A Circular Window Frame

by Michael Fitterling

hole in the wall

I just finished maple kitchen cabinets for my brother and sister-in-law's new house. They had an odd, little round window looking down from their daughter's room into the living room below. The builder just drywalled up to the edge of it, but they wanted something that looked a little bit more finished and which would match their maple cabinets, floors, and fireplace mantle. The cabinets were all made from hard maple, so that is what I used here. Here is the opening they wanted trimmed out on the bedroom side. If you look really closely you can just see the living room fireplace mantle though the window.

high up on the wall

And here is the other side, way up the wall, above the entry stair.

I started by kerfing a strip of maple on the radial arm saw, almost though the thickness of the board, just leaving about 332" or so of material on one side. This piece matched in width the depth of the hole from the surface of the wall to the face of the glass—about 238 inches. Next I cut a circle out of a scrap piece of plywood the diameter of the opening. I used some shims to hold the kerf open to ensure the circle was true. I figured the diameter of that opening minus two times the thickness of the piece of wood (58" x 2 = 1¼") then multiplied that by π and cut the kerfed strip that length. I then bent the strip carefully and worked it into the plywood form. That took a couple tries on the second window—the first attempt on that one split at the last moment.

curved kerfed strip

Here is the kerfed piece in the form.

I used some epoxy at the seam and clamped it so it would not spring out there, making a less than round circle. The epoxy is just a little insurance until the face can be glued on, because the face to ring joint will be a long grain to long grain glue-up and take care of ensuring the circle stays a circle once out of the form.

frame felloes

I next cut the face in four sections on the bandsaw. Here they are in their rough form.

too large biscuit slots

I was going to biscuit join the ends of the semi-circles, but alas the smallest biscuits I had were too big and the slot extended past the edge of the wood.

face glued to ring

This required a change of plans, and I ended up using dowels to join the sections. Next I glued the faces to the ring using yellow glue. I did not have to be exact here as long as a little of the face extended past the inside edge of the ring all around. Here the face is glued onto the ring, which is still in the form.

alternate use of lumber stack

I had to improvise to clamp the pieces together while still in the form. Here the window frame is clamped under a load of lumber. This made the clamping much more even and easier than using a bunch of clamps though the limited space in the middle of the circle.

evening the frame diameter

After the glue had set I simply used a straight pattern bit in a router to make the inside of the frame match the inner surface of the ring. Now the face had a round inner circle, so I set a compass so slightly narrower than the narrowest width of the face and drew a circle referencing off the inside of the circle.

sanding to the line

I then went to the combo sander and sanded carefully to the line around the rim of the window frame face.

front of the frame

Here is the first window frame, seen from the front…

back of the frame

…and the back.

puttying up the kerf with epoxy

I repeated the process for the second frame. On the second attempt to get the kerfed piece into the form, it wanted to break at one place. So I clamped the kerfed ring at the weak place against the form and mixed up some epoxy and maple dust to form a putty and forced it into the kerfs in that area. Once set, that kept the ring from popping out of shape.

chamfered by hand

I used a block plane and scraper to make a small chamfer on the outside and inside of the face to finish up.

finished frame installed

And finally, here is the window frame in place in the bedroom window. They will use just a little caulk around the flange to hold it in position, so they won't have to tear it up if the window ever gets broken and needs replacing. The seam on each will be positioned so it is not very visible from that particular viewing angle. The one way up the wall will have the seam of the inner ring at the bottom and the one inside the room will have the seam at the top because the window is pretty low on the wall there and, unless you lay on the floor, you will not see the seam.

. . . Michael Fitterling

© 2005 by Michael Fitterling. All rights reserved.
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