Cutting Acute Angles

By Robert Robillard on Product News, Workshop tips

Acute Angle Jig – Accessory fence

There are many times that I find I need cut trim or molding at an angle greater than my miter saw was designed for.  Most miter saws cut to 45 degrees or slightly larger, usually 50 degrees.


But what if you need to cut 55 degrees or a greater angle?  Cutting Acute Angles means a greater angle and one that miter saws can not give you without assistance.

One very dangerous way is to hold the piece to be cut perpendicular to the saws fence and freehand this cut. I do not recommend cutting trim this way. A safer solution is to make an acute angle cutting jig and keep it with your saw.

Acute Angle Accessory Fence

On a recent project I needed to install trim on  trapezoid style windows and built-ins. This meant that the trim angles were going to be larger than my miter saw was able to cut.

I constructed an acute angle jig, accessory fence form my Dewalt miter saw. This fence consisted of a 1/2 Birch plywood bottom and 3/4″ triangular sides. Two meet at 90-degrees and the third side connect s the two at 45-degrees. the 3/4″ parts and glued and nailed to the 1/2 plywood base.

The jig clamps to the miter saw fence, in line with the saw blade set at 90-degrees. I also used the saw hold-down, for extra support. Additionally I use a third clamp to hold the molding to the jig fence.


The result is a piece of base cap cut to 67.5 degrees.

Cutting Acute Angles with A Jig – 90 Degree Fence Version

I made this older acute angle jig,  out of scrap wood.

I arbitrarily chose 12″ x 12″ for this jig. I cut a 12″ x 12″ piece of 3/4″ plywood and then cut it diagonally to make a brace for this jig.

Scrap 5/4 trim makes up the edges. I chose 5/4 sides because the raised edges give me plenty of space to clamp or screw this jig to my miter saw table.

I clamped and screwed the parts together at 90 degrees.

The goal here is to make an auxiliary fence jig that can be clamped or screwed to my miter saw fence. Below checking for square. [90degrees]

A bar and spring clamp hold the jig to my miter saw fence for a trial fit.

Trying out just spring clamps… quicker but not as strong as a bar clamp. I’m getting thirsty looking at that ice coffee in the background!!

Once the jig is secure the trim is held tight to the jig and the saw can be adjusted to much greater angles than if you used the saws fence.

Test cut at 55 degrees.

Here’s another version of the fence I recently made

~ Concord Carpenter

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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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