Makes printrbot original a bit faster, belt tightener for x-axis - I use it with GT2 aluminium pulley, original should work also

Printrbot Original - I made a belt tightener for x-axis. The printrbot original is again a bit better - also with GT2 Aluminium Pulley.
I use two M3 - 30 screws with stop nuts.

For y-axis I use this : http://www.thingiverse.com/thing:121101