MR-1 - Coplanarity Check Gage

Regular price $19.95

Bring the MR-1 CNC Gantry Mill into Performance Alignment.


  • Check Gage

The Coplanarity Check gauge is a simple device that is used along with a Dial Indicator to measure coplanarity error between the Y Axis Rails. The Y axis rails are meant to lie in the same plane and any deviation from this condition is called coplanarity error. A machine with coplanarity error will tend to produce faces that have a corresponding flatness error.

As assembled, the Y Axis rails will have a typical coplanarity error that is no greater than about 0.001” per inch. As an example, if you faced a 5” x 5” block of aluminum and then placed it face down on a granite surface plate, it would show about .005” of rock. For many, this flatness error may be acceptable, but for those that want to fine tune their machine for greater accuracy, the coplanarity check gauge is needed.

The gauge is placed on the Y axis linear rails in a diagonal orientation. A dial indicator is positioned to sense on either the upper or lower centerpoint on the gauge and then zeroed out. The gauge is then re-orientated along the other diagonal line with the dial indicator tip again sensing on the centerpoint. A dial indicator reading of zero would mean that the Y axis rails are perfectly coplanar. If the indicator is reading 0.005”, for example, then 0.005” thick shims are required between the Y axis rails and the rail mounts at the appropriate diagonally opposed locations to correct the error. Household tin foil or printer paper is a very effective shim material that we recommend for any corrections. Full instructions for this process will be available in the assembly manual.