Thanks EdB

I always figured too small of hole led to mushroomed thread edges. Not sure if they said that or not.

Problem I always have w/homebuilt stuff, like tapping holes, is I don't know how much IS enough for strength. If I think 2x2x3/8 angle will work, then I use 2x2x1/2 angle. I always worry about undersizing. I realize mfg have a different criteria & need to use the smallest things possible, for cost reasons. Same w/thread depths. I have no proof that 1.5x thread depth is enough. So...I'll go for minimum of 2x depth. Then I can sleep @ night.

BTW-I almost have tapped hole problem solved.