How do you read a fit like H7/g6?
A fit describes the interplay between a hole and a shaft. In the common hole-basis system the hole is always H (e.g. H7) and you vary the shaft to get clearance, transition or interference. So H7/g6 always gives clearance (running/sliding), H7/k6 a close transition (centring) and H7/s6 a heavy interference fit (shrink fit). The number is the IT tolerance grade: lower = more precise.
Frequently asked questions
Which fit for a rotating shaft?
H7/g6 (light clearance) or H7/f7 (more running clearance with lubrication) are common for rotating shafts and bushings.
What do the letter and number mean?
The letter gives the position of the tolerance zone (H = hole at zero), the number the IT grade (precision). H7 is a widely used hole tolerance.
Difference between transition and interference?
A transition fit (k6, m6) may give slight clearance or slight interference; an interference fit (p6, s6) always has interference and needs pressing or shrinking.