Monoprice Select Mini Smoothieboard Conversion

Instructions may change as needed.

Step 1: Introduction

This is my first instructable so you'll have to bear with me.

The Monoprice select mini is a great machine but in being a low priced 3D printer is has its drawbacks and in my experience it's been the main board and the user interface. Although the LCD is great the turn dial is very hard to control. I was not only having control issues but was experiencing some odd problems with my mini's main board. The replacement mini mainboard is $69 (January this year) so I wanted something a bit better.

If you have read on the mini you will know it uses and ARM 32 bit processor. Most of the open source 3D printers use the ramps 1.4 which is an 8 bit processor. I felt by going to the ramps setup I would essentially be downgrading the hardware so that's why I decided on the smoothieboard because it uses a 32 bit processor. In searching I found the MKS Sbase 1.3 board that uses smoothieware which is open source firmware specifically designed for the 32 bit processor.

Step 2: Steppers

The connectors for the stepper motors use the JST-XHP which is the standard and are the same ones the mini uses. You can just plug in the wires to the corresponding X, Y, Z and extruder (E0) connectors on the new board. Some of the directions of the steppers will need to be reversed but what's great about smoothieware is the firmware works in conjunction with a text file located on the sd card. The direction of the stepper can be reversed by editing the text file on the SD card so there is no need to re-flash firmware or re-pin the wires. Only two of mine needed to be revered as they were going the wrong direction.

Step 3: End Stops

The smoothieboard uses a three pin connector for the end stop. Signal (S), Ground (G) and Voltage (V) which is labeled directly on the board with a (S, G & V). This is for an optical end stop setup which would use all three wires. The mini uses a two pin mechanical end stop, Signal (S) and Ground (G). Do not connect to the voltage pin as it may burn the board. I made my own pigtail connector wires as you can see in the picture which goes from a two pin to a three pin connector so I could just plug in the mini end stop wires to my pigtail harness and then into the X-, Y- and Z- connectors otherwise known as X min, Y min and Z min. I found a connector kit on ebay for around $8 which had all the connectors and pins and more than I needed for this project. Depending on how you wire them they may or may not be reversed for the firmware on the smoothieboard. Go on the smoothieware web site (http://smoothieware.org/) it shows you the M code on how to test the end stops for correct operation using pronterface. If reversed this can be edited in the config file on the SD card also. All of mine needed to be reversed in the config file.

Step 4: Thermistors and Remaining Connectors

Most of the remaining connectors have to be cut and connected to the proper screw connectors on the smoothieboard with the exception of the bed and hot end thermistors. There are four locations for thermistors, I connected my hotend thermistor wire to the white connector located next to the green screw in connector and my bed connector to the black connector. The locations can be edited in the config file on the SD card. A sample config file can be downloaded from smoothieware.org and you can edit as necessary.

The STL files I used for this project were a side plate for my modified 8mm gantry, which had provisions for a panel mount usb connector as well as microSD card slot, a mount plate for the 3.2 MKS touchscreen and some board and fan spacers.

The hardware I used was M3 x 16mm screws and M3 nuts.

Well that's pretty much it. Your setup and choice of additional hardware may be vastly different from mine and some may choose to use the ethernet port on the board (I use Octoprint) so I didn't upload any of my printed files. If anyone is interested in the 3D files I used I can certainly upload them to thingiverse.

Also wanted to mention Is that this board is capable of a dual extruder and hotend setup. E1 or extruder one is disabled in the config file I used. The smoothieware web site is a great reference for the settings or changes.

Step 5: MKS 3.2 or 2.8 Touchscreen

I wanted to add this section because I've been asked a few times. There is a package to download for the screen itself, this is copied onto an sd card or usb and inserted into the screen sd card slot or usb port. The MKS-config shows my settings I used for the LCD to communicate to the board. My LCD was V2.0.

Step 6: Files

I posted the files I printed for the conversion on Thingiverse. None of these are "perfect" remix or modify as needed.

http://www.thingiverse.com/thing:2317518

Comments

[StevensC1]

How do i configure the mks board to work? Can you send me the files?

[mfink70]

All the settings are done through the config file. Everything is set there, motion steps, motor amperage, etc.

My configuration / text file and hardware Is different than yours so I can send it yes but it more than likely won’t work unless you have the exact same hardware as I do in your mini.

[Reactive Light]

PDF download link is borked.

[anthony_sleck]

First off, great Instructable! I have mine started and was pointed to your Instructable after I mentioned I was doing a Smoothieboard conversion. So I am curious if you wouldn't happen to mind posting your config you used on the board?

[mfink70]

Thanks! Sorry just looked at my e-mail, been working on a da vinci smoothieboard conversion.

Yes I can post it but be aware my values will be different than yours, for example I have a nema 17 with an 8mm lead screw so the value for Z will be different unless you have the same upgrade.

Here's the config file link.

https://1drv.ms/f/s!AuWPO4YrnME2vB4pcHTaH4uoGGqg

[JonathanH168]

Thanks for the writeup! I saw your post about this instructable on the Facebook group and it was great timing because I had just purchased the mks board myself. I was able to get it running, but not without some confusion. If the instructable is "done", that's great and it's helpful. If you want to spend some time improving it, I had some difficulty with these things:

1. Which connectors on the board take which wires. Some are labeled excellently like the stepper motors, while others like the thermisters have time labels that are impossible to see if you don't have a ton of space where you're assembling the printer. Picture of each section of the board to go along with each step with text saying what you plugged in there would have been really helpful to me.
2. Details of how you determined if your motors are inverted or not. I figured out that I could connect with pronterface and use its controls to move the axes 1 or 10 mm using the manual controls, and that told me that 2 of my motors were reversed.
3. How did you mount the board into the case? It wasn't clear to me if you drilled new holes or not. Also, is your side panel 3d printed? You said that everybody would probably have different needs based on their mods, and that is true, but it would have helped me if you gave links to any models you used and photos of exactly how you mounted it. Even if I do something different, it still would be a helpful frame of reference. I still haven't mounted my board yet and I'm not sure I know how to do it yet, FYI.

Thanks again, this definitely helped me to get the printer up and running again!

[mfink70]

Is any instructable ever really done? There is always suggestions or improvements than can be made to it, kind of why I mentioned instructions may change as needed in the title.

Yes I can certainly post the stl files. I used pronterface to determine the direction of the motors and operation of the endstops. I did drill the holes in the bottom and made some spacers which will be included in the files on Thingiverse. Thermistors can be put in any one of the four slots, the placement of them has to be noted in the config file. I only used the first two but you can install them where you want. My side plate was printed, has a 40mm hole for the fan but could only use three screws to mount it. There is a picture attached to the instructable where I plugged in my thermistors even mentioned what slot I plugged them into.

[JonathanH168]

Thanks! That's helpful info!

[mfink70]

The board is labeled for the fan connector, the heater connector is also labeled, there are two locations that can can be used, I used the first location.

[lachycharts]

Did you have any problems with the MKS touchscreen? I can't see to get it to work with my sbase. It powers on and works, however none of the commands actually do anything.

[mfink70]

Initially yes I did. It wouldn't communicate at all. There is a MKS_config text file in the software package for the LCD. Set your options in there, smoothieware, baud rate, I chose 115200, etc. save and you should be good.

My screen was the MKS v2.0. After I set the correct options it worked well for me.

[DIY Hacks and How Tos]

Great first Instructable. Thanks for sharing with the community.

[mfink70]

Thank you. Well I thought I did ok on it. Sometimes it's hard to explain a project when it's done and you're happy it's working.

Definitely willing to share the knowledge, I learned a lot in the process.