Tutorial: Making a Window Trim Ring

bobloblaw

Member
I've taken quite a lot from this forum, so I'm happy to finally have a chance to give back. A question myself and others have always asked, is how people cleanly and professionally trim out their windows or flares. I've never seen anyone provide any kind of real instruction, so I figured I'd take some pictures as I made one for myself.

Do note that this is only the method I devised to create the ring. It’s probably not the simplest or easiest... just what I reverse engineered from some Instagram photos and my knowledge of woodworking.

The overall idea is to use bending plywood to create a formed ring that will fit around the window and attach to the wall panel. This is done by creating and building up a template, and then scribing and trimming the ring created.

While I'm making a trim ring for a window here, the same technique can be used to make rings for flares, smaller windows, etc.


Step 1 - Make a template:

Buy some 1/4" thick plywood that is at least as big as your window. It doesn't need to be quality stuff, but you do need to be able to see a pencil line on it. Once you have it, cut it to a shape that’s roughly 1" larger than the window itself as it will be scribed to fit better.

I figured out this shape by putting some clear plastic sheeting over the window and tracing around the compression ring. Also mark where the opening knobs are as you'll cut out holes for those as well.

Transfer this shape to your plywood and cut it out. Cut out the holes to go around the window knobs as well. Test the plywood against the window and ensure that there is about .5-1" overhang on all sides. Once that’s good to go, get some thick double-sided tape (strong), or a few pieces of VHB and tape the template to the window. You'll now trace around the window.

To do this, I cut a tiny piece of pencil that is a little smaller than the height of the window's compression ring (about 1") and sharpened it with a very small point. This allows you to place the pencil behind the template and on the compression ring. Hopefully, there is just enough template overhanging so that you can reach your fingers behind it, hold the pencil, and trace around the ring. The benefit of using a pencil like this is additionally that it will end up creating a line that’s roughly 1/8" larger than the compression ring which will end up giving you the needed space for some 1/8" closed cell foam if you are covering it with fabric in the end.

Once you've got the ring traced, cut your shape out and it should look like this:



From there, you need to build up the sides of the template with scraps of wood so that you'll have something to clamp the bending plywood to. I used some scrap 3/4" plywood I had cut into roughly 1.5" strips. Glue them on one layer at a time, leaving a little bit overhanging the original plywood template. After the first layer dries, use a router with a template bit to trim back the sides to match the template you traced. Do this at least twice more, to end up with three layers of 3/4" plywood (2.5" tall jig in total).

You'll end up with a jig that looks like this:




Step 2 - Make a ring:

Now, the harder part... Get some 1/8" bending plywood. You want the stuff that bends along the 8' length (aka "hamburger" not "hotdog" orientation). Measure your window, wall panel, etc., to determine how deep the ring needs to be and be sure to add an extra inch or so that you can scribe and trim off. In the end, I went with 3.5", mainly because that’s how wide the jaws of my clamps are, and it ended up perfect.

Cut enough strips from the plywood to wrap around your jig 3 times (this seemed plenty for me). You'll then need to trim them to length. each layer of the ring will require two pieces of plywood as the total circumference is larger than 8'

Start with the first layer and clamp a strip against the jig. Be very careful bending around the corners as it will break if you're rough with it. Clamp it as needed to hold in place so that you can measure the second piece needed. Cut and place that piece.

Then continue for the next two layers. When clamping on new strips over each layer, it's easiest to un-clamp one side at a time, clamp the new strip on, then move to the next side.

It's good practice to clamp them now before they have glue on them, and you need to measure each layer as they are different sizes due to the fact that the overall circumference increases with each one. Its also a good idea to mark each piece so you know which layer it is a part of.

Once I had clamped together as a mock-up, I cut some cauls for the four sides to use in the final glue up.

Once that’s all done, you can start gluing it all together. I laid a sheet of clear plastic against my bench so the ring wouldn’t stick to it. I started with the first layer clamped down and glued one side of the second layer. Use a lot of glue since you aren’t applying to both sides and work pretty quickly. I'd recommend using a roller, spreader, etc., to make the process go faster. Start clamping the second layer just as you did when you measured it. Then do the third. Once the final layer is glued and clamped, you can take off the clamps one side at a time and add the cauls you cut earlier. I wrapped them in plastic to prevent sticking. Then tighten everything down really well and make sure everything is positioned correctly.

It should look about like this:




Step 3 - Scribe to fit:

Once it's dry take all the clamps off and pop out the ring. I then added some 1/8" foam on the corners and sides to give it its final width. The foam also gave it just snug enough of a fit over the window to hold itself in place:



While the ring is on the window, and probably with someone holding it there, you'll now need to scribe the ring where it will meet the wall panel. This is where my process will likely differ from others...

A bit of back story: I had originally thought I would upholster the van body around the window, and have a wall panel that just sat on the opening. I got as far as cutting a wall panel to fit. I then realized that to do that I would have had to remove the compression ring on my window which I decided was not a good idea and was possibly opening a huge can of worms.to open a huge can of worms. Additionally, after seeing the panel, I thought it would just look a lot better to make a proper ring.

So, I had the benefit of having a wall panel in place that I could use as a reference plane when scribing my trim ring. If I did not have this, I'd probably cut a 1-2' long piece of 1/4" plywood that was about 2" wide. I'd press that strip against the wall of the van as if it were a wall panel and trace the outside edge of it against the trim ring.

Once that's done pull the ring off. You'll be left with a line that should be exactly where the *outside* of the wall panel would sit on the ring. Since you want the ring to meet the *inside* of the panel, you'll need to mark another line 1/4" below the first one. Cut the trim ring along that second line with a jig saw to get your final shape.


Step 4 - Make attaching battons:

You'll need something to screw the ring and wall panel to, so cut some strips of wood for each side. For the top and bottom of the ring, which are straight, I cut 1" strips out of 3/4" plywood. For the sides, which have a curve to them (which will need to be cut/trimmed), I cut 1.25" strips from two pieces of 3/4 and 1/2" plywood glued together.

As the sides of the trim ring are curved in two dimensions, making these battons will be a little more difficult. To do this, hold them under the ring and trace the ring's side curve on them. Cut that with a jigsaw and fit them on the ring. Hold them on the front of the ring so that the lowest points (on the outside edges) are even with the ring and mark the curve of the face of the ring on them. Cut that with a jig saw and see how it fits. If needed you can very carefully template route them once they are screwed on. Since the top and bottom are flat on both planes, you don’t need to do any cutting of those battons to get them to fit.

Screw the battons to the ring, screwing through the ring to the batton. If your side battons aren't super flush, you can now use a template router to very carefully trim them back to match the front edge of the ring.

Put in place it should look like this:



Step 5 - Attach to the panel:

I'll assume here that you've already got a wall panel scribed to fit the wall of the van. Place the trim ring back on the window, gently held in place by the 1/8" foam. Take some more of that thick double-sided tape (or VHB) and put it on the battons. Uncover the other side of the tap and then screw the wall panel on where it will be. Press the panel firmly into the ring and tape you've put on. Be sure to apply a ton of pressure.

Then gently unscrew the panel and remove it. Hopefully the ring is still stuck on in the right place. Likely, the sides will un-stick as the wall panel won't hold that curve from tape alone... that’s fine as long as the top and bottom are in their same spot.

it should look like this:



Now, without moving anything, clamp the ring to the panel and trace around the inside and outside of the ring onto the panel. You'll need to pull off that temporary 1/8" foam first.

Unclamp and remove the ring. Cut the wall panel ~1/8" outside of the line you just drew to get a rough hole where the window and ring are. Then put the ring back on, lining it up with the lines you traced earlier. Now is the time to temporarily screw the ring to the wall panel (you'll need to take it off to cover later). Once that’s done, use a router with a template bit to flush trim the panel to fit the ring.

You should now have a trim ring that fits the window and a wall panel that fits the trim ring. Ready for paint, upholstery, etc...

It should look like this:



 
H

hmbltn

Guest
Super timely. Thanks a bunch for sharing. I really want to finish off my Crew window with a similar trim ring, just didn't quite know how to approach it. This helped a ton!
 

alexganenco

New member
Looks great! BTW - where did you buy the bending plywood? I am having a hard time sourcing it since the local Home Depots/Loewes don’t carry it. Thanks in advance!
 

Xdemolle

New member
very nice! Thanks a lot for posting - do you think you could do the router flush bit in the Van instead of pulling it out ?
 

bcman

Active member
Very nice work on the trim ring. But let's talk about that awesome headliner! How'd you do that?
 

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