The best and most efficient way to mark out mortices for me is to use a story stick. It’s just a simple stick with all of the measurements drawn on to it so I can reference from either the top or bottom of the leg and mark on the appropriate line. I just make a little scratch on the leg and then go back to each with a square and knife to make the mark more defined. I like to use the knife as it enables me to sit the chisel right in to the line when I come to clean the joints up.
I decided to cut the mortices on the mortice machine as there was a fair few of them and they were big, deep and all the same. I opted for the chisel morticer as there’s a lot less clearing up to do than if I use the chain although to be quite honest cutting mortices of this size on the chisel morticer feel just as hard work as cutting them all by hand! Once finished on the machine I cleansed my soul and then cleaned up the ends of the mortices with a chisel and removed any crud from out of the bottoms.
I whipped all of the rails to length on the chop saw and marked out the tenon shoulders on the short rails just using a knife and square. I laid the rail end on to the mortice and eye-balled it central so I could put some pencil marks on the end of the rail for the tenon cheeks. Rather than bothering with with a marking gauge which might not have shown clearly in the end grain of the coarse oak I instead transfer my small marks right up and round the tenon being sure to keep the pencil line parallel by using my fingers as a fence. I cut the joints with a great big back saw; it’s sharpened as a rip saw but I cut both cross and rip cuts with it.
The long rails are a little bit different as the tenon only has one shoulder. This is for two reasons; one because the rail is thinner I feel it is stronger as the mortice can be sat back further in to the leg. Secondly when drawboring such a tenon it causes the back of the joint to pull in slightly tighter than the front and so creates a tiny bit of twist. Once the base is fully assembled this twist is pulled straight and leaves the base under a slight amount of tension which makes it stiffer. A lot of medieval furniture, tables etc used this – the rear shoulder was set in a lot more essentially not doing anything and this would create twist and tension in the joints which allowed them to get away without relying on the strength of glue.
On the long rails I just sawed the shoulders and split the cheeks off with a chisel, partly because the rail was too long to stand up right in the vice for sawing. I fine tuned the cheeks with a router plane, this is one of those tools that I absolutely love as it helps me to fine tune joinery very precisely. Once the joints were close I did a test fit of each and found that on some of them the rail protruded slightly from the face of the leg. To compensate for this I planed material off the back of the rail rather than the cheek of the tenon.
One of the joints seemed a little stubborn and I actually managed to get it stuck in the mortice! After I finally got it out and after a bit of head scratching it turned out that the mortice wall was tapered inwards so I squared it back up again with a chisel and the joint fitted fine.
Once I was happy with all of the joints I did a dry fit of the whole base, I am normally a bit of a bugger really and don’t bother with this stage – all seemed well. With the base back apart I drilled all of the peg holes for the drawboring along with any other holes in the legs for holdfasts and dogs etc. it was then time once again for the good old riving and preparing of the pegs for the joints. Finally, before I knocked it all together, I took off any sharp edges with a block plane and planed all the surfaces smooth.