I am building a curved freestanding staircase on-site. The treads will have returns on both sides. What do you think is the best way to rout the tread returns? I've built curved stairs with no side returns before, but this is my first time doing returns on curved radii. I think I would prefer mitered returns because the grain makes the tread look more professional, but I don't know what the best tool and/or method for the job is.
(Architectural Woodworking Forum)
From contributor H:
We cut them with a band saw or by hand. Round them over and sand the tread after they are attached. This has worked for us for many years.
My other thought for bullnosing the tread itself was a long radial arm attached to a router with a pivot at the center of the radius of my curved stair. That would help me cut a near perfect radius on a tread template or each one of the treads themselves. If I went the template way, I would use the template as a guide to cut and rout the rest of the treads.
A steady hand on the band saw or shaper with template and bearing will work. I personally do not like the shaper method because it leaves the inside on the mitre return round. Too production-like for me. Perhaps someone near you with a CNC could cut them quicker and more precisely, but that would add costs.
I have always viewed curved stairs as a job that takes time. Much of it still is done the old fashioned way... by hand. Curved returns on treads is one of them.
Flip tread over (top side up), match up miter in return material to miter in tread, leaving daylight between miters (about a playing card). This is because after you cut, the return is going in a kerf width distance. Clamp return stock to tread (I use those small vise-grip pincher clamps). Flip back over to bottom up (where your pencil lines are). Cut along curved line with a jig saw, from rear tread to miter, cutting both pieces at same time. I didn't mention it, but after fitting return material, cut it to be 1 1/4" longer than tread width, and you either need to draw continuing curved line on return overhang, or eyeball it (I eyeball it). I use Bosch 101B blades (I think), as they are coarse, not much set, and are thick and hardly flex. Return should fit right in like a glove and be 1 1/4" longer than tread width.
Temporarily lay tread where it belongs, hold return to it and scribe a line 1 1/4" out along skirtboard (I have a 2" piece of 1" square wood that, when I tape a short pencil to it, gives me a 1 1/4" offset, for scribing). Then either using a small band saw or jig saw cut to line, you should have a proper return, 1 1/4" wide and 1 1/4" longer than tread width, and curved to stairs.
Put glue on tread end and return (I use TB II), pre-drill and install 2 #6 or 8 finish nails in return (hand drives). Put one nail in just rear or miter and second about 1 1/2" farther back (still allows tread to move). It is important to center nails on thickness of material, and sink deep, as you still have to route. Fill nail holes, in about 5 minutes wipe off any glue squeeze, and sand joint (sanding dust will fill any not-perfect fit, but it should fit right). And of course sand smooth the side of return.
I do a few ahead to give glue time to set, then route a 1/2" radius around tread and return (generally do some climb routing about the miter area to keep from blowouts). If all went well, tread should fit right in there with pin fit along sides where return goes past riser. After a couple for practice, they should be right on. Curved returns are more time consuming (hope you allowed money for this), but after a couple you get into a groove and it moves faster.
I am about to start the project and I am all for figuring out new methods, especially with these kinds of projects. I'll keep you posted on how it goes. I think I have to improve my jig and band sawing skills for this one.