Diamond Divided Lights | Popular Woodworking Magazine

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These doors are all centered around corners: learn to split them in two using geometry and it’s a breeze.

WWhen I enter the American Decorative Arts Gallery at the Peabody Essex Museum in Salem, Massachusetts, I am always attracted to a large federal piece that was built by Cotton Bennett in my hometown of Beverly, Massachusetts. My research revealed Bennett’s close ties to Thomas True, the New England turner and the engraver Samuel McIntire, who contributed to the tour de force which is this “Secretary of the Lady” of 1809.

Maple and mahogany. Astragal moldings of the same species as the door frame are located above thin hardwood bars below to form a solid structure.

There are a number of stunning details, such as the fine spiral mahogany combined on the bottom drawer and the mahogany on the horse on the fall front. The horse satin panel, which supports the McIntire golden eagle in the upper central part, is balanced with the same material that crosses the lower apron of the front of the carcass. The frame is accentuated by crossed rosewood and mahogany and supports two golden flame terminals with bay leaf carving. I am also amazed by the small multi-colored band that surrounds the fall front and accentuates the satin wood panel.

But what really gives this piece its presence is the construction of the door: diamond panel lights made of maple bars and small astral mahogany moldings.

So I discovered how to make bright doors divided into diamonds of any size; I share the pictorial process with you. Before diving, study the drawing below and figure 12: those show the four angles that are cut in two to find the complementary inclination angles.

1) Drawing. Make a life-size drawing to determine the oblique angles for the bars that form the underlying structure – set a beveled square on each discrete corner, then bisect those corners.

2) Diagonals. Install 1⁄8 ″ thick maple bars (the same width as the frame elements thickness) from corner to corner. Hit a center line using a long straight positioned where rails and posts meet to form internal corners. Scribe lines halfway through the thickness of the bars (1⁄16 ″) parallel and on both sides of this center line.

3) Fitting fit. Make cuts in relief on the lines of the scribe with a rear saw, then equalize with a thin and sharp chisel so that the bars fit perfectly.

These are the overall X-shaped diagonals.

4) Lap layout. To arrange the lap joint where these bars cross in the center, lift the frame and insert one bar halfway from the back and the other halfway from the front. Stiffen the thin rods with the slats fixed in place with a pair of large binder clips – this helps keep them straight as you write the thickness and angle of each rod on its opposite element.

5) Scribe then cut. Extend the scribe’s lines from the edge to the face of each bar, then saw and draw them for a ride together.

6) Large diamond. To install the remaining four bars, write a center line on each rail and style; the bars will be aligned with them, crossing the bars from corner to corner to form a large diamond in the frame.

Use corner no. 4 for the tracks and the corner n. 2 for the styles to determine the layout of the notches.

Then cut the notches in the rails and stiles with a saw and chisel.

Structure below

7) Miter the bars. Determine the lengths of the bars that make up the large diamond by placing the bars on the frame and marking them directly from the job.

For precise angles at the ends of the bars, cut them with a sharp plane on a cutting table with bisected angles no. 1 and n. 3. The image on the left shows the shape of the notch and the slanted bars for the guides (top and bottom); on the right is the shape of the notch and the slanted bars for the styles (sides).

8) Lap-joint the big diamond. After adapting the bars to their notches, mark the joints directly from the job and cut them as you did with the diagonal bars.

This takes care of the initial adaptation of the underlying structure to which you will connect the astragal moldings. Remove the bars and set them aside.

The key is to start with a flat, square mortise and tenon frame. Make a life-size drawing of the door; work from one corner to another and from the central lines on the rails and steps to arrange the corners of the bars that support the moldings.

Astragal frames

9) Rabbits the loom. Route a surface beat on the rails and steps. Once you’ve squared the corners, glue the bars in place.

10) Angled. Tilt the non-grooved astragal molding strips (at 45 °) to fit them on the inside edge of the door frame – but to fit them flat, you will first need to cut (with a chisel) the ends of the diagonal and the diamond bars back to the width of the moldings.

For moldings, cut a piece of material about 3 “longer than the diagonal bars and mill it 3/8“thick. Allow approx 1/2“In width from 12 to 14 pieces (ie from about 6” to 7 “). This gives you some extras.

11) Layout positions. The mouths of the birds in the perimeter molding strips (in which the truncated internal moldings fit) are located by placing a short length of molding on top of the bars leading to that corner. Slide the sample piece onto the edge of the door frame, then adjust a knife on that piece to write a line indicating the cut. Set a beveled square on the line and use it to mark the corner on the back of the perimeter molding piece.

12) Bisection of corners. In this door, there are four discreet angles that must be determined to fit the interior molding pieces. Place a bevel on each one, then transfer them to the corner table to divide them; this determines the angle of the mouths of the bird that is cut in the perimeter molding and the oblique angles for the ends of the 16 internal pieces of the molding.

13) Corner table. The numbered designs on the corner table correspond to the thicknesses as numbered on the left. The central lines are the four bisected corners necessary for this door.

Straighten and square the edges, then choose a router tip, a molding plane or a scratch that will cut to 3/16“Heel. Cut a bead on the two long edges, with the profile centered on the thickness of the 3/8” action.

14) Make the cuts. Now stretch and cut the bird’s mouths into the inner edges, where all the bars are cut into the door frame, using a hand saw and chisels. Rail molding: cutting angle no. 4

Molding style: corner bisected n. 2

Frame angles: angles bisected n. 2 and n. 3

15) Miter the moldings. There are 16 pieces of internal molding to be cut and cut off at the correct length and angles. Mark the lengths from the support bars and add an inch or two to the miters. Each piece gets four miters (two on each end). The molding can rest on the back for half of the oblique cuts on each, but on the other half, it must be turned upside down so that the profile faces the table of the machine gun.

Set the table saw fence to 7/32“, And tear off the edges you just edged. Repeat this process until you have enough pieces to model, plus a few extras.

16) Oblique trough. A trick that helped me cut the miters when the piece is resting on its display side is a strip of material of the same width as the molding, which has a 3⁄16 “groove in the center.

Now set the router table with a 1/8“Bit straight and cut a 1/16“- Deep cable centered on the back of all but four molding pieces. This groove fits the maple bars to help hold the molding in place and provide support. Non-grooved pieces are installed in a batting around the perimeter.

Tanning the internal perimeter of the frame (then square the corners) to accept the external molding. The depth of the ledge should correspond to the depth of the groove you plowed into the back of the moldings (in this case 1/16“) And the width should be two thirds of the molding width (in this case 1/4)“. This dowel helps you align the perimeter molding and sets it to the correct height so that it matches the moldings you will place on the top of the bars. With the beat done, glue the maple bars in place.

Now follow the steps below to adapt to the moldings.

Bisecting corners

1) Set a beveled square on the first corner that you need to bisect.

2) Find a piece of plywood that is straight and square. Along one edge, write a baseline.

3) Using the beveled square set as a reference, cut a line that intersects the baseline.

4) Take a pair of dividers and place the point at the intersection of the baseline and the corner line.

5) Extend the leg of the dividers at a convenient distance and write a bow.

6) Where the arc intersects the corner line, position the divider point.

7) Extend the divider leg more than half the arc distance between the baseline and the corner, then write an arc.

8) Place the point of the dividers (same setting) where the arc intersects the base, then write an arc that intersects the previous arc.

9) Position a straight edge so that it crosses the previous intersecting arcs, as well as the intersection point of the baseline and the corner line, then write a blade.

10) Set your chamfer on that line; this will give you two exact complementary angles.

Tits series of steps will help you determine any miter angle (in this case the angles for the bird’s mouth and the astragal moldings) and increase your geometry play. You could try to figure out how many degrees the angle is then divide it in half, but quite often this will result in an odd number – like 34,675 degrees – which is difficult to set a beveled square.


Create a Miter shooting board

One board, four mitres. A submachine gun table (this is made with an old bench hook) includes all the shooting angles for this diamond shaped door.

Mmake a board with the four fences needed to plan the four corners at the ends of the internal astragal moldings (two on each end).

Tools. The planes that I find particularly useful for mitigation are shooting plan no. 51 by Lie-Nielsen and cutting plan no. Both lie perfectly flat while shooting a machine gun.

Use your sliding tapered square and pencil to transfer the four bisected corners from the corner table to a bench hook. Align a block of hardwood to each line, with the corners slightly hanging on the edge, then glue and nail the blocks in place. Slide the edge of the board through the circular saw to cut the corners at the ends of the fence.

Matching numbers. The numbers marked on the paper correspond to the corners of the fence on the machine gun table (and to the corners of the moldings and mouths of the birds).

Align the pieces to be modeled to the correct fence, with the end at the edge of the table. Shoot at the ends with a plane that has an iron ground and smooth straight and square, and which projects parallel to the bottom of the plane. This plan configuration ensures that the miter saw has only one corner when it is cut.

– PL

Final steps

After cutting all the miters by molding, put glue on the back of the perimeter pieces and glue them in place. Then glue each inner divider onto the corresponding maple bar.

The support structure, plus the long grain long grain of the mold above, offer a lot of support for the glasses.

This all sounds much more confusing than it is. While there are many steps and the mitres must be absolutely active for a crisp appearance, understanding the geometry will help you do it well, regardless of the size of your door. Remember: the key to success is to start with a square and flat frame!

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