Too many control boards, what a problem!


I have built a MPCNC Primo and have been using it for a while: love it! But it turns out that my needs have changed, and I have decided to build another one!

The one I have is just less than 24 x 36 inches and while it cuts just fine for the work I’m doing, I really don’t need something that large (It also doesn’t fit in the storage space I was planning on using). I will reduce the size about 12 inches on the diagonal, mount the control system on the side of the work area, and use this machine mostly for Laser, vinyl cutting, and pen plotting.

I will build a smaller machine (thanks to Steve Gladen for the deal on his Primo parts) with a 20 x 20 inch work area, drop table, and use that for any milling work.

My current machine uses a RAMBo 1.4 for the controller and it has worked fine, but I have purchased a SKR Pro 1.2 that is not yet committed to a project.

So, the question is: If I’m running the current machine for primarily 2D work and the new machine for milling 3D, which controller should be used on which machine?

Thanks for your input.


2D or 3D doesn’t matter. The SKR Pro 1.2 or the Rambo are both going to be good.

Thanks Jeff. I also have one of the Dring laser/pen controller, but I’m planning on using it for a ZenXY next winter.



Let’s see…

I have a Duet Wifi on my Primo. I really love the RepRap Firmware and the Duet Web Control interface, but it’s definitely pricey.

I used to run an MKS Gen L v1.0(Basically a RAMPS stack) on it. I changed out because I’m too stubborn to give up using arc commands, and the poor 2560 CPU sometimes choked on the math, causing pauses in the cuts. If I didn’t do that, it was fine.

I have an SKR Pro 1.2 on my LowRider. It’s probably going to get converted to a Duet as well, but that’s because I’m building another Repeat printer, and need the 6 channel board for it. I already have the Duet board, so this saves me some money, though it would usually be a larger expense to buy the Duet rather than another SKR. The SKR is a good board, too.

I have 2 of the BDring 2209 pen/laser controllers. Well, I gave one away in a ZenXY table. It works beautifully, no problems at all with a very non-technical user. The other one, I use on my CoreXY laser.

As to which board I’d use where…

As I said, the Mega2560 CPU (In the RAMBo board) doesn’t have a lot of extra grunt for math. It’s good for plotting straight paths, but a little weak with curved paths. This doesn’t pose a problem with proper CAM. (Like turning off the G02/G03 arcs in Estlcam)

The SKR Pro has a lot more CPU, and shouldn’t have this problem.

Now as to which will be better where…

2D CAD often has a lot of arcs and curves in it. We like to round the corners and plot things in arcs when using CNC, because we can. You can turn those off in your CAM, and it will re-do those as a bunch of short straight lines. Those can be short enough that you’ll never see them as anything but curves in the finished product, and even if you use the actual arcs, it just offloads the same calculations to your control board. Still, you might want to do that, so for the primarily 2D machine, I might use the SKR Pro.

3D CAD most commonly produces files as .STL meshes. One of the defining characteristics of this is that there are no actual curved surfaces. Meshes have triangulated surfaces of a bunch of flat planes. Therefore when you machine it, you are typically running a series of straight lines. This is something that the RAMBo is perfectly adequate to the task of, and won’t give you any real trouble. Therefore, it would be a good choice for this machine.

The reality is that it won’t actually matter. The differences are subtle enough that with proper setup, you won’t really notice the difference from the user experience. Maybe if you like the touchscreen interface better for one type of work over the other, but that’s going to be whichever you preffer.