Basics of Measuring GD&T Runout on a Shaft

[Music] you run-out is caused by a bent shaft or by eccentricity of the coupling eccentricity literally means being off-center it can occur if the coupling is not bored in its physical center or if the bore is bigger than the shaft and the set screws pull the coupling out of Center when measuring run-out the dial indicator is mounted to a fixed point in space if the coupling is disconnected attach the dial to the shaft opposite the one you want to check or if the coupling is connected you can use the mag bracket to mount the dial indicator to the base of the machines or any other fixed point in space we recommend that you first check for run-out at the hub or rim of the coupling because there you will pick up both eccentricity and bent shaft some people will also measure run-out in the axial direction which in addition would tell you if the coupling bore is skewed before taking the readings make sure the dial is mounted perpendicular to the shaft set the plunger to half its travel range to assure both negative and positive capacity once the dial is affixed rotate the shafts make sure you rotate in only one direction find the greatest distance from zero in either positive or negative direction stop rotating the shafts and reset the dial to zero now continue rotating the shafts and watch the dial for the maximum amount of change which equals the total amount of run-out if the run out is within acceptable limits at the hub mm ufff and the shaft is reasonably straight and within acceptable limits in this case the dial is indicating excessive run out of 20 mm X need to determine if it is being caused by a bent shaft or by an eccentric coupling or both we achieve this by repeating the same measurement process at the shaft you'll want to take the measurement as close to the coupling as possible in this case there is 21400 observe a situation where both conditions occur a bent shaft and an eccentric coupling if excessive run-out is present it should be corrected before attempting precision shaft alignment [Music] you

Channel: Engineers Edge

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Keywords: runout, gd&t, measuring

Id: gKCbsWXam8M

Length: 3min 49sec (229 seconds)

Published: Wed Oct 12 2016