I’ve a bunch of offcuts from when a long fence was installed and there’s enough to make a reasonably large planter. To ensure it is strong enough my plan is to use mortice and tenon joints. I had made a couple of test joints by hand but it was quite time consuming and the results were far from perfect.
So I decided that cutting these with the router would be a better option and as I had a 16 joints to make a jig seemed like a worth while investment.
I started with the mortice jig. I knew I’d need some kind of clamp to fasten to the work so I used an offcut from the gates project and sliced it in half to make 2 L shaped brackets. Using the milling machine I cut a slot in this. I also flattened the heads of a couple of coach bolts. A slot was cut in a sheet of MDF and counter bored holes were made using a spade drill bit. The brackets were fixed using nuts and washers. The jig can be fastened to the work using a clamp or in the workbench jaws.
This jig is made from 3 pieces of wood screwed together and some hardboard as a backing plate. The hardboard is tacked to the right of the board only this allows the left hand end to be squeezed in the workbench to clamp the end stop in place. The end-stop is a simple block of wood.
My first pass at routing the tenon was a fail in that the wood slipped in the jig and I ended up with an angled tenon. It also took me a while to get the depth of the cut correct. But once that was dialled in, I produced a tight fitting and square joint. I’ll may need fix the joints with an additional screw as there could be seasonal changes in the wood. But I think I’ll see how it goes.