Circle Doo-Wahs

How to mold large circular frames, commonly known as "Tondos". Actually, the paintings are Tondos, so the frames would be Tondo frames. On the end is a wooden block, adjustable and lockable with thumbscrews. On the bottom of the block, a 3/16" brass pin, which is inserted into a hole in a block at the center of the frame. The router is a Porter-Cable, with a plunge router base. The rods are 5/16" steel, lockable to the base with thumbscrews. At the left of the base, there is a brass "flange" I added to provide additional support for the rods.

 

Here, a frame in process. At the upper right, the block at the center of the frame. This is the one tool in my studio that does not have some sort of dust collection system. So, noisy, and messy. While I'm typing this, the idle part of my brain is thinking of how I can add dust collection, and the power cord all coming down from on high. Hmmm.

There is a "scary" aspect to using a router on a 50-60 inch diameter frame, mostly to do with keeping the noisy little beast stable. Now I'm thinking of how to add circular capability to my shaper, and power feeder. Hmmm, again.

The floor in the top photo, shows the detritus of gesso, and various sealers, toners and paints, from when the frame was too big for the spray area, where I generally make my messes.

 

Here is a shot of the build-up of gesso, sealer, toner and what not on the turntable in the spray area. It probably weighs twice what it did when I built it. I included, as a client was fascinated by the abstract quality of the accretions.

More design

Cutting out the outside of the frame (see previous post) on a jig saw.

And, starting to carve.

Design Evolution

I'm working on a small frame, with a somewhat "Art Nouveau" feel to it. I did some preliminary sketches, on paper, but shown above, I'm drawing with charcoal on what will eventually, be the frame. I have purposely not tried for complete symmetry; but just drawing both sides, rather than taking a tracing, flipping and transferring it.

Here, I'm approaching what the final design will be, though refinement of details will happen during the carving phase. The frame is butt joined using floating mortise and tenon (biscuits) construction.

Cutting circles

Above, my jig for cutting circles on the bandsaw. That is a 3 inch diameter circle being cut, and I've used it to cut octagons into circles for "tondo" frames, of 50 some inches in diameter.

Above, showing the the brass plates that slide under the fence, holding the jig in place. The two bolts act as adjustable stops, depending on blade size and position.

This image shows the bottom of the jig. The strip that rides in the miter slot of the saw, and the thumb screws that hold the sliding piece that adjusts for the size of circle desired.

Here, the jig is lined up with the blade of the saw, and the brass pin that the stock is centered on is visible. A hole is drilled in the bottom of the stock, as in the top photo, or, in the case of a tondo, a cross piece is screwed to the frame, and a block the same size as the frame is added for the machining operations, see below. The sliding element is positioned with the pin at half the diameter needed, stock affixed, then the jig is slid into the moving blade, and against the stops. Once stopped, the stock is turned into the blade.

Above, a tondo in process. The same pin hole is used to rough cut the tondo on the band saw, as well as a guide for a router.