Flat Framing Joints
Thursday 06 May 2010
Anthony Bailey runs you through the jointing options for frames
As always, there are various ways to do the same thing, and framing joints are no exception. Here we show you the common types and the requirements for achieving them.
Mortise and Tenon
The mortise and tenon is the oldest and most effective method of jointing components at right angles. For light frames such as the shutter project, it is enough to have a stopped joint i.e. the tenon doesn't go right through so the mortise isn't very deep. You can chop out the mortise with a mallet and chisel, or use a router with two fences and a long straight cutter. The tenon can be done with a tenon saw or on a well set-up bandsaw.
The corner bridle isn't a locking joint, but the large glue surfaces mean it will be hard to break apart once set. Again, a choice of tenon saw or the bandsaw will allow you to cut both halves of the joint. You need accurate marking and cutting for a tight joint. If necessary, use a wide sharp chisel to ease the fit, then just add glue and check the joint with a try square.
Dowels are an old idea but they still work well, provided you can use them accurately. It is easy to misalign the holes and get a bad fit. Although you can use proper 'dowel points' for marking from one already drilled set of holes, drilling on the resulting with proper brad point drill still causes the drill to wander due to the wood grain. It works vastly better by using a proper dowel jig which guides the drill precisely.
A biscuit jointer allows very quick, accurate slotting so it should be good for a frame joint. However biscuits do not penetrate deeply and as a result, can allow a joint to separate easily due to force being applied. The joint improves if the centre panel is a tight fit, as it will help keep the frame square. It is a joint method better suited to smaller frames.
A newer development is the Festool Domino jointer, which machines slots for Domino joints. It is an expensive machine but once bought, it turns out what are effectively loose tenoned joints very quickly and repetitively. It is strong and accurate and suits many projects, as it can machine different size joints.
Tongue and Groove
A type of router cutter, or pair of cutters, that produces a simple tongue and groove, including the panel groove in the same operation. Not a deep joint, but the panel will contribute to the strength of the framing. Very quick to use once set up, and test joints made first to assess the fit. Suits the simple 'country' look or Shaker styles.