This is a follow-up to the Curtis Mitertite article by Dave Parker, and an attempt to answer the question about the feasibility of making this joint in the field. I previously posted some comments to Dave’s article and uploaded some photos of a prototype jig that I made with the resulting joint. This is a more detailed account of what I think a setup should be, taking into account the problems encountered with the prototype, and also addressing the need for different size casings.
As drawn, the jig should handle casing from 2 1/2 in. to 5 1/2 in.
The setup, as I envision it, would use two templates, and a template base, for each part of the joint, the leg and the head. These parts should be precision-cut, either on a mill, or with a CNC router. The rest of the jig would be shop-made from available materials.
The templates could be made of 1/4-in. melamine, plastic, or possibly 1/8-in. aluminum. The template bases could be made of 1/2-in. melamine or plastic, or 1/4-in. aluminum.
Let me say here that the drawings are done from theory, and may require minor adjustments to provide a tight joint after the first set has been cut and tested. The templates are based on using a bit and bushing setup, and require a 1/16-in. margin in the template. I used a 1/2-in. bit with a 5/8-in. bushing.
Now for the shop-made parts, and the setup of the jig.
We’ll start with the leg jig, which is the easiest. As my drawings show, the base can be made of plywood, MDF, or another flat material. The guide is 1/4-in. thick, and is shown as one piece in the drawing, but it would probably be better as three pieces with the head stop separate. These pieces would be sacrificial, and could be screwed to the base once they have been aligned in the jig. The part that I call “the receiver fence” should be cut to accommodate the height of the casing under the template base.
The template base is screwed to the receiver fence, and the templates fit into the base recess. The recess would be milled to allow the template to sit just proud of the base so there will be nothing to bump the router. You will notice the corner radius is different on the top and the bottom, so the templates will only fit in one direction.
The casing legs are cut square and milled face up in the jig. The left leg is placed against the left guide, and the right leg against the right guide. The templates are flipped over to make the opposite hand-cuts. The first cut template will cut the dado on the miter and the rabbeted area. The second cut template will adjust the height of the pin that fits in the dado cut in the head piece. Of course, the second cut will require adjusting the plunge depth of the router. Keep in mind that the template is not in contact with the workpiece, so any wobble will affect the cut.
The head jig is a little more complicated, but only for the initial setup of each casing. The head piece should first be cut to size with the appropriate miters. It will be milled face down and centered in the jig. The head jig is made like the jig for the legs, with the following differences: The left and right guides should be adjustable, and the head stop cut with a 90 degree angle. The head stop should be placed with the point at the exact center of the jig. Once it is properly adjusted, the head stop should not have to be moved.
To cut the head piece, the molding is centered face down in the jig. A custom shim will have to be used for each casing profile in order to support the thinner side. The back side of the casing must be absolutely level with the jig.
Since the rabbeted area on the head piece will change when using moldings of different width, you will have to place the casing in the correct position for the first cut. The short point of the miter should be aligned with the template (1/16-in. from the template edge), so the shoulder of the rabbet is cut to this point. Measure the perpendicular distance from the head stop to the miter, and make a right-angle or chevron shaped spacer block to that dimension.
The spacer block is only used for the first cut. It is removed, and the work piece pushed against the head stop for the second cut, which will be the dado cut in the head piece. Again, the templates will flip to make the opposite hand cuts.
Different casing depth and width would dictate the four cutting depths on the router; however, once set on a plunge base this should not be a problem. If I were doing a lot of this work, I would probably make a setup block with those depths for future reference (or use multiple routers). The use of a plunge base would also allow you to step the first cut, which could be pretty deep, especially on the leg piece.
This is just my concept. I don’t believe that this joint would appear in a tract house, but possibly in a custom house with a lot of trim. I think the initial setup could be made in the shop, and the jigs would be compact enough to go to the job site. Of course, the operator would have to be sharp enough to select the right cutting depth, and to stop the head piece dado cut before it hit the face of the casing.
I’m sure you will all let me know what you think, and your comments will direct where it goes from here. Since I’m mostly retired, I don’t have a need for one of these, but I do enjoy making jigs and trying to solve the problems!
(Illustrations by Wm. Todd Murdock)
Svend immigrated from Denmark to California in June of 1958. During the latter part of a three-plus year stint in the army, he worked part-time for a general contractor in northern California. The job turned full-time after he completed his time in the service.
After moving to the Palm Springs area, he worked in several different trades, starting a Masonry and Concrete business with a partner in 1975. He obtained his general contractor’s license in 1979, and in 1980 changed the business model to pre-cast concrete, commercial, and industrial general contracting. When the partnership dissolved in 1995, Svend had an opportunity to build a high-end custom home for a friend. That job led to building more custom homes in the same country club, which lasted for twelve years, until his recent retirement.
Svend enjoys woodworking, metalworking, and all projects that involve creating something with his hands. He also enjoys a tennis game once or twice a week.
Very nice Svend. This is what I was talking about way back when the first article was published. Although I’m not sure if I didnt think about it enough, or perhaps you “overthought it” ;-)
Oh, and perhaps the “stop problem” on the head piece dadoe could be handled with a simple brass screw stop that we use on framing squares for laying out stringers and such?
Thanks Ben for your comments.
I’m not sure that I follow your thinking on the stop.
I went to the two tmplates beacuse of the experience I had with the prototype that I made. With three openings the 1/4″ melamine was getting a little flexible and since the cuts overlap there is no way to make a template that would work without having to move the work piece wich reflects on the accuracy.
I think you could use a loose tenon of a thin plywood, and then you would only need one template to do both the head and the leg.
Thanks for the comment Sternberg.
I’m not sure how that would work but I would like to see your sketches.
I think that Todd Murdock did a super wicked awesome job on those Sketchup illustrations and videos!
That’s exactly what I was thinking Gary..
Gary and Joe,
Thanks! I was inspired by Svend’s ingenuity.
Very nice job with the SketchUp drawings Todd!
I second that Gary, and thanks to you for the editing.
I’m sorry that I’m late on these replies, but I had a chance to get out of the heat this weekend. Left Thursday at 6 PM and it was 104 degrees, two hours later at the beach it was 64 degrees, nice change.
I would stop the mortise and tenon shy of the edge. Your joint would then not slide together, but snap together with enough “slide” to allow the joint to pull tight.
An epoxy adhesive would allow this to be used onsite, and the joint cut, assembled and stuck on the wall in a matter of minutes. Epoxy or some similar non waterbased, adhesive would also prevent the tenon from swelling and telegraphing into the head casing.
The tenon could also be made of aluminum to provide a positive location of the joint, which would have more than adequate glue surface, without the tenon being part of the glue joint.
Thanks again Sternberg, as I said I would love to see your sketches.
As it is the joint needs no glue, it snaps together and can be carried to the site an attached as usual.
The hardest part is getting the templates cut, which would be best handled by CNC for perfect edges and proportions. Get a CNC outfit to cut the template sets and we can build the jigs to our needs. Sell the sets and we will buy them as this appears to be a valid lost technique for miters – inside or out.
Thank you for your comment John.
If there is enough interest I can certainly can explore this further, I will have to hook up with someone who has a CNC router and find out what a test cut would run.
Nice article Svend! Can’t wait to try it out.
And those videos are SWA Todd!
Thank you Dave,
Does that mean that you would be interested in a jig?
Great drawings and video with lots of time spent on configuring the model,Thank you for your time.
Todd did a great job with the few things I sent him.
Svend, amazing article. I had to read it twice just absorb all the info. I’m with Gary, the SketchUp drawings really help show your descriptions. Don’t know if I’ll ever try this but I am certainly intrigued. Well done.
Thank you Matt,
I agree, Todd’s work was over the top on this article. I don’t know if this joint will ever be used in the field, but it is possible. I just started drawings on a router/mill CNC machine which I’m planning to build, maybe I will make the template setup a test to see what kind of accuracy I can achive on the unit, but it will be a while before that is done.