Size: 3/8 inch [9,5mm]
Most mortisers are equipped to handle 1/4', 3/8', 1/2' and 5/8” square chisels.
Converted to metric: 6,35mm, 9,5mm, 12,7mm and 15,9mm.
Some are even capable of handling a 3/4' chisel, but keep in mind that this is a pretty healthy chunk to cut at one time and may require a lot of physical exertion. Remember that even if you're cutting a mortise that is 3/4' wide, you don't need to cut the entire width in one pass. A few cuts down one side of the mortise and then back up the other with a 1/2' chisel will be just as effective and not nearly as taxing on you as the operator.
- Faster than a chisel by hand
- Consistent in size
- Strong joints
- Reliable joints
- Looks good
- Large glue surfaces enhancing the strength
The hollow square mortise chisel
The hollow square mortise chisel is used in a drill press attachment or mortising machine, similar to a drill press in many respects, combines the cutting of a four-sided chisel with the action of a drill bit in the centre. The bit clears out most of the material to be removed, and the chisel ensures the edges are straight and clean. This device was invented in 1874 by Robert and Ralph Greenlee.
Square chisel mortising bits can also be fitted to normal drill presses using a mortising attachment as shown on the left. [Click here to view] - Available from Tork Craft.
The chisel kit is made from a square, four sided chisel with an auger bit inside. The auger bit is sized perfectly to fit inside the four sided chisel. The machine spins the auger bit removing a circular column of material and the chisel comes up behind it to square away the rounded edges. The way the chisel works is through downward pressure by the user. The harder the wood, the more difficult it is to plunge down. At the end of the process you get a really clean mortise.
Mortise and Tenon joints are strong and reliable joints. This joint can be seen in timeless furniture pieces and is testimony to its long-lasting capabilities. This joint gives support from all sides and has a large amount of glue surface.
When working on a project that calls for multiple mortise and tenon joints, hand-cutting them all would involve tedious hard labour, resulting with inconsistent joints. In a situation when you need to produce multiple mortises, there is no better option than a hollow-chisel mortiser.
YouTube Assembly demonstration of the hollow square mortise chisel