Newbie question about controller options, SKR, Rambo, Octopus, etc

Getting ready to build my LR3 and had a question about the control board. I’ve seen comments that the SKR Pro is on it’s way out and I’m interested in getting something that is as plug-and-play as possible. For reference, I have some CNC experience (proud owner of a Nomad Pro) and have a diode laser and a 3D printer, too. I’m a mechanical engineer kinda on purpose because the computer science side of things always felt like voodoo to me.

Some things I’d like to be able to do are:

  1. Override machine speed during cutting to fine tune things.
  2. Headless operation for the health of my laptop.
  3. Basically the functionality of the controllers that Ryan sells. (Along those lines, would like some pros and cons of SKR vs Rambo in plain English.)

I will purchase my controller from Ryan regardless. Just wanted to know if I should buy an SKR Pro when they’re back in stock or wait to see if there’s a move to the Octopus Pro or something else.

I have all of my parts printed, made xz plates out of aluminum on the Nomad and was able to tile the yz plate into two operations and made them out of 1/2" acrylic. (The Nomad work area is only 8" x 8".) Very excited to get this thing going!

I think work on the Octopus is not done yet, @azab2c did some coding and tried to (did?) get it working.
Rambo are the “old” boards, the recommended one is the SKR Pro. Those can definitely run headless. Since I am using yet another board I can’t tell you details, but wait for the SKR, I’d say.

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To me, there is not a clear winner. There are positives with each choice, and I think you would figure out a process and be happy with either board. I have a Rambo, and I run headless for the same reason you want to run headless. If I bought it today, I’d probably get a SKR Pro. But if an SKR Pro was not going to be available in the near future, I’d wouldn’t wait.

I doubt you will see any quality difference in cutting between the two boards. In theory the SKR Pro is a bit better. It has hardware math support and runs faster meaning it is better at processing arc g-code commands (G2, G3). Most CAD and/or postprocessors will allow you to turn off arc commands and emulate the arc with a series of linear moves, and I doubt you will see any quality differences cutting wood with arcs turned off. And the Rambo is plenty fast enough to process linear moves at CNC routing speeds.

The SKR Pro (running Marlin) has an edge at laser engraving speeds. On the other hand, the firmware GRBL seems to handle speedy laser engraving better than Marlin, and there is a version of GRBL for the Rambo board. With XLoader, it is easy to swap between the two. I don’t know if that version of GRBL supports the LowRider. It does work for the MPCNC.

As for running headless, the touch display sold with the SKR Pro is easier to use when setting up jobs electronically. If squareness is important, I set up my jobs electronically using the electronic endstops. But, for most of my jobs, squareness is not critical, and I set those jobs up manually. For the LowRider, with the dual motors on the Z axis, electronic squaring is more important (I run a Primo). The Rambo display is just as easy for manual jobs.

The TFT display running in touch mode is running its own firmware and sending those commands across serial connections. We have seen a bug or two in the TFT firmware (now fixed), and serial connections using the handshake used by Marlin are suspectable to electrical noise and possibly other issues. But the TFT can also be run in Marlin mode. So, on the TFT, you can run your jobs in Marlin mode and get around any potential bugs and noise issues associated with touch mode.

On the forum, we see fewer hardware failures and fewer problems with the Rambo board. As some who likes to tinker with Arduino boards, I’ve seen my share of blue smoke and dead microprocessors. The Rambo boards survives problems (usually user mistakes), that would instantly kill other boards.

On the Rambo, the stepper-drivers are hardwired, meaning if one goes, you have to replace your board. On the SKR Pro, they are socketed. On the other hand, In the years I’ve been following this forum, I only remember one Rambo board that had (just) a dead driver, and everything else was working.

The TMC 2209 stepper drivers used on the SKR Pro are quieter, but that doesn’t mean anything with a router running.

I think the TFT sold with the SKR Pro will work with the Rambo board. I don’t see why not, and none of the bright people on this forum raised a red flag when I mentioned it before.

The is a hardware weakness with the SKR Pro related to endstops. We saw a flurry of problems at one point, and almost nothing after. I’m thinking it was that weakness combined with some out-of-spec components that resulted in the problem, and current boards are fine.

We have seen a (very) few SKR Pro boards lose their bootloader. An inexpensive hardware board was required to burn a new one, so it is fixable. I’ve never seen a Rambo board that had a bad bootloader.

It is easier to burn new firmware on the SKR Pro. Just drop the firmware on an SD card, and fire up the control board. The Rambo requires a USB cable and a computer.

The SKR Pro has the ability to add a module to allow you to communicate wirelessly, so that might be interesting. There is some setup involved, and, if I remember correctly, the connection is really slow wrt uploading g-code files. You would still want to sneakernet your g-code files.

—> So, the pros and cons are muddled. Buy either one, and I think you will be happy.


Hello @michmax1 !

Completely agree with, and appreciate all the info/context from Robert.

RE1) Am using Marlin, but many people here seem to eventually graduate to OctoPi/Klipper or some other firmware that enables overriding speed and other settings during an active job. Personally haven’t reached that frustration threshold yet, am still learning and relatively new to this stuff. Came from Genmitsu and Candle which had this feature, I miss that still, maybe Marlin has it and I don’t know?
RE2) “for the health of my laptop.” - you’re wanting to keep your laptop away from the dust? Headless is possible with SKR and Octopus, and many other boards. I don’t know about Rambo? Am concerned about dust and noise, since I need to babysit the cuts, am looking at doing some janky enclosure.

SKR Pro and Rambo have been great boards for many folks on this forum. They’re supported and well understood. There’s a bunch of tribal knowledge beyond the official docs that’s captured in this forum. So much, that ChatGPT rehash plagiarism algorithms can, probably answer most questions you have about SKR/Rambo (for a fee without credit to the providers of the underlying knowledge…).

Am happily using an Octopus v1.1, after killing my SKR Pro, completely my fault, ungrounded user error at 3am. Still waiting for my forum profile to show the Board Killer badge.

Used the fail as an opportunity to buy and try an Octopus v1.1, not a Pro, not an EZ. Bought to have more mod options, the ESP3D on ESP32 Module integration was attractive too, I like those. If you don’t like coding, compiling and burning firmware using USB programmer modules, then, consider V1E Shop’s ESP3D on ESP-01S module for the SKR, if you end up with an SKR.

Learnt from others, encountered issues, worked through those and fixed numerous things. Shared a Marlin snapshot compiled for Octopus v1.1 am currently using at GitHub - aaronse/marlin_2.1.1_515


Reading the last post reminded me that in Marlin mode, and I assume in touch mode as well, the feedrate can be scaled. In Marlin mode, turning the knob while on the info screen scales the feedrate. It can also be done by sending a g-code (M220).

Still waiting for my forum profile to show the Board Killer badge



All good knowledge. Thanks! I think I’m leaning toward the SKR Pro. Once I get a bit of experience under my belt, I may upgrade from there if there’s a reason to. I’m doing this as much to learn as anything else. To this point, CNC has been a self-sustaining hobby, but I’d like to get to the point of profitability over the next couple years.

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Thanks for that well explained response - over the past couple of years I often get buried in the jargon. Perhaps I am starting to understand some of it, but mostly I think what you wrote was clear enough to penetrate my thick old scone!

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