Up to this point we have concentrated on reducing friction which may have been caused by rough machined surfaces rubbing against each other.
(friction; may have been caused; by rough machined surfaces) (rough machined surfaces; rubbing; against each other) (we; have concentrated; on reducing friction; T:Up to; L:this point) Context(we have concentrated,List([17, 37))):(we; have concentrated on reducing; friction which may have been caused by rough machined surfaces)
we have concentrated,List([17, 37))
friction rough machined surfaces we we
may have been caused rubbing have concentrated have concentrated on reducing
by rough machined surfaces
against each other
on reducing friction T:Up to L:this point
friction which may have been caused by rough machined surfaces