Shim Calculation Geometry

The shim at each foot corrects for both offset and angular misalignment:

Where offset is vertical displacement at the coupling, and angle is the gap difference divided by the coupling diameter, projected to each foot distance.

Standard Shim Sizes

Thickness (mm)	Thickness (mil/thou)	Material	Color Code
0.05	2	Stainless steel	Gold/Yellow
0.10	4	Stainless steel	Orange
0.125	5	Stainless steel	Purple
0.25	10	Stainless steel	Red
0.50	20	Stainless steel	Green
0.75	30	Stainless steel	Blue
1.00	40	Stainless steel	Silver
2.00	80	Stainless steel	Brown
3.00	120	Mild steel	—

Alignment Tolerances by Speed

RPM	Max Offset (mm)	Max Angularity (mm/100mm)
600	0.10	0.10
900	0.07	0.07
1200	0.05	0.05
1500	0.05	0.05
1800	0.04	0.04
3000	0.03	0.03
3600	0.025	0.025

Shimming Best Practices

• Always use pre-cut stainless steel shims — never cut your own from sheet metal
• Remove any existing paint, rust, or burrs from the foot and base before shimming
• Check for soft foot before beginning alignment (tighten one bolt, measure gap at others)
• Use the minimum number of shims possible — combine to use 2–3 shims max
• Shims must be clean, flat, and the correct size for the bolt and foot
• After shimming, tighten bolts in a cross pattern to rated torque
• Re-check alignment after final tightening — shimming can shift during torquing
• Document all shim changes in the alignment report

Thermal Growth Compensation

For hot-running machines, account for thermal growth. The motor may need to be set LOW at ambient temperature so that thermal expansion brings it into alignment at operating temperature:

Δh = α × L × ΔT, where α is the coefficient of thermal expansion (~12 μm/m/°C for steel), L is the distance from base to centerline, and ΔT is the temperature rise above ambient.