Posted by Ron V on November 16, 2009 at 03:43:09:
In Reply to: Re: Topping hob question posted by Jim Pollock on November 15, 2009 at 08:54:08:
Your questions are not dumb......they are very appropriate.
The old standard was phased out sometime before the 70s or even earlier.......I'm not sure exactly for in the USA. Pretty much the rest of the world got rid of it around the 30s or 40s along with the imperial way of measuring.
Generally the two standards are interchangeable but it's always wise to check.
The shallower tooth depth won't cause any increase in noise as the depth of active profile is the same for either standard......only the clearances is different.