Hi all,
I just had a look on the website
www.zenbotcnc.com....
The Zenbot mill is made from
plastic material and furthermore is
belt-driven. So, there is
no threaded rod (screw) at all at the axis' drives.
Under all circumstances, most tooth-belts have remarkable backlash, depending on material and pulley geometry used.
(of course, there are "low-backlash" belts, but even the pictures on the zenbot website show a very small belt, which cannot be low-backlash.)
In other words: For this type of machine (and price...) the reported tolerance seems to be normal
On the other hand, it seems to be a very good deal for beginners to get familiar with CNC-technology as the price is very low.
best regards
Konrad