With Klipper you are offloading the math onto a more capable single board computer and using the microcontroller more like a central hub to relay information and the real-time critical aspects.
In a SBC it is hard to do real-time stuff but there is access to the much faster processor and far more advanced cores and arithmetic logic units. This makes it possible to add more shaping into the input for directions. So each axis can move very quickly near the limits of how fast the physical hardware is capable. The calculations are made to ramp the speed up and down in ways that a little 8/16 bit microcontroller is incapable of achieving. This is also why printers with a 32 bit micro are a little faster as well. The microcontrollers used are like 16-72 MHz but there is no overhead like with an operating system. However, they are also running the PID control algorithms for the bed and hotend. You need both a SBC and a microcontroller unless you get into super niche setups. OS kernel configurations have issues with real-time tasks due to some of the ways kernel space is abstracted in an OS and how the CPU scheduler juggles running process threads and interrupts in the OS and hardware. People do not typically mess with a SBC on this level like adding core isolation with a dedicated thread with the CPU scheduler set to real time. There are other potential factors like core spin up, temperature, and power management that need addressing in the kernel too for RT. This is as far as I understand it, as this is a curiosity I’ve barely scratched the surface of a few times. Hopefully this abstract overview kinda helps. Think of a microcontroller like a simplified computer from the late 1980s. It is about like an original Nintendo Gameboy but all the extras like memory and RAM are built into a single little chip and the architecture is simplified a little bit. Something like a Rπ SBC is about the same class as a 10yo smartphone. It is actually a TV set top box tuner chip with all the set top box stuff ignored and undocumented. Marlin is like Arduino firmware. It is just a project that is well organized and setup with an extensive configuration menu about like configuring the Linux kernel. You are prompted with options and you select what is relevant. This is then compiled in a Makefile and you upload the binary to the microcontroller just like an Arduino. The software is setup to make it easy to add similar hardware and maximize entry points so that you can try novel stuff. Unfortunately, Prusa does not run Marlin like this. They are on their own branch of Marlin that specifically makes it difficult to configure and make changes. It also makes cloning a Prusa impossible in practice because they can make changes that will break compatibility. This is the underlying reason the real hobby hacker community that originated around RepRap and the MKx name moved to projects like Voron. The limitations and changes to Marlin were due to Prusa not wanting to break upgrade compatibility and sticking with the AVR microcontroller all the way up to the MK4. They pushed the micro really hard to do both the printer and multi material stuff along with all the fine tuning. So that is kinda the legacy reason for how things evolved. Personally, I don’t care that my printer is a slow MK3S+. It works well without ever doing a calibration any more and I can print PLA, PETG, TPU, PC, and PA/ABS/ASA with a few caveats. I don’t run my printer 24/7 or even daily, so I am slower than the machine. I got a little Kingroon KP3S to mess around with Klipper and see if I wanted to build a Voron. I decided not to. Running Klipper means you must setup and dial in all the fine tuning details that Prusa is doing for you with the original firmware. You loose the it just works factor. That is totally fine if your priorities align with this methodology. The KP3S is capable of running Klipper on the original board after just adding the Rπ and loading the firmware. That is probably the cheapest half decent way to mess around with a project printer in Klipper. I never use the thing though.
bluewing@lemm.ee 2 weeks ago
Yes, Prusa runs on Marlin which isn’t a bad thing, but so does Bambu printers.
Klipper does a few things for me.
Klipper allows for a lot of customization if you want it. Everything is a text file. And your printer.cfg is easily editable. And is a cheap way to turn your Mk3s/+ into a Mk3.5 for easily under $100US-- depending on what recommended RPi you decide to buy. Accelerometers are dirt cheap. I bought the expensive recommended $20 KUSBA plus a $5 data cable because I didn’t have one. The RPi 4b I already had for years.
It gives the Mk3s a 32bit controller thanks to a Raspberry Pi 4b running the printer now rather than the 8bit RamBo factory board. The RamBo merely relays the moves that klipper tells it to do.
I can now use an inexpensive accelerometer to setup input shaping very easily.
This gives the printer the ability to print faster without a drop in quality. I went from printing 45mm^2^/sec to 80mm^2^/sec and accelerations from 1200mm^2^ to 4000mm^2^.
This particular conversion is easily reversible in about 10 minutes if I should ever decide I don’t like it. It’s merely a matter of re-flashing the firmware to the RamBo. And reinstalling OctoPrint to the RPi.
This does not mean it’s now as fast as my mini. It’s not and never will be. But it’s far better than it was. For example, in this run of parts, when printing the same part, (identical test connector), with the same filament, the print times are within 10 minutes of each other. The only difference being the Mk3s has a .60mm nozzle installed and the Mini has a .40mm Nozzle installed. I run a .40mm nozzle in the Mini because Bambu optimizes it’s printers specifically for that size. And there is no difference in tolerances and quality. The parts are perfectly interchangeable.
If you are interested, this is the git hub I used to klipperize my Mk3s
foleac@discuss.tchncs.de 2 weeks ago
Do you have a source for Bambu using Marlin? It would mean they violated the GPL since their firmware is closed source afaik.
bluewing@lemm.ee 2 weeks ago
If you open Bambu Studio, and click on the edit box to the right of you machine type and look at the first tab under Basic Settings, and in the Advanced section, its says G-Code flavor-- Marlin(legacy). Now, don’t mistake that for the firmware they use.
Gwingollor@lemm.ee 2 weeks ago
Thanks dor the explanation, I never really took the time to check out klipper. Might be interesting to get some IT students in our makerspace by showing this as a possible project.
bluewing@lemm.ee 2 weeks ago
It could be a fun project for the kids. A bit of googling should get you more information on different brands printers too. Plus all the open source projects available to do mods and accessories that can require some basic to moderate programming skills to be learned.
I know how hard it can be to kids to have enough fun to learn about how to use technology. I spent a few years teaching CAD and 3D printing to kids in school. I also tried to get the machine shop up and running again. But the school would not allow it.
Gwingollor@lemm.ee 2 weeks ago
Ah I’m talking about college students, I run a makerspace on our campus. But yeah, would be cool for a younger demographic as well.
morbidcactus@lemmy.ca 2 weeks ago
I bear modded mine at the same time and a few other things, biggest for me was that I liked my macros on my voron and I could share them and the motors are substantially quieter.
I haven’t pushed it acceleration wise, do you have any print profiles for prusaslicer or the like? I definitely have room to work with on mine.
bluewing@lemm.ee 2 weeks ago
Your Bear mod will be a lot different than my stock frame and E3D Revo V6 hotend. The profiles I have been using are based on what I think I can get away with from what I learned about from the input shaping. I think you can get away with a bit more than I can. Particularly if you went from the 8mm linear rods to a set of linear rails. That would be far more rigid and vibration damping along with the heavier frame. Did you go with a high flow extruder too? I’ve been debating on a .40mm Revo ObXidian high flow nozzle lately. But The cost is high even for the Revo eco-system.
morbidcactus@lemmy.ca 2 weeks ago
I kept them with linear rods, rails were more than I wanted to do at the time. I changed over to a dragon HF after liking it on my voron, just to keep common parts. Hey, its good to know at least that I can probably push more, tuning a profile for it is definitely going to be on my list.
The ObXidian nozzles are really nice, I just have a 0.4mm and 0.6mm regular nozzles, I’ve used a bunch of hardened coated nozzles before, seem nicer than those but haven’t tested much.