Every design has it's pros and cons, using two screws has disadvantages, mainly in leveling. You cannot lower or raise your bed by hand without destroying your calibration. They do however increase leverage, but watch the weight and "racking", where it gets knocked out of shape. I was never a fan of that system and after having used it, I was even less enthused.
Linear bearings work well, but you will need to lube the rails, this collects dust. This also something you will need to contend with. V-slot type systems are quieter, smoother running, and no oil/lube to deal with (V-slot uses cartridge bearings and delrin rollers). As a rule though, 3d printers DO NOT like dust. It will clog your nozzle, infest your pulleys, and contaminate your build surface. Despite some people building all-in-one printer/mills, it's not really even a good idea to even be in the same room as mills and cutting equipment.
On your parts, PLA will warp in a car on a hot day., While ABS will not warp in the car, it has severe warping issues once you exceed 4-5 inches in length, even with a heated bed. To go larger, you need a heated chamber. Using PLA for carbon is a good option, and there is also nylon. ABS is the devil.
Again, I HIGHLY recommend building a pre-designed printer first, at the very least a kit. It will save you time, money and a lot of headaches while filling in a lot of the blanks. Pick a design similar to what you ultimately want, this will let you see what is good and bad about the design. Some things on it are similar to CNC mills, but printers also present their own problems, like filament feed, temps, cooling and more. The frame and electronics are the easy part, the linear movement can be an issue, but really, extruders and hot ends are the bane of 3d printer users. They are where almost all your troubleshooting and learning will wind up Having no experience, and building from scratch, you will spend dozens of hours figuring out why it's doing ____. I cannot stress how much it will help you.
Linear bearings work well, but you will need to lube the rails, this collects dust. This also something you will need to contend with. V-slot type systems are quieter, smoother running, and no oil/lube to deal with (V-slot uses cartridge bearings and delrin rollers). As a rule though, 3d printers DO NOT like dust. It will clog your nozzle, infest your pulleys, and contaminate your build surface. Despite some people building all-in-one printer/mills, it's not really even a good idea to even be in the same room as mills and cutting equipment.
On your parts, PLA will warp in a car on a hot day., While ABS will not warp in the car, it has severe warping issues once you exceed 4-5 inches in length, even with a heated bed. To go larger, you need a heated chamber. Using PLA for carbon is a good option, and there is also nylon. ABS is the devil.
Again, I HIGHLY recommend building a pre-designed printer first, at the very least a kit. It will save you time, money and a lot of headaches while filling in a lot of the blanks. Pick a design similar to what you ultimately want, this will let you see what is good and bad about the design. Some things on it are similar to CNC mills, but printers also present their own problems, like filament feed, temps, cooling and more. The frame and electronics are the easy part, the linear movement can be an issue, but really, extruders and hot ends are the bane of 3d printer users. They are where almost all your troubleshooting and learning will wind up Having no experience, and building from scratch, you will spend dozens of hours figuring out why it's doing ____. I cannot stress how much it will help you.