Making a curved window frame help?

[travis howe]

Did some searching here on smc and not finding this exact project.

We have a window that is close to a half circle that is about 8feet across the bottom. It's a half circle all the way around except for about the last 4 or 5 inches go vertical down to the bottom.

Thinking about building a frame that would fit inside of it w/ stained glass. It would either be one big sheet or I would add some pillars inside of it to break it up a little.

I would like to have the frame about 3/4 in thick and 3 inches wide, how would one go about make the large bent piece, likely to be red oak or alder.

Thanks all.

r/t

[John Keeton]

Travis, first let me say I have never done this. But, I fear attempts to bend a piece of wood 3" wide would fail. I would think the best method would be to assemble together a series of roughed out sections, end to end, to approximate the arc. Then build a long trammel board to form the arc necessary to match your opening. You could then use a router mounted on the trammel board to cut the finish piece, and mold the profiles, if any.

Brief description, but perhaps someone else may have some pics or can guide you to other resources.

[travis howe]

Thanks John! I can begin to picture something now. I've never dealt with a trammel board (yet). Also wonder if I could do the same thing w/ the rough pieces, get them glued together and trace over the patter of the arc onto the board(s), get it as close as possible w/ the bandsaw and then hit it with the spindal sander? Maybe double side tape pieces to make a mirror copy so I have two pieces to put the glass into.

[Peter Quinn]

You can do a bent lamination, but the face grain will suffer over that width (3"). You might overcome this by using a veneer for the face over either a bent lamination or a brick laid plywood blank, possibly two layers of 1/2" baltic birch, overlapping the segments by 8" or more. I would probably assemble the curve from five segments joined with half laps or pegged bridle joints. If this is to fit into an existing window, i would either create a template using a router on a trammel as a pattern for the segmented blank, or cut it free hand and sand but leave a generous reveal between the jamb and the stained glass insert.

That is a pretty large piece of glass. I would consider increasing the thickness to 1 1/8" thickness, and possibly include some mullions and muntons to stiffen the frame a bit. Also, a 4X8 window insert is going to be quite heavy, so make sure to devise a scheme to raise it into place and hang it securely. Possibly a series of four smaller panels each representing 1/4 of the diameter desired would be more feasible and easier to handle? Possibly with a slight reveal between each panel?

[Steve Jenkins]

which dirction is the 3" is it like a face frame with the 3"" laying in the same plane as the window or is it like a jam with the 3" covering from the window to the wall face? If the former I would use wider pieces than 3" and glue up half an octagon then cut it into the half circle plus legs that you need. If the other I would make a bent lamination with the laminations about 1/8-3/16 thick.

[Ray Frederick]

I do these kind of frames all the time, here are a couple ideas to try out.

#1 - If there is solid wood blocking all the way around the window opening, you can kerf a piece of your red oak or alder that is 3/4" thick by 3" , kerf it to 3/16" so that when you apply your casing it hides all of the kerfs, you can then fill the kerfs with glue and nail/screw it into your solid blocking, your glass stops will cover these screws/nails. You will have to trial fit it to get the angled cuts at the end right where it transitions to solid, then just cut your regular vertical pieces with an angled top and pin nail those to the sides of your opening. You will need to get on the other side of the window and trace the opening and do a bent lamination for your stops, just put a piece of plywood on the opposite side of the opening(or figure out the radius and use a trammel) then make a form and bend the strips around, 1/2" by 3/4" is a good size for the stops for a 3" frame.

#2 Is a bent lamination for the entire arched portion of the frame, the variable on this is you can do a veneer face if necessary though I've made a lot of doors without my face grain suffering, as long as my bottom lamination piece is 3/16" my casing hides my other laminations on the edge.

Sorry if I was confusing at all, let me know if you have more questions.

[John Keeton]

Maybe double side tape pieces to make a mirror copy so I have two pieces to put the glass into.Travis, it is starting to sound like you were actually talking about the jamb of the window with stops, rather than the casement trim. In that case, I think Ray has the best solutions. My initial suggestions were intended for the casement trim, and I think Peter, Steve and I are talking about the same method of segmented casement using a trammel board or some other such method of getting the radius arc.

[george wilson]

The millwork shop at Col. Williamsburg years ago had to make a replacement window for the Toymaker's Shop in Merchant's Square. they laminated strips of wood. Somewhere they got a formula out of a book that determined how much overbend they would have to make in the bend to allow for springback in the given thickness and number of laminations they used. It seemed to work fine. I don't do that type of work,but I worked next door and saw the job progress.

[travis howe]

Sorry for the confusion....as well, I'm not familiar w/ all the terms of a window.;)

I've attached a picture of a similar window. The casing that holds the glass in on mine is some type of vinyl that is pretty much 1 1/2 by 1 thick. This is also where I would like to essentially mirror that shape in two pieces w/ the glass in the middle of the two. It would be attached to this current glass / casing as we can remove it easily if need be. It's up on our top peek of our home about 25 feet above ground.

I understand what Ray is describing w/ the kerf to bend it but not sure the casing portion applies to what I'm doing or I'm missing something?

Thanks all!

[travis howe]

pic below as discussed above.
tks

[Peter Quinn]

"...thinking about building a frame that would fit inside of it w/ stained glass..."

So when you say frame, I am thinking frame, like a very large window sash. Is this correct? Curved head, bottom rail, muntons, etc? Or are you looking to make some type of curved jamb lining to capture an independent stained glass unit, something leaded and framed on its own? I am a bit confused and I can't see the picture you referenced in your last post.

Edit: I can see the pic now, still confused as to your intentions?

[John Keeton]

Travis, the pic helped and I think Peter has correctly stated the term "sash." The sash would fit in a jamb, but in this case that appears to be integral with the wall. Casement trim would be applied to the wall, and overlap the jamb, but in this case there does not appear to be any casement trim.

If you are trying to build the sash, then I think you could do either the laminations or the segmented method. The laminations should be stronger, and given the weight of the window glass, a safer option. You could hold the glass in the sash with stops, also built as laminations. As you originally stated, breaking this up with mullions would certainly make it stronger.

[george wilson]

I thought you meant a curved bay window.