I already have a Prussa style printer, but want to move up to the stability of extrusion. I really like the OpenBuilds concept and want to make an X/Y table style printer with the crane Z setup kinda like this: I was thinking that if the hot end stayed stationary (only moving in the z axis) it would be more accurate. I could move away from the bowden setup since all that mass wouldn't be moving around. I know that the bed would be moving on 2 axis now and there is a lot of mass moving the aluminum plate / heater / printed object....would this be more / less accurate than having the X axis on the crane portion of the printer? Here is a video of the x/y being built: I searched around a bit and I haven't found any actual builds with this style. Any comments?
I haven't seen a printer set up like this, but that doesn't mean it's not out there. I don't know if keeping the print head stationary and having the build plate move in the X and Y axes would be any more accurate than more traditional solutions. You are still moving a moderate amount of mass around on a belt drive system that can induce artifacts into the print as the belts stretch from rapid changes in direction. The bulk of the improvement in accuracy will be in making the frame rigid, and the moving parts as lightweight as possible. I think you should build it anyway. It's a cool looking design.
I'm getting read to start my first "from scratch" build having done a 3d printer and CNC machine, so I am by no means an expert. When I first starting figuring out what I wanted and why, my first inclination was to go with the XY just as you've described. It looked cool, I understood it and it would be simple to build. After reading hundreds of comments on the posted builds the consensus seems to be toward a stable build plate that moves in the Z, if it moves at all. While there are different reasons (opinions) the one that stuck with me is that as the build plate moves it creates stress on the printed object. As the object gets taller and/or the build faster the stress increases as does the chance of warping and build failure. Even with Kapton or painters tape, glue, hair spray or ABS sludge... warping is painful, too increase the chances of it happening just didn't make sense to me. as to the "crane" arm... the greater the weight at the hotend, the greater the defection and error. is it meaningful? why not just add a support arm on both ends and avoid it?
