With the sides completed and the other components cut close to final dimensions I proceed to cut all of the grooves using my tablesaw and a dado stack. My saw till design requires 1/4″ grooves on several pieces including the inside of the till sides, the top and bottom rails, and all the stiles for the back panel. If I were only cutting grooves in the stiles and rails I would approximately center the dado head on the stock and then make two passes, one with each face against the fence. This ensures that the groove is centered and it makes mortising much simpler later on.
I can’t use that approach on the saw till since I have to cut grooves on the sides. With the curved profile and the groove offset to the back I obviously can’t flip the sides to center the groove. Therefore I select and label all of the face sides of my components. Since I have to route the groove in my sides with the back edge against the fence I make sure to run the grooves on all of the rails and stiles with the back face towards the fence. This way any discrepancies in the centering of the groove on the stock will all stack to the same side.
With the grooves cut I turn my attention toward cutting the mortises within the groove. Typically I would cut my mortises using my hollow chisel mortiser. However on this project the sides were too wide to fit within the clamping area and the top and bottom rail were too wide to fit under the chisel. This left me with two options to cut the mortises – use a router or a chisel. Since I dislike balancing top heavy routers on the sides of narrow boards while chips hit me in the face I opted for the chisel approach. The router probably would have been faster, but the chisel allowed me to listen to a new CD I purchased while doing the work.
Chiseling by hand isn’t too difficult in this project since the mortises are fairly narrow and shallow. Using a softer wood like poplar also makes chopping the mortises a lot easier. If I was using hard maple I probably would have gotten out the router. The grooves that were cut on the table saw can be used as guides for most of the mortising - as long as you have a chisel which matches the width of your groove.
While chiseling the top and bottom rails I clamped the rails together with handscrew clamps and then clamped the handscrews to the bench. This keeps the rails stable while mortising and prevents tipping. A dedicated mortise chisel helps immensely with this type of work and I used one of my Ray Iles pigsticker chisels. The trick with mortising is to make a series of shallow cuts which define the mortise. Stop short of both ends of the cut so that you can use those edges for levering out the waste. From there it is just a lot of bashing and prying. Draw a line on the back of your chisel with a sharpie marker to act as a depth gauge.
Chopping the mortises in the case sides is a little bit trickier since I am using through mortise and tenon joinery and the mortise edges will show. Therefore it must be as clean and precise as possible – this is a little tougher when chiseling by hand. First mark out the edges of your mortise using a marking gauge. You can set your marking gauge to the edges of the grooves on the inside faces of the saw till sides. Try to go as deep as possible with the marking gauge since this will result in a cleaner surface. Take your time on the first pass of chops and be as accurate as possible. If you get past this stage cleanly you are almost home free. Since the inside of the grooves will be hidden I bashed the waste through rather than prying it out in an attempt to keep the show face cleaner. Just make sure to make cuts at the ends of your mortise within the groove to avoid blowouts in the grooves as you chisel the waste through.
With the mortises cut I went back to the tablesaw to cut the tenons. Since the top and bottom rails are almost 10 inches wide cutting these tenons by hand is pretty much out of the question. If you have a dado stack and an accurate miter gauge you can cut very accurate tenons with exceptionally clean shoulders. Make sure to sneak up on the cut and use a test piece to check your progress – don’t forget that the grooves may not be centered so if you didn’t quite get nail the location then you will need to cut the face cheeks and the back cheeks with separate setups. I was close enough so I used a single setup and will just plane out any small discrepancies on the panel once it is glued up.
Make sure you cut all of your parts at once. I lost a stile somewhere along the way and didn’t realize it until I had torn down my setup and put back my dado blade. I ended up cutting that tenon by hand rather than setting everything back up because it was quicker.
The tenons on the top and bottom rail are split with a shoulder in the middle. This is necessary due to the difference in grain orientation between the rails and the case sides. One wide tenon glued into the case side would be likely to split down the road. It would also significantly weaken the case sides since the tenons are through tenons. With the cheeks already cut on the tablesaw I finish the tenon cuts using backsaws and a coping saw. Notice my newly made Moxon twin screw vise. I still need to get around to writing that post.
With all of the mortises and tenons cut I did a a dry fit. I had to touch up a few tenon cheeks here or there with a shoulder plane, but everything went together well. You can see the dry fit of the top and bottom rails into the sides below. I forgot to take a picture of the dry fit with the stiles in place.
Here is a close up of one of the through tenons without glue. Not too shabby for a hand cut mortise.