Two guide bushings define an alignment condition for the tube passing through them. Bore size alone does not describe that condition. Review the guides, their spacing and the assembled movement together before attributing a tight spot to the tube.
Locate both guides from a common reference
Identify the guide axes and their positions in the installed structure. Two individually acceptable bores can still be misaligned after assembly. Include the support structure and adjustment arrangement where these affect the common path.
Distinguish clearance from alignment
A clearance requirement concerns the local mating sizes. Alignment concerns how the guides relate to each other along the travel. Tube straightness, surface condition and applied side load are further inputs. Keep these questions separate so a proposed correction does not merely enlarge a bore while leaving the underlying assembly condition unexplained.
Check the assembled travel
Define the required movement and the condition in which it is assessed. If a sample binds, record the position, orientation and applied load rather than reporting only “does not slide.” A useful review includes both the tube and the guide assembly. No universal bushing clearance or alignment tolerance is specified here; agree those values for the actual application.
