Hi,

I've already upgraded the Z axis and the X axis of my printer with linear rails. They work nicely. Now the last part that needs upgrading (which still uses end-supported 8 mm rods) is the Y axis, which carries the printing plate and moves in a single axis (the Y axis of course).

Now, I have 2 options. I can go for linear rails (probably 12 mm) or for fully supported 12 mm rods (which are supported for the entire length and not just the ends). I have seen some update videos for various 3D printers and in some cases, because the construction is not perfectly alignerd or the other structural parts are not cut to submilimetric precision, the upgrade worsens the print quality, as the tolerance granted by using end-supported rods can sometimes compensate for these flaws. Considering this fact/experience, I can't decide on what to do? Is using fully supported rods a better solution for preventing flexing but also giving some more room for slight mis-alignements compared to linear rails? Or should I go and try the rails as it is the most structurally straight and solid option?

Thanks...

Depends what you have to bolt things to, rails is the answer, rods have much larger bearing blocks, though you can slim them down a little by printing housings(introducing any errors), the heavier it is the more chance of issues. I have one 12mm setup without support, pretty easy to make, I have supported 16mm on my mill setup, but all other printers are using linear rails, some using just one rail which I prefer, ok it's a big expensive rail but probably only the same price as 2 normal rails, and probably could be done with a smaller single rail, I think I've seen a few just using 1 rail.