Originally Posted by Kai Ju
I would have thought that if the tooth angle is different that non matching gears would not engage the same depth as matching ones. What I'm getting is that You have a couple of shafts in your hand and you're trying to figure out whether you can replace one with the other by engaging the two gears and looking at how deeply they engage. I'll probably be doing that on Saturday since I have to replace the gear on an input shaft and will be looking at some used shafts to source the parts from.
That isn't it at all. Non matching gears engage the exact same depth. They just touch each other at a different height on the teeth. You can't see it the way you are describing it.