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A "MODERN" STAIR SWEEP
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"Here you go," Dick said handing me the ancient stair part. "I need this to be left-hand." I've always enjoyed working for Dick, a contractor who specializes in custom homes in the upper price range. He always gives me unique and interesting jobs -- jobs other trim carpenters/woodworkers are too smart to take.
So I had a 100-year-old right-hand stair sweep, hand rail and newel post salvaged from some long forgotten mansion. The homeowners had been collecting miscellaneous salvaged house parts for more than five years. It was my job to make them fit into the house Dick was building.
At first glance, it seemed to be a pretty straight forward project. Calculate the radius of the sweep in the plan view from the hand rail to the newel cap, apply the pitch of the hand rail, cut everything out of a laminated blank and, presto, a perfect fit! Mmm… Better make a mock up.
I've learned two things doing projects like this: Full-size drawings save time, aggravation and mistakes; mock-ups save material.
So I made the full-sized drawing from my site measurements. I glued up some scrap plywood for the blank, cut out the plank and rough-shaped the new sweep. I could not wait for tomorrow to test-fit the new sweep. "Dick will be so impressed I got this done so fast!" I thought.
Tomorrow came, and I did the test fit. Not only did the new sweep not fit, it wasn't even close! "Silly me, I forgot to subtract that one measurement from that another. This will be easy to fix," I said to myself.
I was tempted to just go ahead and make the final piece, but decided another prototype would be in order. The second one was much better than the first, but not ... quite ... right. "Now what?"
The more I looked at the original sweep, the more it did not look like a modern radius sweep. I needed help.
A search through the public library database was not much help, so I started to browse the stacks of books. Finally, I came across "Modern Carpentry Techniques." Inside I found a chapter on stairs with nice diagrams and black-and-white photos of nearly the exact stair I was working on!
Now the only problem was the pages, and pages, of algebra and trigonometry formulas explaining how to build such a beautiful stair! "Well, maybe I can figure this out ... at least there are pictures," I said to myself on the way the checkout.
The math had me stumped after the second page. However the photos and diagrams were of great help. I soon realized that my sweep was not based on a radius, a part of a cylinder, but rather an ellipse, which has a constantly changing radius! That is why mine looked so different from modern sweeps.
BACK TO THE DRAWING BOARD
Armed with this new-found concept, I started to redraw the earlier plan view. I knew the position of the hand rail and where the newel post had to be positioned. I decided to assembly a mock-up of the stair upon the drawing to get a true representation of the pitch of the hand rail. I made a block of wood to represent the outside dimensions of the handrail. I built a plywood ramp and positioned the hand rail block at the exact position in relation to the center of the newel post. The newel post had a cap that was attached to the sweep and the newel post. A finiale was tacked to the cap to hide the fasteners and finish the post.
Mouseover graphics for cut line.
I used a piece of scrap wood to represent the end of the sweep and cut a piece of plywood to represent the bird's mouth to be cut into the cap. With these positions defined, I glued eighth-inch square balsa wood at each of the four corners of the blocks. This defined the horizontal and vertical shape of the needed sweep.
Now the challenge was to transfer the shape as defined by the balsa wood "corners" to the piece of walnut from which the new sweep would be carved. This was done with paper tracings and direct measurements. It was at this point that I realized my 30-year subscription to Wooden Boat magazine was starting to payoff!
With the walnut scribed with plan and elevation lines, it was a simple matter to cut it out on the bandsaw. I did not cut out the bottom, wanting it for support as I carved to the final shape.
Carving was a great relief after the trials of the layout. I did have to invest in two new tools, a compound radius plane and a spoon plane (oh darn!). I also made scrapers to match the profiles of the different sections of the hand rail. This work went surprisingly quick and was most enjoyable.
The last stage was to cut the bottom off the sweep, which was a bit of a challenge since you need cut in two planes at once, so I cut wide then worked down to the line with hand tools. A final sanding, cutting the point for the bird's mouth, and it was done.
Installation went smoothly; everything fit as planned. Sometimes, I just get lucky!
Oh yes, that book "Modern Carpentry Techniques" -- it was first published in 1902!
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