I'm in the midst of building my prusa now that I have all the parts printed. I'm in the USA so metric sizes are tough to get ahold of. I found some precision ground 8mm smooth rod from McMaster-Carr.

Product Number 5544T27 on page: [www.mcmaster.com]

I believe this should work? Thoughts? Plan on using lm8uu bearings which is the main reason to use 8mm instead of 5/16.

take a gander at part number 88625K67

Are you suggesting this because of the price solely? Because that is only a 3' length and the one I mentioned is sold as 6' so the price is almost identical. Not sure if the tolerances are better on that or not without doing a few conversions.

from what i understand it is a higher quality steal that won't vibrate or sag under its own weight as easily but I am no expert. also all the prusa plans I've seen call for 3 3ft rods so if you buy 6ft rods your spending an extra 5bucks not to mention the cost of shipping a 6ft long box

Ahhh, thanks. I figured i'd have an extra 3' laying around for future projects, but if that steel isn't the best then I will definitely going with your suggestion. Thanks!