Bump-cut Band Saw Tenons

IMG_1439Because I had to make the columns on my tall clocks longer than needed so I could form the reeds with my scratch stock, each column needed to be cut to length. (The blue tape held together a fracture at the end of the column – I use this same technique when turning, if need be.) Once at length, each end of the columns needed to be reduced in diameter to fit into the brass capitals. Then ends of the individual reeds are then shaped further.

My first thought was to load a column at my lathe and turn the tenon before I cut the pieces to length. I want a snug fit through the capital, and there would be no way to check the fit while on the lathe – there was about 2″ to remove off each end of the columns, so I couldn’t simply slide on the capital. IMG_1440If I cut the lengths first, I lost the center markings and, for me, that makes loading the piece on the lathe too much of a hassle (I’ve not had success remarking the center whether using a center-marking gauge or not).

What I decided to do was to cut the columns to length, then use my band saw to form the tenons – it’s a similar operation as making a bump-cut tenon using a table saw. (You can see a short video of this technique here.) In the photo above right, you see the end of the columns after its been cut to length. (You can also see that there is more work to do on the reeds.) And below you can see my setup at the band saw.

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I used a bench hook to guide the stock, and used a spacer (set between the hook and band saw table) to locate the hook fence just beyond the blade. This setup is somewhat critical. If you’re too far beyond the blade, you will remove too much material. (If you’re in front of the blade, your tenon would be too fat.) I say that setup is somewhat critical because you do have a little adjustment. IMG_1445That comes from moving the band saw blade forward or back using the guide bearings on the saw. A simple tweak can push the blade forward to allow you to dial in the best cut. I went for a tenon that was just too snug to fit my capital so I could lightly sand the tenon to fit. The photo shows a closer view of the setup. (Click on the photo to see it even larger.)

I positioned the column tight to the second block – that piece has a 1/2″ notch which is the tenon length, and I’ve clamped it tight against the bench hook to make sure the two are aligned. With the column set against the second block, I spun the stock to cut the tenon shoulder. I then nibbled away the waste in one area of the tenon – it takes a bit of wiggle and movement. Once that area is flat and clean, I began the bump-cut technique. IMG_1446Back and forth into the second block while rotating the column; it’s like rubbing your head as  you pat your stomach.

When a full rotation is finished the tenon is formed. Two clocks, four columns per clock and two ends per column left me with 16 tenons to form. Taking the time to set up this method saved me time in the long run. And I didn’t waste a column that needed to be replaced with another – that would have burnt at least an hour of shop time.

Build Something Great,

Glen

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