Cutting Angles Sharper than Forty-Five Degrees

Wall intersections tighter than 45° call for tricky chop-saw technique. Here's advice on jigs from a few trim carpenters. June 16, 2010

I am currently building a stair case that will require me to miter the end of 1 1/2 inch square stock at an angle greater than 45 degrees. I was thinking of building a wedge shaped fence for my miter saw to increase the angle. Does anyone have any other ideas?

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor V:
It doesn't always require a wedge shaped fence to cut odd angles. Sometimes what works is a fence that holds the edge of your stock @ 90 degrees to the chop saw fence. When you do that the zero degree mark on your saw is truly zero degrees to the edge of the stock. Cutting like this usually requires you to clamp the stock while making your angled cuts.

From the original questioner:
Thanks contributor V that is a much better idea. I'll give that a shot.

From contributor H:
A few years ago at one of the wood working shows I bought a protractor made of aluminum. It's about 10" long, graduated in 1/4 degrees, closes to 30 degrees and opens to 90 degrees. It's an I beam type construction. I can clamp it to the fence of my miter saw and then set the corresponding angles. The outside flanges make a good surface to clamp the part to.

From contributor K:
I saw in a woodworking magazine a few years back where they used a tenoning jig used on a table saw to cut steep angles. The blade is set at 90 degrees and the jig is adjusted to create the angle. It is very safe and accurate.

From contributor R:
To the original questioner: your initial idea wasn't too bad either. I regularly make a simple jig for my sliding compound miter saw for cutting long acute miters. Just take piece of 1/4-1/2 ply about 12W x 24L and place the long side against the fence. Just glue/brad/staple a piece of 1x to the plywood at a 45 degree angle from the fence and the blade. Clamp the plywood to the saw or table and use the 1x as a fence. With the jig holding the material at a 45 to the blade to begin with you can just turn the blade into the material for >45 miters.

Two things to look for: you might need to slide plywood back/forth along the fence to the end of the 1x fence with the blade properly. Depending on the depth of your blade and the thickness of the material, you might need to adjust the thickness of the plywood in your jig. I usually use this jig for cutting long crown miters. I cut crown laid flat on the saw. You would have to create a vertical fence on the jig if you cut crown 'standing' against the fence.

From Gary Katz, forum technical advisor:
For your chore, I'd suggest taking two pieces of 1x12 or plywood. Cut one at a 45 degree angle. Leave the other square. Sandwich them together so the 45 is on top, about four or six inches back from the square cut one. Then place that jig on your saw and set your molding against the new 45 degree fence. That way you can clamp the jig to your saw, and you can clamp the molding to the jig (the bottom 1x12 is there just to hold your clamp). That's the safest way to use an acute angle jig. I've seen lots of stair builders use the same type of jig for cutting the scotia molding that runs along the bottom of the skirt and miters to the basecap scotia.

From the original questioner:
Thanks for everyone’s input. I think I have a grasp of how to handle this now. I came up with a method incorporating ideas from everyone.