Measuring Rotary Knobs

Body Diameter

The body diameter is measured at the base of the gripping surface and excludes any non-grippable flange or skirt and also excludes any protruding pinters or tails.

Maximum Diameter

The maximum diameter is measured at the widest part of the knob and excludes any non-grippable flange or skirt and also excludes any protruding pinters or tails. The widest round part of the knob.

Minimum Shaft Depth

The minimum shaft depth is the minimum amount that the shaft must be inserted into the body of the knob, in order to make suitable contact with the shaft fixing.

Maximum Shaft Depth

The maximum shaft depth is the maximum amount that the shaft can be inserted into the body of the knob. This is measured from the lowest part of the base of the knob to the bottom of the hole.

Height

The height of the knob is measured from the lowest part to the highest including any pointers, inserts, skirts or domed end caps.

Clearance

The clearance is the space between the bottom of the knob and the equipment it is mounted to. While this is not a direct specification of the knob it is important to consider this dimension when selecting a control knob.

An appropiate level of clearence between the base of the knob and the surface of the equipment is nessessary to ensure smooth control and to prevent damage. If your equipment has a recessed area around the control knob shaft you will need to consider this in conjunction with the maximum shaft depth and maximum diameter.