Knee Brace Tenon and Mortise 1 1/2″ Layout

Knee Brace Tenon and MortiseThis is an exploded view of a 3″x5″ knee brace tenon and mortise,  with tenon layout of 1 1/2″ off the face and 1 1/2″ thick, and its mortise in a tie beam.
The peg is 3/4″ in diameter and it’s placement is 1 1/2″ off the shoulder and 2″ off the bearing end.
The tie beam has been rotated 45° so you can see inside the mortise.

7 thoughts on “Knee Brace Tenon and Mortise 1 1/2″ Layout”

  1. Is it necessary to have the housing cut out to fit the full size of the brace into the beam? Or could you get away with just mortissing out for the tenon?

    1. You can omit the full housing but I would not recommend it as a general rule. The housing adds a lot of strength to the joint and it hides the gaps in the mortise as the timber dry.

  2. William H. Cary

    Do you offset the holes for the pegs in the mortise and the tennon and by what amount ? 1/8 inch?

    1. That is called draw boring and it is not always recommended to do. If you are using oak or equiv. you can do it but if you are using a softwood you have a good chance of blowing out the mortise rendering the joint useless.

  3. Braces have been found in old barns without any pegs at all. Braces work in compression. It is very unlikely, in my opinion, that you’d blow out the tenon with a 1/8″ draw bore in softwoods.
    I do draw bore brace peg holes. But I do it in two directions to help pull the brace to the housing and to the bearing end.

  4. When you mortice out for a knee brace is the mortice square or is it cut to follow the angle of the tenon on the brace? Thank you..

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