How to make a round window frame?

[roger wiegand]

One of the last projects I need to do to complete the interior trim on our house is to build a frame for and trim out a round (interior) window. The window came from an 1830 building at Harvard and was rescued from a dumpster by our architect 30 years ago. I've rebuilt and re-glazed the window itself, which will end up painted.

Now I need to make a frame for it. All of our interior woodwork is cherry. I've thought basically that I need to make a round piece that fits into the octagonal hole in the wall, coming out to the wall surface on each side then set the window inside of that with appropriate curved moldings. The frame on top of that can be simply applied to the wall. I've attached a picture of my current design concept, as well as a picture that puts the window more in context and shows what the other woodwork looks like.

I'm not sure of the best way to build the round frame. My first thought was bent lamination, and I've already cut and prepped thin cherry plies that will bend into that size circle. How to keep everything lined up and then pulled tight then? Again my first thought was a full size interior circular form made out of particle board or such where I could wrap the plies around and secure them with a band clamp. Past experience with this method is less than encouraging i terms of not having any gaps and getting perfect contact all the way around for 4-5 plies. Would a vacuum bag be easier? Should I try to do it all at once, or just add one play at a time, independent of holding method. The edges will be visible at the reveal so have to be both cherry and decent looking.

Is there an easier/better way to go about this that I've overlooked?

I thought about doing an enormous segmented turning, but I'm not sure all the joints would look good. It would be fun to try turning something 3 ft in diameter.

Bending ply might be easier to form into the right shape, but then it would need to be veneered on the inside of the circle and edges, which also seems challenging.

Thoughts or directions to a reference on how it's done by folks who know what they're doing would be appreciated.

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First picture is the window, second the hole, third the hole from a distance, and fourth, the intended window design. The triangular areas will be birdseye maple like on the other windows, with the rest of elemts cherry, differentiated by using different thickness of wood to create reveal line.

[Darcy Warner]

I would do a segmented glue up with 8/4 cherry, bandsaw close on outside, maybe even cut through and do inside and then use my shaper with a template.

[Walter Plummer]

I think the segmented method would be the most reliable and probably the easiest. I don't think the joints would be a problem as long as the color is consistent.

[Jim Becker]

What Darcy said--segmented glue-up--and if no shaper, do an alternative milling method by using a trammel and multiple cutters in a beefy router to gradually form the profile. Or do the glue-up and have someone with a CNC cut it for you. :)

[roger wiegand]

I'm having trouble thinking about using a shaper-- we're talking about a hoop that's 5-1/2" tall and three feet in diameter. The tallest cutters I have are only about 2". Would you use a 6" tall cutter? That sounds scary. Making a 40" faceplate and turning it outboard on the lathe seems more feasible. Or am I completely misunderstanding the suggestion?

[Kevin Jenness]

Laminate two half circles with a bending ply core and cherry face, using epoxy, a male form, and a vacuum bag outside the form. Strap clamps to pull the layup into shape, bleeder fabric inside the bag, the form more than a half circle. Trim the edges, then the legs and join the halves together with biscuits and strap clamps. Band the edges with segmented cherry and trim flush. Depending on the radius you may be able to use the same form for laminating the stops, or make a form to the inside of the stops and pad it out for the jambs. Do a test to see if adjustment for springback is necessary.

You could segment and bandsaw the jamb halves, but it will take a lot of material and sanding the female curve. Shaping a bricklaid blank will take a heavy shaper and tall tooling with potential for tearout on the uphill parts. Laminating works well for jobs like this of any width. You can pre-sand the faces and get a cleaner look than bricklaying. I like to use 1/8" bending poplar for the core. It takes less force than all solid plies.

[Darcy Warner]

If you use a template and bottom bearing pattern head, you can take small bites. Do half, flip over with template on other side.

I would turn it on my lathe too, more than one way to make chips.

[Bob Coates]

Segmented perhaps 48 segments to a ring. Also if the window is frame is 5 1/2 inches deep(tall) how about making multiple rings like you would for a bowl or vase and build to the 5 1/2 inches. Make a plywood, or mdf to support the router and shape each ring as you build. OR
If you can turn 3' go for it.

[Paul Girouard]

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I’m prolly not understanding a few things , the frame is square or a retrangle so IF this assembly where to be made ONLY the premeter of the round window , which I assume fits into the round center hole needs to be the depth of the wall the entire assembly fits into. The triangular areas would be mounted on GWB and or framing IF this where a regular square window opening.

So you’d have two interior grade rectangular frames , connected by the center round section that the spoked window fits into.

Is that understandable ???

You can buy pre-formed plywood cylinders , I’d attempt to find one with a inside diameter that closely matches the OSD of the spoked window.

That could be veneered , or possibly even be ordered with the Cherry veneer you decide. The cylinder could then become the form you start your lay up on.

This is a really cool project! Your window wall appears very well done, did you do that trim out as well?

[Mel Fulks]

I've always used the segments . But I've never used the shaper to trim them. I use the bandsaw to make a block that is
just a bit smaller radius than frame. Then use double face tape to stick block onto pad of belt sander.

[Kevin Jenness]

Paul makes a good point about premade plywood cylinders. Here are two sources (I have no experience with them) https://www.kellerwoodproducts.com/high_pressure_laminate_hpl_veneered_consoles.php https://www.roberts-plywood.com/full-circles.html. If they have a stock size with interior cherry veneer that works for your project it would save you a lot of time.

[roger wiegand]

Cool-- Keller offers cylinders that are large enough in diameter, and they aren't very far away. I'll give them a call in the morning.

Yes, I did all the interior trim and floors in our house. The rest of the windows were just flat and square, so no real issues in trimming them.

[Paul Girouard]

395960The round trim I’d segment and rout a MDF ring that matched the inside and outside diameter on the what I’d call round casing , once the thru wall round section is made the ring could be routed to flush up with of just slightly overlay the face of the plywood ring.




I’d lay up the segmented casing over sized then rout it to the round shape using the above routed MDF form.

The segment you could use pipe clamps as it would be a octagon at the glue up time.

[Paul Girouard]

Cool-- Keller offers cylinders that are large enough in diameter, and they aren't very far away. I'll give them a call in the morning.

Yes, I did all the interior trim and floors in our house. The rest of the windows were just flat and square, so no real issues in trimming them.


Really nice work!
Break this window into pieces in your head. Once the round part is made up the square parts sort of just jigsaw puzzle in and around the round center.

There’s a few different suppliers on the round cylinders , I don’t recall who I got the last rounds from for the last round relight window I did. I still have a left over about 7 or 8” wide IIRC , I could check the diameter on the piece I have , if it fits I can ship it to you.

[Steve Jenkins]

I’ve used the Keller Products cylinders quite a bit and would go that route. The cylinder is ply not mdf. I’d then resaw a single piece of cherry to veneer the inside and segments to cover the front edge. I’m assuming the outside face doesn’t need to be cherry.

[Chris Fournier]

I'd do a bent lamination personally. I have made many of these and they have served me well. I'd resaw a board, keep everything in sequence and go to town.

[Paul Girouard]

The round cylinder I have in my shop is 3/8” thick , ISM is 27 1/2” , it’s 8” deep.
I don’t think the 3/8” thickness would work for your project even IF by some miracle your spoked wheel window happens to be in the 27” round size.

Did you also make the piece of furinture that below the relight window project area?
Or did you trim the windows in a similar fashion and that piece influenced the window trim design?

[roger wiegand]

Hi Paul, the window is 35-1/2", so won't fit in a 27" hole, thanks for your kind offer.

The cabinet (one of a matching pair-- they were made to flank the fireplace in our last house) was made by Bill Laberge of Dorset VT. I had a more than full time job back then and my wife was tired of waiting for furniture. He did a spectacular job on them, I use them for inspiration to do better work. I've since made a number of similar pieces, but mine aren't yet as good as his.

We bought a run-down 1950 garrison colonial seven years ago and decided to do a deep energy retrofit and add an addition, re-doing the whole thing in a English Arts and Crafts inspired style. The new window is in the addition we built. All the window and door trim is in a very simple A&C design that I adapted. On the first floor it's all cherry, on the second it's painted poplar. The floors are birdseye maple with cherry and walnut picture frame borders and some inlay work.

DW and I have had a long term deal where I can buy whatever tools I need and can use first rate materials as long as I do all the labor on house projects. Our costs come out about the same as hiring the work out and I end up with tools and upgraded materials. The biggest win was that this house had a 36 ft square derelict barn that I rescued and turned into my woodworking shop-- I have an above ground shop for the first time in decades!

[roger wiegand]

I thing I'm going to have a go at the bent lamination. I've already done the prep work to make the plies, and I've always wanted to try vacuum bagging. A form will be pretty straightforward.

If that fails then I'll go the monster segmented construct.

[Paul Girouard]

Excellent on the shop and the deal you struck on the house and tools!
It’s interesting to mix the different woods , the Art and Craft / Craftsmen style is one my favorites.
Hopefully you’ll run a bit of a thread as you move forward with this project!

This was a mantle I did 20 years ago , Cherry , Maple and Copper elements.


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Along with a stairway:

[jack forsberg]

I've always used the segments . But I've never used the shaper to trim them. I use the bandsaw to make a block that is
just a bit smaller radius than frame. Then use double face tape to stick block onto pad of belt sander.


same here. too dangerous on a spindle moulder . I made a rub collar for the bobbin sander and can pattern sand to 9" tall and do thin section too with out fear of tear out or explosion of the part due to short grain .


https://www.youtube.com/watch?v=Qzhaa5MmnTE

[Warren Lake]

we did it on the shaper, it works well. First cutter was straight high speed steel trimming to the template size from rough bandsawn just oversize. Then the profile next, that's a small profile shown If its a big profile can take a few or more passes as the ball bearing width was good, likely an inch or more, you can do a pass then lower down and go in again and still be riding on the bearing.

My only gripe at that time would be a jig with only two handles is not good enough, I don't like the hand over hand thing as you have to chris cross your arms at some point. We weren't taught to pull the jig away to change hands and likely on purpose. If i was doing that again id make a mirror image template not handles and then you have a continuous thing to handle as you feed and its more comfortable. Stuff we did was in solid, no reversing was done running into grain and no problems. Your window is nice and fine. Joe likely has some miles of this stuff run and with newer cutters.

[roger wiegand]

Aha! An excuse to acquire a tool I've always wanted-- the spindle sander.

Note there is no "profile" on the problematic piece-- it is just a hoop, like a drum shell or banjo rim, only bigger, 1/2-3/4" thick, 5-1/2" tall, ~35-1/2" inside diameter. Square corners.

Hmmm-- there's a guy who makes pretty big bodhráns not far from here. I'll have to see how he does it.

[Joe Calhoon]

If I understand you need a jamb 3/4” or 1/2” thick X5 1/2” wide with only the inside face showing and possibly a little of the edge showing if your casing has a reveal.

lot of ways to do this but here is a quick and dirty for the jamb part.
For the jam I would use bender ply with veneer and backer on the inside face. You could use solid plys but they would have to be pretty thin at that radius. Make a form or use the window as a form and screw the bender to it to make the curve. Possibly do the veneer after the bender is glued and set.

Here are pictures of how we do jamb extensions on curve top windows. I used 2 layers of 1/8” solid for the inside. These are slight radius and 1/8 is fine. I use the same template that we shape the window heads with reduced by the jamb thickness. Glue and screw the bender and veneers to the rebate on the window frame and clamp the template to the outer edge. If it’s wider than 4 or 5” you need deep reach clamps and culls in the center. Doing a full circle complicates things a bit. I would offset the bender plys and dry fit around the form before gluing.

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The round casing or trim trim piece I would make in 6 or 8 segments for that size cut out of one board for grain match.
inside could be done on shaper with template or router on trammel or use a spindle sander. We have shaped a lot round 3” thick windows with no tear out but it’s advanced shaping for sure. For high precision jambs where springback can be a problem we brick lay out of solid and veneer the show side. I don’t think you need that precision for this project.

[Keith Mathewson]

A bent lamination works well for this project. Several pieces of angle iron and a backer board make a quick jig. The same method can be used for the casing, similar to what is shown for a curved stair tread. Be aware that the amount of spring back is based on the number of plys. Make the pieces 2/3 of circumference and trim to length. Spline and join casing. A single piece of veneer can be used for face veneer and joint located at the 6 o’clock position. Glue two additional plys orentared 90 degrees off of joint on outside of casing. These do not need to cover 100 % of surface area as they will not be seen. Casing joint is also orentated 90* to jamb joint

[Mel Fulks]

I've seen factory made and shop purchased circular jambs and casings that were laminated. So obviously some use them
but I would not use a laminated casing under any circumstances. Okay for frames, but even there my preference is
Italian bending ply or segment stacks.

[Joe Calhoon]

That Italian bending ply is nice stuff Mel. None of my suppliers here carry that. The bender ply we get is marginal.
I don’t care for laminated casings either but is the norm for the big window and door companies.

[roger wiegand]

Following up on this thread-- I made the round frame by bending three plies of cherry around a purpose-built form, than backed it with a piece of bending ply. My clamping wasn't prefect but good enough in the end. I also got to do some fun experimentation with different ways to cut circles.

Here are some pics of the work in progress and the final product.1) finished window in context, 2) gluing up segmented pieces for the round frame, 3) the cylinder and round frame, 4) laminating the cylinder, 5) the finished window, 6) router trammel setup for cutting a circular router template (I wish I knew how to get these to show up in more sensible order!)

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Thanks, for the help in thinking about this project. DW has just placed her order for four new nightstands and a couple end tables, so I'll be busy.