keyway gaging on shaft 1

[tfstr6]

I am looking for a repeatable and easy method for gaging the critical dimensions on a small diameter driveshaft. Centerline, depth, parallelism. Any suggestions would be appreciated.

 

[Skogsgurra]

If it is a small diameter shaft, then an optical system seems to be the best choice. A little "web camera", suitable optics, a monitor, a sheet of translucent plastic and a precise grid for calibration and a stable fixture for camera, grid and shaft is what you need. The optics must be selected to give the necessary magnification. Ideally, the keyway shall take up most of the screen area.

Put the grid in the measuring plane, attach the plastic sheet to the monitor and trace the grid lines on the sheet. This will give you a fairly accurate optical micrometer. Then place the shaft in the same measuring plane and take your readings. This method works well for width and parallism, centerline needs the calculation of two points (mean value of wall positions). Depth could be measured by moving the object or camera back and forth and observing the sharpness, but that seldom gives the precision needed. A light wedge (a narrow, strong beam of light) that is adjusted to hit the bottom of the keyway at 45 degrees angle will give the depth if the center of the shaft is fixed.

There are, of course, machines that do this automatically. like OGP, but for short runs and limited budgets this simple solution is probably better.