Timber Frame—Cutting a Knee Brace

Knee braces are needed to prevent a frame from racking in the wind.   Often the frame will be cut such that knee braces are the same size and any brace can be used anywhere on the frame.  The shed frame I am working on calls for  knee braces that are set at 45 degrees and have a 30” rise and 30” run.  The braces can be used in any position on the frame. 

These knee braces are 3” x 5”.  When I cut these on the TimberKing 1220,  I cut them at 3 1/8” x 5 1/8”.  This gives me a little room for shrinkage and when we assemble the frame for test fitting, they can be pared to fit if needed. Some guys run their brace material through a planner to make sure they are starting with stock that is dead on 3” x 5”. 

Drawings for Brace

All angles are 45 degrees.

Directions for Cutting the Brace

I normally cut with a circular saw and then finish the cuts with a handsaw.   Others might use a band saw or radial arm saw.  Whatever works is fine.  If you use a circular saw, before you start, make sure the saw blade is squared up.

 

Layout of the brace is conducted per the drawings above.  The layout is done by scoring the material with a razor knife.   The reference face will be the face that is cut away to make the tenon.   

 

Make sure the saw is set to cut right at 1 1/2”.  Cut the shoulder right along the scored line.

Cut the material that will be removed for the tenon.

Use the scored layout lines as a guide, break out the waste wood.

 

Pare the tenon to the line.  Use the small side of the framing square; verify the shoulder is square and the tenon is exactly 1 1/2” off the reference face.

Check the tenon thickness.  If necessary take a bit of material off the backside to ensure the tenon is 1 1/2”.

Knee brace tenon.

Checking the fit of a finished knee brace.