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Saturday, June 18, 2016

Minor diameter of spline as the spline datum


Is it possible to use the minor diameter of a spline as  a  datum when the print requires to check the GD&T’s of other features to a spline datum?

In this days, it is known that the Spline Gauges are the best inspection tools to check the splines. Spline gauges have an advantage over old methods of checking spline dimensions because the use of spline gauges not only ensure the quickest process for acceptance, which means also less timing cost, but also eliminates the need to inspect the profiles with old ways such as three pins method, pin+dial indicator methods,etc.

 By using ‘GO’ and ‘NO GO’ spline gauges and plain ‘GO’ and ‘NO GO’  we ensure:

1    1)  ‘GO’ spline plug gauge checks the profile flank , the equally spiced angles  for all teeth, the extension of the root radius to the pitch circle diameter, pitch circle diameter and the runout of pitch circle diameter to major diameter of spline.

     2)  ‘NO GO’ spline plug checks the major diameter and space tooth width.

3   3)    GO’ and ‘NO GO’ plain gauges check the minor diameter of spline.


So, all gauges  ensure all dimension and fitting of the spline and among other dimensions also that the position of 3 min-pitch-max diameters to each other are within their tolerances. 


As a conclusion, when the GO/NO-GO spline gauges and plain plug gauges accept the spline it is possible to use the minor diameter of spline as a datum when the print requires to check the GD&T’s of other features to a spline datum. 

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