Introduction • On Precision Pots • General Product Definitions • Construction Details • Multiturn Precision Pots • Resistive Elements • Terminals • Shaft-Rotor Assembly • Mechanical Rotation • Mounting Methods • 3540 Family • 3590 Family • Knobpot 3600 Family • Single-Turn Precision Pots • 6537/6637 Family • 6539/6639 Family • 3680 Pushbutton Family • Special Precision Pots • Shafts • Mounting Styles • Bearings • Torque • Linearity • Wiper Load • Low Current Applications • High Rotational Speed • Angles • Additional Taps • Sealed Units • Multicup Assemblies • Envelopes • Environmental • Competition • Useful Terms

Mounting Styles

Bushings

Whenever possible, utilize standard bushing configurations. Non-standard materials, lengths, diameters, threads, and other modifications are available at an additional cost.

For example, optional split-lock bushings are available for applications requiring that the shaft be locked after adjustment. External locking mechanisms are available for use on standard units.

Custom bushings must have the following specifications:

  • Length (l) of the bushing from the mounting surface (FMS), including the tolerance
  • Diameter (d) of the bushing, including the tolerance
  • Thread pitch (p)
  • Special coating for environment as required
When specifying maximum bushing lengths, it is important to be aware that many models use a "C" ring, which is mounted on the shaft at the end of the bushing. Space for the "C" ring requires a nominal dimension of 0.035" (0.9mm).

Servo Mount Lids

For cost control and maintaining tight tolerances, designers are urged to utilize Bourns standard lids, particularly if the need is for fewer than 100 pieces. If a custom lid is necessary, be sure to specify all dimensional requirements.

As with shaft diameters, over-specification of tolerances can become very costly. For example, tighter-than-standard lid pilot diameter and lateral runouts will add significantly to the cost.

Servo mounting clamps are available for all servo lid models.