Question

Can somone show me how to do the 1st problem? Need to find the LS and SS for the fit and the LH and SH for the hole.

Fits are all SHAFT BASIS METRIC but the shaft and hole diameters can not be used right out of the table. This is because the 3mm shaft tolerance does not match. You will need to lookup the "Fit" from the table, and then use the LS (Largest Shaft) and SS (Smallest Shaft) to calculate the LH (Largest Hole) and SH (Smallest Hole). These fits are on Pages 657-660 of the Machinery Handbook excerpt that you were given, and is on BlackBoard. Min Interference LH- SS Max Clearance = LH - SS Max Interference = SH - LS Min Clearance = SH - LS Put a different way: LH = Min Interference + SS LH = Max Clearance + SS SH = Max Interference + LS SH = Min Clearance + LS 917-006 White Gear to 3mm Shaft Free Running Fit Page Number Shaft Fit Hole LS SS 3.008 LH SH 3.002 917-007 Red Gear to 3mm Shaft Force Fit Page Number Shaft Fit Hole LS 3.008 LH 3.002 SH SS

Answer 1

Dear Friend,

Reference to the question no 1,

The Fit preference is already stated as "free running fit"

As per the shaft basis system, the ISO symbol of the free running fit is "D9/h9" (Preferred)

As LS = 3.008 mm and SS = 3.002 stated, we can say the nominal size is over 3 mm to 6 mm band.

As per the requirement of free running fit, (as per D9/h9)

Maximum clearance required = 0.09 mm

Minimum Clearance required = 0.03 mm

Hence,

LH (Hole) = maximum clearance + SS = 0.09+3.002 = 3.092 mm (Ans)

SH (Hole) = minimum clearance + LS = 0.03+3.008 = 3.038 mm (Ans)

LS (shaft) = 3.008 (free running fit) (Ans)

SS (shaft) = 3.002 (free running fit) (Ans)