differance between 14.5 and 20 degree Pressure angle gear cutters

Any one know how to tell the differance between 14.5 and 20 degree Pressure angle gear cutters, of the brown and sharpe pattern.
I have some that are marked 14.5 PA some 20 and some no marks (all Mod 4)
Steve larner
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Rather like the difference between metric and BA screw threads, in that the principles are the same, but not the measurements.
If you could get them to work together (and I don't know the answer 'cos they might bind) then you'd have increased wear and noise because you'd get sliding and not rolling contact.
What is the pressure angle?
Imagine two gear wheels in mesh.
Draw a line joining the two centres.
Imagine two of the teeth in contact exactly at the point of crossing the line.
Then the tangent of the point of contact is at that angle to the line joining the centres.
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OOPS! SORRY! I was talking about gear wheels and not their cutters, but the principles discussed below would apply to any gears you tried to cut with the cutters

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Anonymous. Wrote: > OOPS! SORRY! I was talking about gear wheels and not their cutters, but

> no angle so i want to determine which set they belong to.

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Why not try the old trick of rolling each gear through a pit of plastiscine and then measuring the angle of the teeth in the plastic rack you have created, Peter
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