32-Bit Heart Transplant for the Robo R2

I had the same thought... a 32bit BTT Octopus, Raspberry pi and Klipper firmware... Did you ever go anywhere with this project?

 

I am currently running an Octopus with Klipper. But my printer is pretty heavily modified at this point, it still vaguely looks like an R2, but the chassis is about the only thing left that is stock. It is definitely the 3D Printer of Theseus at this point.

That said, once you move to a 3rd party mainboard and klipper, it's actually pretty easy to set up. You know what pin every connector on the mainboard goes to, and it's just a matter of defining pins and settings. I've probably gone a bit overboard making my printer behave exactly how I want it to, and my config file is somewhere between 1000-1500 lines (I've actually broken it up in multiple config files using includes to make it more manageable.)

 

Wow, I would love to see an understand your setup

 

This is what my electronics bay currently looks like.

It's a BTT Octopus, a Mean Well 24V 350W, and a Raspberry Pi 4 (under the power supply), with a Waveshare CAN Controller HAT on it.

At this point I am actually using very few of the actual ports on the Octopus. It basically handles the bed heater and thermistor as well as a generic 10k thermistor that I use to monitor temps in the electronics bay. The green board at the top is a custom PCB I designed that uses the GPIO on one of the TFT headers on the octopus to let me use true 4-wire PWM fans. I've got two 60mm blowers (you can see the edge of one of them pointed into the shroud I designed to cool the stepper drivers, the other is under the PS doing air intake duties) and two Noctua 4010s cooling my X/Y steppers. The 4-wire PWM lets me control the fan speed much more reliably as well as monitor fan RPM.

Here is a shot of the top part of my printhead, and this is why I have so few things plugged into the Octopus anymore:

This is a custom PCB that I designed and built that includes an embedded TMC2209 driver for the extruder, as well as its own STM32F103 processor. The MCU here talks to the RPI via CANBUS, so the only wires I have going from the printhead to the electronics bay are a 24V power wire, and 2 wires for the CAN interface. Klipper supports multiple MCUs and can still have solid timing accuracy over high latency interfaces like CAN. I based the design off the Huvud Printer Toolhead board, and except for the stepper driver and the hotend heater control is mostly a breakout. It has 4 4-wire PWM Fan outputs that are selectable between 12V or 24V, a 3-pin connector for use with a bed sensor (I use a Precision Piezo Orion to directly probe the bed with the nozzle, but any 3.3V sensor with a digital discrete would work), and a 2-pin connector for use with a chamber temp thermistor (In the first version of the board I tried to use an integrated thermistor on the PCB itself, but the tmc2209 heats the whole thing up too much and skewed the readings). This is mounted to a custom bracket that lets me use a Bondtech BMG extruder with the stock gantry.


This is the current iteration of the lower portion of my printhead. I am using a Slice Mosquito for my hotend, with the aforementioned Precision Piezo Orion sensor sandwiched between the hotend and the gantry plastics. The Orion is able to detect forces on the hotend with extreme sensitivity (sometimes too much, if I tap the desk too hard while homing it will trigger. I've even seen it try to trigger just from loud noises) and I can get 1-2 micron accuracy on my bed leveling with it. This sensor is also used as my Z endstop. I'm currently using two Delta 4510 PWM blowers with custom fan ducts for part cooling, but I am working on a new design to replace them with dual 5015 PWM blowers and a new 360* duct design (I'm still running CFD sims on that to see if it actually works)

I think that's the majority of the major differences with my printer... Like I said, it vaguely looks like an R2 still, but that's about the extent of it.

 

WOW!!!! thank you for all of this!!!

 

I'm not sure my custom components are mature enough to push out to thingiverse or wherever, but if anyone would like anything here that I mentioned I've got no problem shooting you the stl's and/or STEP files.

If anyone is interested in the toolhead PCB, I'm more than willing to share the design files that you can submit to JLCPCB for build/assembly. I think it cost me something like $80 to have them build 5 PCBs and assemble 2 of them. That doesn't include the STM32, the TMC2209, the two switching regulators, or any of the through hole components. JLCPCB either didn't stock them, or it was considerably cheaper for me to get them myself and solder them on.

 

That's incredible. I would love to try to duplicate the hotend and cooling fan assembly but I am also interested in the custom PCB if I swap out to an Octopus.... Speed is one thing but quality also matters... If I can increase the quality and speed. I will be happy. I just bought a used C2 to play with as well but my R2 is my main workhorse and I have honestly been very pleased with it. I have done PLA, PETG, PC, and even TPU, which all turned out great, I just always am on a quest for more tweaks and improvement.

I have replaced the uptown board with the upgrade from PartsBuilt, added heatsinks to the stepper motors on XY and the extruder. I wired in a fan for the extruder stepper motor thanks to the upgraded board, and I put longer heat sinks on all the drivers.... I think that is about the best I can do without scripting some software and firmware changes, or swapping out hardware.

 

Which PCB, the CAN Toolhead board, or the PWM Fan breakout? Now that I have the CAN Toolhead, the Octopus is extremely overkill (aside from the ability to have 5V/12V/24V Fans) and in my system I could easily revert back to my SKR 2. Either of those boards would work with an SKR 2 or other BTT device (maybe even other mainboards, depending on how common that TFT headers pinout is)

 

Sorry for the delay in my reply but since I just had the heart bed cable fry for the 3rd time and my RR kit is still on back order, I would very much LOVE to duplicate your setup. Partsbuilt is out of replacement controller boards and I just ordered an SKR 1.4, I think it’s time to Klipperize this thing… in all honesty, I’ve been very pleased with the printer… it’s time to show it some love with a proper upgrade thanks so much!

 

Looking for Jerome Helbert though, I want to model my work after his

 

Sorry, I saw the email about the comment the first day, but hadn't had a chance to get back to it.

What exactly are you looking to duplicate, all of it? The one caveat of switching to a 3rd party mainboard is that you can't easily use the stock cable going to the toolhead anymore. Are you planning to replace that as well, if so are you interested in the CAN Toolhead I designed? For my original swap to a new mainboard I ran discrete wires for everything, with connector breaks at the toolhead. This was messy and had reliability issues with the connectors and all the movements...

As I mentioned, I prefer to use PWM (4-wire) fans, and my toolhead PCB will only work with those style fans. A regular 2-wire fan will just 100% all the time if you tried to use one of those.

If it's everything, I'm more than happy to share all my design files and you can produce everything yourself.

 

@Jerome Helbert

I essentially want to copy off of the work you did, but with one exception. I do agree that your octopus is way overkill so I will use an SKR but pretty much identical to everything else you’ve done, maybe not upgrade the mass on the motion control, but we will see. I know I have a brand new SKR 3 EZ, a drawer full of closed loop stepper motors and power supplies and cabling components coming out of my ears and I don’t have classes resuming until the end of November… I’m ready to get cracking on this haha… yeah I said drawer full of closed loop stepper motors… BTT S42C V1.1 to be specific… it’s a long story

 

I switched to klipper about 2 months before my stock mainboard died and I used that default config file to start with. I don't have a copy of what my end R2 klipper config was, but I think just about everything worked out of the box with that one.

Even without the bells and whistles that klipper adds in, I immediately liked it because I could change printer config parameters that would normally require a recompile of Marlin just by editing a text file on the Pi and restarting klipper.

But then you add in things like input shaping (ie resonance compensation) and turns the printer into an entirely different beast. I was constantly fighting with ringing in my prints if I went to fast, but then I setup and tuned the input shaper and it all went away. I could get 30-40 mm/s print quality at 80-100mm/s speeds.

Ultimately switching to klipper is what led me down the endless customization that my printer has turned into. Being able to run the printer faster and harder, or just to be able to tweak a setting and test it out with a simple service restart made it all super easy.