Hi all. 

I'm learning how to do this gears tool and I'm stuck with the part of making sure that the angles on both bevel gears match.  I'm not even sure how to ask the question.  All I want is for both gears to fit in a 90-degree angle.  Normally, which part of the property that needs to be tweaked in order for the gears to be able to match nicely.  Is there some sort of best practice that I need to know other than seeing with your eyes whether the gears fit perfectly? Please advise?