Posted by T.Fujikawa on May 28, 2009 at 09:16:52:

In Reply to: Re: Test radius posted by Tom Ramsey on May 26, 2009 at 10:06:33:

Thanks so much for kind advices.

Please kindly give me further advice to the following further question.

Definition of ‘ test radius ‘ :

Test radius of a gear is defined as meshing pitch radius ( 1/2 of meshing pitch diameter) of a gear when standard tooth thickness ( 1/2 of a pitch) of the same module, pressure angle, and helix angle of the gear is meshed.

I understand that if center distance is set as theoretical test radius of a gear plus actual test radius of the meshing gear (master gears) on gear rolling tester, measuring results of ‘Test radius’ of a gear to be measured should be theoretically same even if different test radius, number of teeth, and also addendum modification of the meshing gears (master gears) which have the same pressure angle and helix angle.

Actual measurement results may be almost same and not just same.

The difference of them can be negligible for actual use of it because it comes from a difference of a few no. of teeth at master gears.

Please correct my above understanding if wrong and let me know the formula for calculating of test radius using gears data of

a gear and meshing master gear including pressure angle, helix angle,

Looking forward to helps,

Best regards,

T.Fujikawa