I looked build logs, and will look more. First i also planed to use nema 23 425 oz (3 Nm) motors. The first time when i doubted about nema23 was when i took my linear rails. They were very heavy because they are also diy, and made from stainless steel. Second doubt was when i spoke with older guy from work. He also has cnc. He uses 9 Nm motors!!!! I said to myself then... WTF are you doing with 3 Nm motors? I think that gantry will in the end be around 20 to 30 kg. Is that heavy for 3 Nm nema motors? I have SFU 1605 ball screw. I would be happy if nema23 could do wood and some small aluminum things. My budget is weak and there is still a lot of work to do.