Printrbot Play to SKR Mini E3 V1.2 board.

Printrbot Play upgraded to SKR Mini E3 V1.2
Stock Ender 3/5/CR10 display mounted

I have been working on my Printrbot Play 3D Printer updating to a newer 32 bit control board. The Play is at least 5 years old. In fact it is actually older than that, Mine started Life as a Simple Makers Kit (1405). Then it was upgraded to a Play with a kit from Printrbot. It still has the Ceramic UBIS hotend but has a V2 extruder drive. The Printrboard is a F5 and newer than the rest of the printer due to a broken Micro USB port on the original, a common problem with the F5 boards.

So Why upgrade?

The Printrbot Printrboard is nearly impossible to find. They are not being produced by anyone at this time. Printrboards do not have enough firmware storage to take advantage of all the new Marlin 2.0 features. They are a 8bit 16MHz 128Kb Flash. The SKR Mini E3 is an ARM based processor 32bit at 75MHz and 256Kb (512Kb undocumented) Flash. But the real reason to switch? Baby stepping, You can adjust your Z offset on the fly while your print is starting. By using the rotary encoder you can enter “Tune” and turn the Z axis down or up to get that perfect first layer. Then remember to “Store Settings” and it will print well next time. I just installed a new probe. It only took about 2 minutes to get the right offset to have successful prints. If you are an experienced Printrbot operator you know it can be a long and tedious job to get your printer dialed in after a probe, hotend or nozzle cleaning. This alone is reason enough to upgrade. Throw in easy firmware updates, connecters for advanced features like Neopixel and filament runout sensors, many LCD’s supported including TFT’s, it all adds up.

Printrbot Play printers are very solid and robust printers that really deserve an update to newer control boards. They were accurate and reliable printers for their time, but budget 3D printers can out print them due to the age and size limitations of their firmware and control board. Considering the move to a 32 bit board is only $37 plus $8 in JST-XH connectors it should be well worth the effort.

Firmware for this move is not really available as yet, sort of, but is in the works. I am rolling my own build with help from files for a V1.0 board to printrbot . There is a adapter set of boards (adaptrboards) being developed right now to make this switch “plug and play” by a guy named Philip Mally. He is in fact assembling the prototype Beta test “Adaptrboard” release boards as this is being typed. These, with a few additions, should make the swap into a half hour and done deal for most people with no crimping or soldering needed. Firmware is a simple install of a BIN file onto the SD card to install. He has setups for the Play, Simple Metal and the Metal plus (SKR 1.3 board there) being developed. So if you are looking to revive a Printrbot it could be really easy in the not too distant future!

SKR Mini E3 V1.2 Control Board
BTT SKR Mini E3 V1.2 board. The E3 means it was designed as a direct replacement for the Creality Ender 3 3D printer. It has 2209 stepper drivers is Very, Very Quiet in operation. It adds 32bit processor power as well as 256K storage (512K undocumented) This allows all of the latest features rolled into Marlin 2.0 to be available. Plus it has a bootloader for ease of updating the firmware. Add a firmware.bin file to the SD card and turn on the power. About 15 seconds later the board is updated without any special boards or procedures. This makes it perfect for a change. You will understand if you ever went through trying to update a Printrbot board.

The main problem with the upgrade is the connectors. Printrbot used mostly Molex style connectors with some Dupont connectors thrown in. The SKR Mini E3 vV1.2 Board uses JST-XH connectors throughout. It took me about 3 total hours to remove, Strip crimp and install the new connectors. I am sure that those with more experience at this part could get it done in about an hour. TIP; label all of your wires before starting this job. You will save yourself all kinds of heartache if you do.

Finished wiring on SKR board. Wire management still needs to be finished. Notice all of the stepper wires are wired alike! Optocoupler is mounted with 3M double sided Foam tape.
changed to JST-XH. picture has a Creality 1.1.4 board for tests.
Creality 1.1.4 board (the SKR Mini E3 V1.2 is a direct install replacement for this board) and showing the 12V optocoupler to make the induction probe operate correctly.

WARNING: Realize that Printrbot used a short lead induction probe cable, that went into a 3 pin Dupont connector that is different colored wires. You will need to make sure that that you pay attention to this interchange and label the wires under the printer correctly. While you are at it Printrbot, for what ever retarded reason, chose to put uncovered male Dupont connectors to the fan and the induction probe. These pins are powered and exposed if they come unplugged. This will cause a short and destroy your board if it is not corrected. My brother lost a 2 month old printrboard in just this way. So while you are at it, crimp some JST-XH which lock and provide at least a shield for these pins. Not all of the Printrbot’s are this way so make sure yours is not one of these. If it is make sure you correct it!

I used the 12v secondary fan plug (FAN1) to power the probe and the normal Z-STOP plug for signal. Refer to the picture, but it goes like this:

“Connect positive from FAN1 to the brown wire of the probe. Connect negative from FAN1 to the negative INPUT of the optocoupler. From this same negative INPUT of the optocoupler, connect the blue wire from the probe. Connect the black wire of the probe to the positive INPUT of the optocoupler. Lastly, connect the OUT and GND terminals on the optocoupler to the Z-STOP plug on the board.”

Darren J. Green

Optocoupler wiring picture by Darren J. Green.

I found that I had to move the power input from FAN1 to the “Cool Zone Fan” block connector instead.

The next feat is to wire up the induction probe to make it work properly with the new board. To do this a 12V single channel optocoupler board is used. You can also use a voltage divider circuit or diode circuit to accomplish this. The induction probe works best if it is supplied at least 6V. But a direct connection to the board only provides 5V. The sensor can operate from 6V to 36V. But if you put more than 5V, as in 12V to the sensor then the output is also 12V, to the Z stop connector you will damage the board. The Optocoupler allows 12V to power the probe but then switch the 5V that is from that connector to ground when triggered to the board. The board see’s it as a mechanical switch. I saw how to wire this up on a post on Facebook in the Prinrbot Group page by Darren J. Green

Next hurdle is to design an adapter board mount that goes from the printrbot format to the SKR format. Only one screw hole lined up as far as I can see. Also there will need to be a hole cut in the body to allow access to the MicroSD port and the Mini USB B ports. (see later redesign of adapter plate)

This is the board adapter I designed. It turns the board 90 deg. and aligns the SKR MINI E3 V1.2 MicroSD card slot to the MicroSD port in the Printrbot Play chassis.

Another thing to do is design a LCD holder to use the Creality LCD board for controlling the Printer. I will remount the Laptop to the printer and control it from there as I used to, but there are some unique features to using the LCD like setting the nozzle height just by dialing it up or down with the LCD control knob. Instead of having to repeatedly enter G code commands to set the nozzle height, then save through a terminal.

This is it for now so far. The SKR board is delayed until Monday. I will get some more pictures of it and it’s install in the coming days. The induction probe/optocoupler setup needs to be tested to make sure only 5V is output (actually 0V is output, it acts like a mechanical switch in this instance. It switches 5V from the positive pin to the ground pin to signal like a limit switch.) and that it is wired correctly before being plugged in.

Well the SKR Mini E3 V1.2 came in. I drew up several mount adapters to install the board. In the end I rotated the board 90deg. and lined the MicroSD port up with the SD port in the chassis. The USB port is covered but that will be fixed at the next chance with a drill and Dremel with cutting wheel.

MicroSD card lined up with chassis. This allowed the use of the stock Ender 3 display.

After I got the board installed I installed a firmware from Phillip Mally. It immediately showed a “TMC connection error” on the LCD display. But all the steppers were working and it was able to home, including the Z Probe. The Extruder motor was running backwards but that was fixed by swapping the wires in the connector. All of the stepper connectors are wired the same. Left to Right; Red, Green, Yellow Blue, when looking at the board.

Lots of thanks to Philip Mally and Darren J. Green on Facebook. Their posts and help made this easier and turned me back from some dead ends. Phillip Mally’s Adaptrboard set will make this project possible for others to resurrect those old, solidly built, Printrbots with modern control boards.

The extruder is still reversed in this photo. The parts cooling fan wires were moved from the block connector to FAN1 with a JST-XH connector installed. The Probe power was moved from FAN1 to the cool zone fan block as it remains powered. neither of these is correct in this earlier photo. As you can see shortening the wires really cleaned up the wiring mess that was the original Printrbot printers. In some cases more than 20″ of wire was removed.

The TMC Error warning lead me to installing VSCode and the PlatformIO extension to build my own firmware. I finally had to watch a video on how to set up the environment properly. Then lots of time trying to figure out build errors. Many of the settings I copied over from the Play/SKR GitHub config.h and config adv.h had to be messed with until the errors mostly went away. Finally I got a working firmware built and it still had the TMC error.

I reinstalled the original firmware and there was no TMC error, so I knew it had to be settings.

I found that he had set Slave address settings, in the Config.Adv.h that I was following and that was causing the error. Of course it took a whole lot longer than this to figure it out. Once they were all changed to zero the error was gone. I changed a few other things that were nagging me, still need to see why the Y axis uses Y_MAX to home rather than Y_MIN. and it parks at the center rather than at home. I liked the parking at 0,0 better. I will look into this later as a personal preference.

No TMC error message.
Yep, it was printing even with the error, but other hardware problems never let a print finish.

So after I fixed the error I then had to track down some hardware problems that were causing failed prints. After screwing with the cables the cabling was catching on the bed. And the pulley on the X axis was not centered and had to be loosened and re-centered. I am still hearing some noise from the X rods and bearing, they need to be removed and have a good cleaning. My parts cooling fan was plugged together backwards at the upper end and was not working. And the dreaded “banding” is still there. I need to upgrade to a 4 lead Z screw. A future project.

Butttt,,, It is now printing.
Adding the LCD makes this Printer way easier to use standalone. No special naming conventions (AutoO.g) to get it to print from the SD card. Find the file under Media and tell it to print. This means you can reprint files stored on the printer in the future.

So overall the project is a success. I replaced the heart of the printer with a 32bit upgrade and made it work. It is unbelievably quiet compared to it’s original board. Plus I managed not to let the “magic blue smoke” out of any of the parts. Always a plus in my projects!!!

Next upgrade projects:

4 lead Z screw

Hotend upgrade. I am thinking of going to the CR 10 (12V) hotend, mounted Direct Drive,(same as Ender 3/5 but at 12V) or going to a UBIS 13S. For the CR10 hotend I would have to create a new X axis backing plate to mount a different extruder and the Ender hotend. Price and parts wise it would be worth doing it. Frankly the UBIS 13s is an easier upgrade with the current setup, nearly a direct bolt in except for adding another fan. It is more expensive than the ender unit but could not be added to the Printrbot extruder drive. In the end a 13s will probably end up in it. Still might go with a 13S, but have designed an Adapter to mount a CR10(12V) hotend in the Printrbot extruder. The CR10 hotend is in and the adapter threads had to be resized to fit. This opens up the possibility to go 24V. Just change out the heater cartridge to 24V. This would allow me to mount the Laptop back on the printer and use a LM2596 to power it rather than a separate power supply. I would move to a LED style PSU like a Meanwell and mount it to the side. This would give it a power switch also.

Printrbot adapter to allow an Creality CR10 (12V) hotend to be mounted in the stock extruder.

An upgraded build surface!!!!! tired of the Blue tape regimen. I am thinking of using a cut down magnetic build plate from one of the Enders. A spritz of hairspray and they work real well. (Update: ordered a Ender 3 magnetic Build plate, it will be cut in half) NOTE: Ender # style build surface, magnetic removable is here.

I also want to get the laptop(control center) back to work on this printer. That means opening up the SD card port to expose the Mini USB connector on the board. The SKR board uses a CH340 connection. It came with the right cable and it is short enough that it might just be right for the job. NOTE: see move to 24V in hotend upgrade section.

Not planning to upgrade:

Heated bed. I have always used this printer for primarily PLA, so I really just do not think it makes sense. BUT! this board, SKR Mini E3 V1.2, was designed for a heated bed, if you want to upgrade yours. You will have to go to a 350W PSU to upgrade the bed. I used a 6A, laptop style, Brick to power this printer.

A few other things have been taken care of since the last update. The Inductive probe was switched out and now has a JST-XH connectors. The fan already had the right connector but the wire to it was a Dupont, that is now fixed. The printer is printing better than it was, smoother surfaces. Still waiting on 4 lead screws to show up. They have been ordered for weeks. When they finally arrive that is when a total teardown will begin. Everything cleaned repaired or replaced. The PLA parts will all be replaced with new PLA parts.


Numerous changes to this project since it was last updated. a T8-2 leadscrew was added steps set to 1600 layer heights are in .1mm increments now. I tried adding the textured plastic removeable magnetic bed, as on the Ender series printers. The Induction probe could not reach far enough to work through all of the bed surfaces. I bought a 18mm 8mm detection probe and designed a mount for the play. This worked and now the build surface has been updated. NOI MORE BLUE TAPE!!!

Tonight I pulled a couple of wires and added connectors so I would have a cool Zone fan. My Play upgrade only had a parts cooling fan. Now I can upgrade to a UBIS 13S or the other project I have been working on, The CR10 to Printrbot extruder adapter. That project is nearly ready to mount and test. Probably by this weekend. The adapter is screwed into the heatsink. The nozzle is removed. A piece of PTFE or Capricorn tubing is pushed up into the assembly. it is cut a hair long so the Nozzle will compress it slightly as it is screwed down tight. The adapter clamps into the printrbot extruder. This CR10 hotend cost like $16 from amazon. And if it can get the print quality, that Creality printers are known for, it will be a great inexpensive upgrade. Especially true when upgrading to a UBIS 13S is $50 plus shipping and it will need an adapter to work with my Ceramic UBIS wiring. The quality of prints has slowly gotten better. I expect that will get even better when I get down to tuning the new setup and calibrating it!

Another upgrade was I printed some tall footpads from TPU. These raise the printer about 10mm from stock. I also printed a fan mount to blow down over the stepper drivers and stir the air up under the printer. Nothing fancy. I edited the board adapter plate to include mount hole for the new fan mount.

So a lot still happening on this project. Most of it slowly as I am waiting on parts. Amazon has become a nightmare to get stuff from. I will ad more soon and add some more pictures as well.