BobsCNC E3, Assembly Manual, Page: 63 / 90

Page 63
Carefully insert the lower rods through the Main Frame
and
over the bottom pair of SG20U Bearings, through
each of the X Rail supports until the end of the rod is
seated in the Frame End Mounts.
Step 4
As the SG20U Bearings roll across the rod there
should be a small amount of
preload (i.e., they
should securely engage the rail and roll firmly).
Check the upper bearings to ensure that they are
snug up against the rail. The bearing should move
along the rail when rotated by hand.