Page 182 - CNC Robotics

Chapter 7 / The Gantry and X-axis

Tighten the bolts, ensuring that the beams are square to the uprights
and parallel to the bed of the frame. If you can't do both, then it's
best that the beam be parallel to the bed of the frame. In any case,
the two spanning beams must be parallel to eac h other, aside from
their relationship to the bed or the uprights. Once the spanning
beams are installed, the gantry should move easily along the length
of the rails. Adjust the bearing holders to remove any excess play but
don' t tighten them so much that they will bind. If the feet moved
free ly prior to installing the spanning bea ms, it is possible that the
beams are push ing the uprights too far apart or that once tightened
they may ca use the feet to toe in or toe out. This ca n be corrected
with shims on one side of a spanning beam (see Figure 7,33).

Figure 7.33
Shimming the spanning
beams.

With th e ga ntry built and installed on its gu ide rails, you will want
to ad just the gantry's moveme nt us ing shims and adjust ing the
bea ring holders.
After you have spent a few, pa tien t hours fine-tuning the ga ntry to
enable it to glide along the rails wit h little effort, yo u are rea dy for
Chapter 8, the z- a nd y-axes installation.

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