How might I make a wood frame for a round "Window"

charlessenf

Charles
Senior User
There are so many interesting glass plates in the ReStores. Some almost 'as clear as glass,' others so heavily patterned as to render them serviceable for illuminating an outhouse (or similar functional facility within doors) with the 'trick' (for me) being How to cut and mold and splice together six or eight (or twelve or sixteen) straight pieces of wood into a frame that would accept such a round plate of glass and prove sufficiently weatherproof to allow some measure of confidence when mounting in my shed (or outhouse) walls.

I cut some pattern pieces out of 1/8 x 3.5" scrap (I think it took six pieces to form a shape from which I could possibly rout a channel to hold an eight-inch diameter plate) only to realize that joining the pieces would be the challenge.

However, before that question, I still needed some help determining how to define the length of each piece needed to provide a (beefy - suitable or framing and exterior window) frame for a round piece of glass plate with a diameter equal to X.

I am thinking Mortise and Tenon joinery might be the most appropriate approach - and one I have the tools to form - but calculating the size of each blank section has me frustrated once again.

My thought was that, if the frame were (nominally) two inches thick, it would be relatively easy to round the in side with a band saw and finish the necessary lip with a router - possibly using the cutoffs from the band sawing to serve as a retainer to hold the glass (though any better idea/suggestion would be appreciated).

Then the beefy assembly might be rather easily amenable to incorporation into the wooden building of choice.

So, How many pieces of (2 by) material should I use to create the frame?
Assuming a 1/2" tenon on one end and the reciprocal mortice on the other*, how long need each blank be to mount a circle of glass X" in diameter?
At what angle must the blanks be cut?
And to what length?

Is there, perhaps a web page out there explaining this process - or a YouTube video or a phrase I might best employ to search for such guidance? (That is - what do I call what I am trying to do?)

Thanks for reading

* Again, this was my first thought for the joinery - but, forgive me as I know not and am willing to follow experience and practice rather than reinventing the wheel.
 

Roy G

Roy
Senior User
Charles, it would be easy enough to draw up the window on a piece of cardboard and then measure how long and wide the pieces of wood would need to be to form your frame. It would be easier to build the frame using two layers of wood, with joints being offset from the pieces in the other layer. I think this is common when you are making an arch . Once you're glued up a router could cut the inside and outside circles and you could put the glass in with glazing points and caulk, like a regular window pane.

Roy G
 

tvrgeek

Scott
User
I cheated when I needed a half-round. Had a mill just NE of here make one. It was surprisingly inexpensive.
 

charlessenf

Charles
Senior User
Charles, it would be easy enough to draw up the window on a piece of cardboard and then measure how long and wide the pieces of wood would need to be to form your frame. It would be easier to build the frame using two layers of wood, with joints being offset from the pieces in the other layer. I think this is common when you are making an arch . Once you're glued up a router could cut the inside and outside circles and you could put the glass in with glazing points and caulk, like a regular window pane.

Roy G
Ah ". . . making an arch . . ." there's a key word or a Google Search! Thanks

". . . joints being offset from the pieces in the other layer . . ." I need to work on this approach. I think it requires joining the "SEGMENTS*" with differently than I'd first thought.
30DegreeCuts.jpg

Then, (I suppose) joining the next layer end to end and so forth. Have not tried it yet.

* Segments - another Key Word - apparently, turners do it regularly. One thing (Arches) leads to another (Segments) and down the rabbit hole go I again.
 

Oka

Board of Directors, Vice President
Casey
Staff member
Corporate Member
If paint grade -the simplest way is imho is with 5/4 2x6 (or 8) sandwiched flat between two pieces of 1-1/8 ply (7/4/1 subfloor ply) glue and screw. Then cut the window in and paint out, then set the glass and trimout. I normally use a PVC material but you can use clear wood and use a conduit heat bender to bend the wood enough to make it round. That is how we have done it in the past when a client has a after the completion idea. "Hey I decided instead I want a round window here". The advantage is you end up with a very robust assembly that makes attaching everything to it easy.
 

charlessenf

Charles
Senior User
If paint grade -the simplest way is imho is with 5/4 2x6 (or 8) sandwiched flat between two pieces of 1-1/8 ply (7/4/1 subfloor ply) glue and screw. Then cut the window in and paint out, then set the glass and trim out. I normally use a PVC material but you can use clear wood and use a conduit heat bender to bend the wood enough to make it round. That is how we have done it in the past when a client has a after the completion idea. "Hey I decided instead I want a round window here". The advantage is you end up with a very robust assembly that makes attaching everything to it easy.
". . . I normally use a PVC material . . . " Another great idea! Thanks

Hmmm, PVC like those trim boards I got with a Cull Lumber bundle last month. Do you use PVC Plumbing Pipe Glue (and primer)?

Is "5/4 2x6" what they sell as DECKING Boards?

No idea what 7/4/1 Subfloor ply is or where one would buy it - but, I can imagine it comes in 32 SF sheets and is priced accordingly.

I bought a seven-inch diameter glass plate/serving dish thing and thought to build it into a shed to (got to love the alliteration) shed some light inside. Looking for an inexpensive way to use scraps creatively - if the concept catches on, we can go into production mode down the line - get a CNC machine!
 

Oka

Board of Directors, Vice President
Casey
Staff member
Corporate Member
Not sure if it is common in NC but it used to be a standard for beam floor systems , you could frame 32" o.c. and use it as the subfloor because it was rigid enough to meet code.
There used to be a a system that used this ply for concrete forming.
You can take a 2x6 and rip it down to 1-1/4, make it a little fat and then just run through a planer. I would only recommend doing this kind of cut with a Skil saw worm drive not a sidewinder as the sidewinder's balance it to wide .... unless you jig it up to provide wider support. Here is a simple jig you can make on the fly, or two. does not have to be close tolerance design just needs to work.
 

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Scott H

Scott
User
I remember seeing a video about making round window, I don't know if this is at all like what you have in mind.

 

charlessenf

Charles
Senior User
What is the OD of these pieces of glass? Maybe I missed that.
"I bought a seven-inch diameter glass plate/serving dish thing and thought to build it into a shed to (got to love the alliteration) shed some light inside."

In the initial post I just mention a glass plate as the diameter didn't seem critical and I knew I was talking breakfast/lunch/dinner plate (but did not specify that either).

In response to a reply from someone who clearly thought I was talking about making a 'real window' out of 2x6' and 1.25" thick sub-flooring, I offered the detail in quotes, above. My apologies for not spelling it all out in the first go.
 

JNCarr

Joe
User
I build a good number of clocks with segmented rings as the outer trim piece. Here are two of them as examples. The RHIT clock is 42" diameter and the State seal is about 14". The same technique works for any size.
I'd suggest a simple lap joint using six segments. The simplest way to determine the length vs width is as Roy pointed out - essentially by trial and error, given the width of the stock you have (there is of course a minimum width for six sides given the radius of of your glass). I use a more rigorous way as given by: Regular Hexagon -- from Wolfram MathWorld. Allow for about an inch or so undersize and over size from the final width you want for the ring the incircle and circumscribed circle. Cut both the length and lap at 60 deg angles. to be safe make a little oversize and be sure to use a jig to get all the pieces identical. Once glued up as a hexagon, rough cut on a bandsaw then use an mdf template and router to clean up. You can also do a round over (state seal clock) or ogee or??? to finish it off.
 

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charlessenf

Charles
Senior User
I build a good number of clocks . The RHIT clock is 42" diameter and the State seal is about 14".
I'd suggest a simple lap joint using six segments.

Thanks for the response.
"I build a good number of clocks "
I'd say you build a number of good clocks!


How would these work for the RHIT Clock?:
Units 8
Outer Radius 24"
Outer Diameter 48"
Outer Circumference 150~25/32"
Inner Radius 16~3/16"
Inner Diameter 32~11/32"
Inner Circumference 101~5/8"
Unit Length Outside 18~3/8"
Unit Length Inside 13~13/32"
Joint Width 0

CALCULATOR: Circular Paving and Fire Pit Calculator with Full Scale Templates - Inch

Calculator-A.jpg

Then I found this calculator: Woodwork Segmented Turning Calculator with Full Scale Printable Templates - Inch

So, these provide the length of each segment - but the calculator assumes butt joints. While I have a Biscuit Jointer and Pocket Hole thing and even an old doweling jig, I prefer the idea of overlapping joints and even making two such assemblies and sandwiching them together (possibly with a sheet of Birch Ply between (as suggested above).

If my calculations call for six six-inch segments butted together, would I cut them to six inches PLUS the depth of the lap? That is, if I want to rout or cut a half-inch long lap one half the depth of my stock on alternate faces of each segment, do I add that half-inch depth to the indicated segment length e.g. make the segments 6.5" long?
 

JNCarr

Joe
User
What you need to make sure of is the definitions of inner and outer radii (and resulting diameters) for the calculator. Is it inscribed radii or circumscribed? In other words does a circle touch the points or the sides? if it touches the points, the build-up wont be large enough. The picture on the right shows the distinction. As you can see the left image falls short.
Yes, you will add to one end. But if you add only 1/2" of length and cut that for a 1/2" overlap, your octagon will get slightly smaller. You need to add .5/cos(22.5) = .5412 =~ 17/32. I'd do 9/16". Just remember where the laps are you will get a bird's beak cavities on the inside and a double beak on the outside - the latter wont matter, but you have to make sure you size the stock to account for the inner one. Make the stock wider by the same amount as your overlap. The picture on the right shows exactly the .5412 addition, just to show it fits exactly the idealized segments in the center. In practice, as mentioned, I'd do 9/16 and the ring would be slightly larger. You can see the bird's beaks.
Note that in all of these, the outer dimension is too small to provide tolerance for routing - I just did it that way to stick with the inscribed/circumscribed discussion. Hope this helps.
 

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JNCarr

Joe
User
I just had the chance to look at the Segmented turning calculator you referenced. It works like a champ and it's very clear. I think you have all you need right there for the basic size, including inner and outer margins. With the addition of adding the lap joint overlap, you're all set.
 

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