How do I create a round profile to fit the tenon of my rail to my round leg?
Hello everyone,
Small introduction: I am a starting furniture maker from the Netherlands, so pardon me if I get some of the words and terms wrong. We use a lot of different words for parts and terms here. Plus, the metric system.
I was wondering if someone could help me with my problem. I want to create a rail with a tenon that connects the mortise on my round leg of a stool I am making. In my first design I made a countersunk square to fit the rail in the leg, so it fitted smoothly. But now I want to try and make it the other way around, so that the rail connects nicely on the legs of the stool. I’ve uploaded some sketches I made for an example. ( I don’t know the English term for such a connection).
I prefer to use machinery and powertools. So if anyone has any helpfull tips, links or suggestions how to achieve my idea, I will be ever so greatful. I have a hard time imagining how to do it, with handtools or machinery, so even the smallest hints will help me connect the dots and understand how to make this joinery.
Thank you all.
Max
Replies
Your first approach (make an apron-end sized mortise to take the apron end, inside of which is the second mortise to take the tenon on the end of the apron ...... this is not just easier to make but stronger. Housed and tenoned rails are a feature of Greene & Greene chairs, for example.
It takes precision, though.
But if you want to make the apron end rounded to meet the round leg, then you may have to use a loose tenon rather than an a tenon integral with the apron. You can then more easily get at the apron end to round it exactly to match the leg before making a standard mortise in both the apron end and the leg into which to fit a loose tenon.
If you can find a forstner bit large enough to drill the end of the apron to give it a radius equal to that of the round leg where the two fit together, that will work. You'd need a big forstner bit (expensive!) as well as a means to hold the apron (and the forstner bit) very tightly so that there's no vibration when bit meets wood.
Lataxe
Thank you for your help. I think I will indeed use a loose tenon instead of a regular tenon. And I guess I am going to search for that right fostner bit and just try it out!
If you have a router table a core box bit in a matching diameter to the leg would be another option. I don't know what sources you have MLCS sells these bits in up to 2" Dia I have no idea what that is in mm.
I would add that cutting the mortises before cutting the curves is usually a good idea and simplifies the process.
Hello, Max.
I thought about how I might approach this problem, and this is what I would try:
First, I start with the mortise in the round leg. For this, I would create a simple half-circle jig to hold the leg while drilling out the bulk of the mortise, or for stabilizing the leg for a mortising machine. The jig would be made by cutting a hole through a 3/4” board. The diameter of the hole would match or very slightly exceed the diameter of the stool leg. I would then rip/crosscut the board around the hole, leaving about 1” between the closest point of the edges and the rim of the hole. Then I would rip straight across the board with the hole, right through the center, creating two half-circle cups, with a flat underside, that could be used singly or together to hold the leg while the mortise is cut. (These jig parts might require being fixed to a base underneath to further steady things for the mortising operations.)
For the rail, I would begin by leaving the end of the rail square to the side, and the rail equal in length (or a bit longer) than the distance of the final exposed length of rail from the point on one long side (this side being essentially tangent to the leg when done) to the same point on the other end. (I’m assuming both ends will be joined to legs in the same way.) I would then cut a mortise of the same dimensions as what I cut in the leg, exactly in the center of the end of the rail. Finally, I would use a band saw to cut the curved end on the rail.
For the final joint, a slip tenon becomes the final piece of the puzzle. A carefully sized slip tenon made to fit the mortises of the pieces to be joined should allow one to glue, assemble, clamp, and enjoy.
I look forward to seeing what suggestions others will offer. I’m sure people with more knowledge and experience than I have will come up with better or improved methods, though I think my plan would work.
In the end, I hope you find a suitable answer, and that your work comes together well.
Best regards,
Perry
Thank you Perry for your great answer! I think I am going to stick to your idea for the slip tenon/loose tenon. I've got a lot more information to work from right now, and it helped a lot!
Hi Max -- others will chime in but there are three parts to the joint. First, rout mortises in the rounded leg. Attached are pics that show a jig for doing so. Second, you will need slip tenons with rounded edges. Third, you will need to rout mortises in the ends of the rails and then cut the end grain curve to match the leg radius. This last part is not easily done -- maybe a very large fostner bit? Hope this all helps.
An edit here on the sequence: Rout the mortises into the end grain of the rails first. Then figure out how to shape the end grain curve (large fostner bit on a drill press, or bandsaw then spindle sander?). Make slip tenons to fit the rail mortise and turn the legs to fit the end grain rail curve. Lastly, rout the leg mortises to fit the slip tenons. I would consider several practice runs on scrap before you try with your good lumber.
Thank you for this idea. I love the examples and the jig for routing the mortise in the leg!
Short of going full CNC, a custom shaper cutter could handle the cheeks and rounded undercuts, like running the rails for a rail & stile door on a router table. You would have to trim to form the shoulders, probably by hand.
I think cutting the flat into the leg is both smarter and easier.
Thank you for your idea!
My approach would be more conventional joinery. I would cut the leg oversized and milled square. Create the mortise and tenon in a conventional manner with flat surfaces. After the mortise and tenon are completed shape the leg round to your liking leaving the area where the mortise and tenon meet flat. It will take care to shape the leg but I think this would work if you take your time. Mark the edge where the rail meets the leg so you can
leave the surface flat. You can use a plane, spoke shave etc. Your issue is why chairs made in the Appalachian style use a dowel approach. You could also consider changing your design a bit to make life a little easier.
Create a wooden sanding jig same shape diameter as the leg...apply dst with sandpaper atop...sacrificial wood clamped against the long edge of your rail...spindle sand the shape onto the long edge of the rail...( or do by hand? should work for tapered leg or inconsistent radius as well ) )scribe those curves back the tenon length on the rail...cut your lines and carefully do the carve-out by hand keeping the overall curve slightly under radius to ensure tight fit....You can perhaps speed the procedure of wood removal with power tool(s) but this can be completed by hand fast enough....And if you can understand that, you have a Phd in mind reading ! :-) Small edit here...There might be the potential for end grain 'snap off ' where the curved tenon shoulders meet the leg...That's a different issue to address however good luck with it !
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