Intro

Over the week I took some time to do something completely random and unplanned. I decided to disassemble my perfectly working MK3S Bear and remove the Einsy Rambo board. I replaced that with the newish BTT SKR v1.4 Turbo 32 bit board running TMC2209 stepper drivers (The standard SKR v1.4 isn’t much different, this one just has a small boost in the processor speed). This was the first time I’ve done a board swap on my printer and the first time in a long time since I’ve messed with vanilla Marlin. Side note, I’m not a Marlin expert or know a lot when it comes to configs so excuse my noob-ness if I got something wrong.

I watched a few videos that were recently put out by Chris Warkocki on how to configure Marlin for the SKR v1.4 board to run on the MK3S. I did some searching of my own as well and compiled my firmware, that was probably the easiest part of this conversion. I then proceeded to study the wiring diagram provided on his Github and figured out where everything was going before attempting to change all of my connectors. I’m sure someone out there will make a breakout board or conversion cables but I figured that re-crimping the wires to 2.54 JST XH wasn’t that difficult and if I ever want to switch back to the Einsy Rambo, I could just change the connectors on the Einsy Rambo board itself (I’ve done this for a few things already like the bed and hotend thermistors). The fans themselves also needed to be swapped out for 24v fans, luckily I had a 5015 blower and 4010 fan on hand. I was also informed that you could use the end stops to plug the 5v fans in, but I’d stick with the 24v fans.

Setting the board up

The board itself needed a few things done before it would work the way I needed it to. The first thing was removing the jumpers on the SKR v1.4 board for where the TMC2209 stepper drivers were going. Only the 3rd jumpers should remain on all of the steppers on the board. Refer to Chris’ Wire Guide PDF that I linked above if you don’t know what I’m talking about. The other thing that needed to be done was one of the pins on the TMC2209 that controlled the extruder needed to be snipped off. According to Chris, the filament runout sensor won’t work if that pin isn’t clipped. The Extruder stepper is the on with E0-CLS labeled under it, I didn’t realize this the first time I was connecting everything.

Re-crimping the wires did take some time, but isn’t too difficult if you’ve crimped wires before. I believe most of the wires are about 26AWG so they’re not too thin or difficult to work with. The 2.54 JST XH connectors I used were from a set I bought a year ago . If you’ve never crimped cables before there are a ton of YouTube videos out there that show you exactly how to do so. You can also opt to just buy pre-crimped cables and solder them if you find that easier to do. You’ll also need to recrimp your power cables and heated bed. These cables use ferrule pins instead of the fork spade wire connectors that are used on the Einsy. Something to note is that on Chris’ diagram he has the Hotend cooling fan show connecting to the FAN1 connector, the fan should actually be connected to the HE1 connector, so you’ll need to crimp those wires with ferrule pins as well.

After getting all my cables in order I tried to run them through the newly printed SKR v1.4 case and came across my first issue: My cables from my power supply were way too short. I took the opportunity to remove a set of cables from the power supply that were no longer needed. Since the SKR v1.4 only needs a single pair of Power In cables compared to the Einsy Rambo which required two sets of Power In and Power Out cables. Something that I had to be mindful of was the fact that one Z axis motor goes into the ZMA port and the other motor goes into the E1M port, that way the steppers will both be independently driven by two stepper drivers (The stepper driver with Z-CLS under it and the one with E1-CLS under it) as opposed to being controlled by just one (Just the Z-CLS), utilizing all 5 stepper drivers. At the moment my cables are way too long and need to be cleaned up, but it’s more a proof of concept than anything else. I just want to get the new system up and running and cable management will come later. Hopefully my picture below gives you a good idea of where cables are suppose to go.