards have open slots for the drivers and can work with many of the available drivers.

The point to take away is that the controller board is an Arduino setup to run a printer.  The Rumba, with six motor controllers, makes a good choice for any robotics project.

Rumba for MPCNC

The MPCNC uses Marlin for firmware.  In Marlin you must have at least one extruder.  The MPCNC has two steppers on both the X and Y axis. Because the Rumba has six drivers it is not necessary to run two steppers on the same driver.  In addition the extruder is ready if you ever want to use the MPCNC as a printer. You don’t even have to install a driver for E1, and I’m sure you could tweak Marlin if you really needed to use the E1 driver.

I also used the Rumba on my project printer.  It supported the dual Z motors on the i3 design and I can easily expand to add a second extruder.

On my Cube I have the MKS board which has five drivers.  It also has dual Z so with two extruders it has both Z motors on one driver.  I’ve ordered a MKS Rumba so I can either go with a Diamond (3 head mixing head) or use the spare driver for the Z axis.

My take-away is that I’ve found the Rumba board with six drivers a great all-purpose controller.  It is more capable, cheaper, and versatile and readily available than the Rambo and has become my first choice for an inexpensive controller.


Design is the first step to mastering 3D Printing.  This does not require a 3D-Printer or any additional purchases.  To experience what your printer is capable of you will need to learn CAD.

3D-Printing and CNC Milling use almost identical hardware and firmware.  The basis for all robotics is control of motors through programmatic handling of inputs and outputs.   Surprisingly the simple little Arduino is often the brain.

Finally, a controller for a Printer (or mill)  consists of an Arduino and RAMPS board.  There are many of these available, Rambo, Rumba, MKS and many more but for the most part they are all setup and programmed the same way.

Start with free software unless you already know CAD and have selected a package.  There are many good free and inexpensive choices to get started with.


Got my MPCNC built and I hit a snag.   I’ll blog more on the details  of the build later but since I haven’t posted in a while I wanted to offer a quick update on the blog.


The build went smoothly and everything was going great.   I felt confident that I had a functional unit after a couple of ‘dry’ runs.

My movements were calibrated and I had hacked together a mill job that looked like it was running as expected through the dry runs.

Grease it up!

In my ‘dry runs’ I noticed a couple of things.  There was a jerkiness to the motion in some places and I had read that you should use white Lithium grease on the conduit where the rollers run.

Grease on, moving the X-Y  I had the Rumba board plugged into the computer and powered from testing.  As I moved the head around manually to see if I could spot binding and work it in a little I heard the computer bell from dropping the USB port and re-establishing it.  I realized this was from the motor back EMF so I unplugged the USB port.

To work the grease in I moved the head through throughout it’s range including some rapid movements to see if they produced any binding.  Everything looked smooth so I decided to setup for ‘real’ for one last dry run.

Trouble in Paradise

I had a clear warning that I was creating an issue with the manual movement because as I stated, the computer was dinging with the USB port connecting and disconnecting.   I must have popped my power regulator IC because when I went to run another test run and found it was plugged in but not working.

Trouble Shooting

Nothing looked fried and the power supply tested out but there were no lights on.  The 12V rail on the board was even hot but not the 5V.

So I moved the Stand-Alone / USB Power jumper to USB Power and plugged in the USB and the board and display lit up and booted. So it looks like I fried he voltage regulator.  I ordered a new Rumba+ board and got back up and running.

The first foam cut was behind me and  I had even tried cutting plywood. Plywood is too hard and the cuts were ragged but it the MPCNC performed well.  Confident the configuration was adequate I went to move the MPCNC to the garage.   I tipped the unit to get through a door and gravity did the rest.  The head moved very quickly to the downside and  guess what?  There went the replacement Rumba board.

Warning: Rapid movement on a MPCNC produces enough back EMF to blow circuits.

Lesson learned… before moving my MPCNC in the future I will figure out a way to lock the X and Y axes so the head cannot move.

Luckily I had ordered two Rumba+ boards so there was no down time.  Still, two Rumba+ boards is a significant hit. Hopefully it is just the voltage regulators.  I’ll blog about the experience if I am able to repair either board.


It has been a significant task to build my own MPCNC.  V1 Engineering has done a phenomenal job on their web site and I will be sharing my experience to augment their effort and help others  get up and running with their own MPCNC.

The table and milling bed are not part of the kit.  There are suggestions on the website but actually building a functional MPCNC requires some word working skills as well.  I’ve developed some word working experience and equipment over the years but I am far from skilled.  I will discuss my choice and look for comments and links from other MPCNC builders in another posting.

I have found my 3D Printing experience has value, especially in understanding and setting up the hardware.  Then I found that design and workflow are very different.  Different software, different workflow, and different setup.   I will describe the workflow I have developed in another posting.


Print a CNC Mill

Watching a “Tom’s” video I was made aware of the Mostly Printed Parts CNC mill  that is made with 3/4″ electrical conduit.

Printing Parts

This job is 90 plus hours of printing!  The Prusa MK3 is pumping out prints but not all has gone well.  The printer formally known as an ANet A8 was taken out of service due to equipment failure…. so, I fired up the FLSun Cube.

FLSun Cube

The FLSun Cube kit had several problems and their support response was very slow despite appearing to be reasonable.  I’ve had the printer for a couple of months but only recently received replacement parts and finished the build.  I hadn’t printed with it.   To start, there are no information on settings for Slic3r or Cura.  I have some pretty rugged looking prints from figuring out the right settings.  In the end I am using Slic3r that came with my Prusa so I don’t have to work with different slicers for different machines.

In the end I dialed in PETG and PC on the Cube and at least some of the parts printed will be used in this CNC build.

Material Types

Having seemly dialed it in with Polycarbonate  I was having warping issues so I switched to PETG.  With a little Z-Hop on retraction, and what I would consider a large amount of retraction, and tweaking temperature I found PETG printed nicely.  Even without part cooling the stringing wasn’t too bad.  I found finding the right temperature critical to a clean print.  Too low and there are a lot of balls and rips, too hot there is sagging.  When it is too cold the balls and rips are collected on the hot-end and end up catching and stringing on travel movements.

Dialed in the PETG prints are close to the same quality as my Prusa MK3.  With a parts cooling fan it would probably be the same quality.  So being picky paid off.  I made sure the motion was smooth (thus the problem parts) before I fired it up.  Even as a basic stock printer (other than I did replace the fans ) I cannot complain about the prints.  However, bed leveling isn’t auto.  I print 4 loops on a skirt and 6mm of brim.  That way I can level the bed during the skirt and brim based on what I am seeing and don’t end up restarting to change the Z offset. I can only assume the probe readings change with temperature.


In the past I’ve had really good luck with PC and I ordered several spools from China that I decided would be the best choice for this job.  PC is harder, stronger, and more heat resistant than PETG but as I am discovering it can be tricky to work with.  I will try drying the filament and see if that helps.  When I first opened it, it would stick hard but now I have to really have it dialed in to get it to stick.  In the past I was having trouble with a spool of PC until I tested my dryer and then it started sticking again.  Hopefully that is all I am looking.  There is a lot to learn and for now I have two printers running that are teaching me a lot.  Hopefully I can come up with material management techniques that will address this issue with PC as I really like how it prints.


It took a week of printing.  It seems there is more than 90 hours of printing but I did reprint many of the parts.  At least the FLSun Cube is working and producing usable parts.   The MK3 prints are superior but the Cube prints are not bad.

For $135 you can buy the printed parts.  Considering the cost for the filament that is only about $100.  For $100 you can save yourself 100 hours of printing.

OK, I actually wanted to do the printing.  I want the printing experience!  A couple of more reasons to print your own, being able to select colors and materials.  After doing all the printing I have to say the online pre-printed parts kit is a  good deal.

And then for $286 plus shipping you can buy the hardware and electronics kit.    I spent $275 (which included shipping) purchasing the parts piece by piece.  The main difference is that I went with a controller I am familiar with and ended up with enough spare hardware to pretty much build another unit. Still, there isn’t much difference in cost unless I actually build a second one.

Before you follow my lead and start ordering and printing parts consider what the the original author is offering. I know at after 60 hours of printing and was looking at the really big parts still ahead of me I cringed.   He has a great site and you really cannot beat the deal being offered. For most people I’d recommend buying directly from the author. His site offers all the details.