RAMPS and CoreXY

I am working on designing a smaller form factor CoreXY printer for higher precision small parts using parts from a printer I've decommissioned. The motion system on the old printer left a lot to be desired in rigidity and durability so I decided to redesign it. The goal is a dual extrusion, 120 mm x 120 mm x 200 mm build platform with an almost or all metal construction.

Since I am using spare parts, I have enough 1.8 nema 17 motors, other parts, and spare electronics (PSU, controller, toothed pulleys, bearings, etc.). The controller board I have is a RAMPS 1.4 with A4988 drivers. The parts are all in great condition so I'd like to reuse them. However, I am wondering if anyone has experience with RAMPS and CoreXY? And if there are any issues with using RAMPS for CoreXY? I know the 32-bit is always better but since I have the board, I am hoping to use it. Lastly, I am hoping to achieve 80-120 mm/s which I don't think will be an issue due to the printer's size.

Erich

We have pretty different corexy printers (I wanted mine big and fast), but I ran into issues with Marlin stuttering at high speed curves. If you are going for precision with dual extruders, I'm guessing your speeds will be lower and you won't run into that issue.

Other than that, ramps/mega/Marlin was working pretty good for me.

Edited 1 time(s). Last edit at 03/06/2017 12:33PM by Pheneeny.

Pheneeny, how high speed are you talking about? I would like it to be capable of high speeds but would only use it every once in a while.

I initially used RAMPS with my Eclips3D and had no problems with it. I don't recall how fast I ran it, but it wasn't very slow. I've since switched to an Azteeg X5 which is definitely quieter and smoother.

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See my blog at [moosteria.blogspot.com].

Through my tests, issue would start to appear at 60mm/s and would be all over the place at 80mm/s. This was mostly on curves though, not on straight lines. I was able to work around it by using slower outer shell, but still not optimal.

I actually just randomly stumbled upon these videos which matched my experience exactly. Watch the second part as well:
youtube

I'm in the process of trying Smoothie to see if that helps fix the problem.

With 8bit controllers you could try to use a very low acceleration, like 500mm/s² to slow down short moves/curves. But that has an influence on nozzle temp too. ( To hot in curves or to cold on straights )

This is really helpful, especially the video. I'm leaning towards upgrading to 32 bit and finding another use for the RAMPS. I'm not confident that it will produce the results I'm looking for out of this machine.