[Willie T]

What you are most likely experiencing is a common situation where the wall is not flat. To understand what I mean, cut two good 45's on your miter saw. Now place them together on a solid, flat table. They should fit perfectly (or as perfectly as your saw will cut them... don't forget a saw can be off)

Now, take a dime, and slip it, lying flat on the table, under the inside corner of the joint. See what happens to that perfect joint?

Next, take the dime out, put the joint back together, and now slip the dime under the point (outside) of the joint. See how the joint opens up again.... but this time in the opposite direction?

Frankly, there's not much you can do about these conditions other than to either learn (it takes a lot of practice) to sense the tilt of a wall at a joint and compensate as you cut (kind of tough to do, and harder to explain).... or just try some thin shims under your joints as you put them on the wall. Experiment to get the feel of this.

If your saw is cutting correctly, this is probably just a matter of uneven corner wall surfaces, nothing more.

BTW: This is usually caused by the way the corner bead sits "proud" of the wall by an eighth of an inch or so.... and the bugger is that both sides of the corner are seldom off by equal amounts. :furious:

 

[Willie T]

Willie, your answer is most of the time EXACTLY what is happening.. but i didnt want to bring that up in this thread.

yes, many times when i i've put sheetrock up if i'm not exactly "rock depth" on my window frame i just say "eh, the trim will cover that."

but then it messes up all my angles. You are 100% correct.

Sad thing today is all the isolated "specialization' of the various trades. Few younger guys (and gals) have the slightest idea how much the correct installation or application of their part of the job effects so many other trades persons.

"Back in the day" we did just about all of it ourselves. So we often, and quickly, learned that we had to do it all correctly....... or we would be paying for it a little further on down the line.