We evaluate the influence of mechanical tolerances on the field quality in
the LHC dipoles. We show that the most relevant effect is due to tolerances
on the coil and on the internal part of the collars. The sensitivities of
the field error multipoles on the mechanical tolerances are worked out usin
g a finite element model of the dipole Cross section. A MonteCarlo method i
s used to simulate the overall effect of both collar and coil tolerances on
field quality. Correlation between random multipoles is worked out, and a
comparison with the target table of the LHC field errors is given.