Does measurement performance vary with Rotor to Stator gap?

Resolution, repeatability & linearity will be as specified, provided gap is within 1.10+/-0.35mm. Within limits, the IncOder’s measurement resolution and repeatability are independent of air gap.  If the air-gap tolerance is increased from ±0.35mm to ±0.50mm the quoted measurement non-linearity will double.  For example, if a 250mm IncOder has an air-gap tolerance of ±0.50mm the quoted linearity will increase from +/-40 arc-seconds to +/-80 arc-seconds.

If the quoted linearity is required then the specified air-gap tolerance should be maintained.  This is most easily achieved using the Set Screw Rotor whose axial position can be readily set.  Preferably the Rotor’s inner diameter should be a close fit to the through shaft.  Alternatively the required gap may be maintained by the use of a shim.  Peelable shims are available as an IncOder accessory.

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