Hello, last year I decided I wanted to try to get into 3d printing as a hobby. I started with a Prusa i3 and after a couple months I felt the need to have a larger printer. What I want to print requires a 30cm x 50cm print bed and I felt like I would get the most satisfaction out of making my own printer. I started out thinking I could just scale up a hypercube, but I found out the hard way that it didn't scale up very well. I currently have 2sqft sheet of 1/4 mic6 aluminum for a print bed sitting in a frame measuring 26" x 32" x 50" and am in the process of trial and error in making it all work. The frame is made mostly out of 2020 extrusion, and will be wrapped in wood. I was worried about the strength of the 2020, but it all feels fairly stiff when I bolt on the sides. I had problems with the frame twisting causing the x axis to bind up, but that seems to have been resolved after attaching the wood. I am at a point where I think I need help with my printer as I have spent more on this than I had originally hoped to. My current biggest problem is with the z axis. I had two 1620 ball screws centered on the sides with 10mm rods/linear bearings at each corner. This rocked back and forth too much so I had to scrap it. I do not have any room at the front or back of the print bed for a third ball screw and don't really want to have two on one side as I had a hard enough time finding a belt long enough for the two I have now. I have switched over to having the ball screws at opposing corners with hopes that that will minimize the rocking. It seems like I will have to make the z axis very rigid and with that I am curious if my drive setup for the z axis will be strong enough to move all the weight. I have a single nema 17, 92oz.in stepper with a 16 tooth pulley driving 40 tooth pulleys on the 1620 ball screws. Will that be enough to move what will probably be 20-25lbs without any print? I am also worried about the X/Y setup, I have abandoned the hypercube design and have moved onto mgn12 linear rails. I started to work on designing my own X/Y, but I am concerned that there are odd problems that may come up due to the size. In my initial testing (no belts) I found that PETG flexes too much for my liking and have a roll of carbon fiber PETG. I also have worries about the belt, and how I might keep adequate tension without creating new problems. Are there any decent setups that I could use with my current 2020 extrusion and mgn12 rails? I am getting a little tired of the trial and error stage I seem to be stuck in.
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