Adding detail to box corners really makes them stand out and helps to reinforce the edges as well. Adding Dovetail Splines is one way of adding detail but it does take a degree of patience, and you need to select the correct accessories and woods to make this job go smoothly and by reading this you will see some of the challenges I encountered and what you can do to help eleviate them.
Watch the video on Youtube Here: https://youtu.be/Te0NsctAtb4
The first thing that needs to be done is to make the jig. I made mine from good quality 1/2" plywood. I cut a 4 inch wide strip and after cutting that strip in half I had 2 - 1/2"x12"x4" strips. I glued the edges together at 90 degrees, making sure that the angle was exactly 90 degrees, you can see all the clamps I used to do this, I used my doweling jig to ensure the edges were aligned. My plywood was slightly bowed so I needed to ensure that the angle was correct and the wood was straight.
As you can see in the video, I also took some of the point off the bottom of the jig before assembly because it is not needed and because the dovetail router bit I had only had 1/2" height of the actual dovetail piece. after the trimming I fastened the edges on and made the side that will ride against the router fence about 12" long because I wanted a longer smooth edge as a guide.
After the jig was made I took my sample corner, adjusted my dovetail bit in the router table as best I could and began to run the first cut. The bit stopped about halfway through the first cut. The reason for this is because I had the bit too high and although the top of the bit was cutting into the jig and partially into my sample corner, the reason it stopped was because the shank was above the router table and of course would not cut into the jig's base. I lowered the router bit and tried again, still to high so I lowered it slightly again and the final cut went through as it should.
The cut made with the dovetail router bit looked fine. My next challenge now is to make a sliding dovetail blank that will fit snugly into the dovetail slot I just cut. This is where the patience comes in. There is no way that I know of to make the dovetail blanks except trial-and-error cutting. I know that the dovetail bit has a top radius of 1/2" so I decided to cut my blank material at that width to see if that would help with the alignment. Not really, it still takes time, setting, and re-setting and running pieces of wood through until you get one that fits. I did mine it 3 tries but it could have easily been more.
The wood I was using was very chippy when I ran it through the router table. There was no sawdust, just chips of wood and some of them large. This resulted in less than idea dovetail blanks, but they were usable. I think the type of wood I was using combined with the cut of wood that I had combined to make this chippy type of cut. In the future I would try to secure other wood that may help to reduce the chipping and produce better, smoother dovetail blanks, and hopefully I can find this wood in a dark color for the contrasting look I want to achieve.
The next part was easy, glue one end of the dovetail blank into the dovetail slot and let it dry so that it could be cut off, which is what I did. I selected my finest "draw saw" and proceeded to cut the dovetail blank even with the face of the boxes at the corners. The first side came off fine and despite the fact that the video is speeded up, I did take my time to get a nice clean cut. I then flipped the box over and cut the second side off and to my horror, I could see as the side flipped off, that a small chunk of wood came off with the scrap material I as cutting. It was very tiny, but saw it come off.
What I Learned ...
First of all, the dovetail bit I used was not ideal. Dovetail bits come in a variety of angles from 8 degrees up to about 16. The one I was using was a 14 degree angle, which was fine but the problem with my bit is that the carbide or cutting edge of the bit is only 1/2" long so the deepest dovetail it will cut is only 1/2" deep, and that's if eveything aligns perfectly, which it may not on the corner of a box. I did some research on dovetail router bits and I think the ideal bit would be the Freud bit number 22-128, which has a 1/4" shank, a 14 degree angle and has 7/8" of carbide cutting edge and the total bit legth is 2-3/8 inches. This would give a lot more allowance for cutting dovetails of different depths.
The second thing I would spend more time with is trying to find a dark colored wood with a much finer grain, and preferably something that is quarter sawn. I think finding a board like this would help reduce the chance of wood chipping out at the corner of the spline. There really is not a lot of wood to hang on there, no matter how the wood is cut so a finer grain wood would be one way of helping to firm up those corners.
Here is where taking time to select the right wood for a job like this becomes critical. I used the only dark colored wood I had on hand and really was not suitable for this job. It's a coarse wood and the board is "rift sawn" "quatersawn" would probably have been better.
Like many things we do in woodworking, the learning and trying are half the fun, the other half is figuring out how to make it better and consistent and that will be my goal in the future because I love the look of corner dovetail splines and I think there are way and other jigs that can make this process easier are repeatable ... and that will be my goal.
Copyright Colin Knecht