# Compound miter cut

## Compound miter cut (post #215060)

I am installing chair rail and have a couple areas where the chair rail runs horizontal and then at the stairs it turns the outside corner and goes up the stairs (and down the stairs at another location).

How do I go about calculating the tilt and miter settings for cuts like these? I know the horizontal outside corner will be a regular 45* cut but am not sure how exactly to set the saw for the adjoining cut?

Was hoping to find a chart or something to go off of once I measure the angle. No luck.

Mic

### There are theoretical ways to (post #215060, reply #1 of 6)

There are theoretical ways to do it, but, regardless, always make up a sample piece before you cut the good wood.  Among other things, that 45 degree angle might actually be 47 degrees, and that little bit of error can leave an ugly gap.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

### Ok, I appreciate the (post #215060, reply #2 of 6)

Ok, I appreciate the opinion, but do you have a suggestion that would help me?

### Turn the corner with a short (post #215060, reply #3 of 6)

Turn the corner with a short piece, bevel cut at 45 deg.

Then miter cut for the rail to go up / down the stairs.

You cannot go around a corner and change slope with a single cut.

### Thanks for pointing that out. (post #215060, reply #4 of 6)

Thanks for pointing that out. I didn't realize that. Guess that's why I haven't been able to figure out the proper cut.

So, if I understand correctly: run horizontal piece to corner-make a small piece to turn the corner (on the same horizontal plane)-then miter angle for vertical cut (runng up/down stairs)-then cut small piece to return to horizontal plane, before turning the corner again (back to horizontal plane).  Is this correct?

### Yes, that is it.Â  Just to be (post #215060, reply #5 of 6)

Yes, that is it.  Just to be sure, see attached sketch

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CORNER_TRIM.pdf7.86 KB

### Thanks Cat, worked out fine. (post #215060, reply #6 of 6)

Thanks Cat, worked out fine. Really appreciate when someone gives clear straight forward techniques instead of useless blather.

Many thanks!