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Making Arched Top Raised Panel Doors
Introduction
Sooner or later you will want to create the style of door referred to as an Arched or Cathedral Top Door. Hopefully, you will already be familiar with standard Raised Panel Door construction before you begin. If you are, that's great, if not, you can take a look a Making Raised Panel Doors first. Most of the same skills that are required to construct Arched Top Panels are the same ones needed to construct Square Toped Panels, the difference being in Laying out the Arch and Shaping the Arch. Once you understand how this is done you too will be making beautiful doors in no time at all. We will be using the standard "cope & stick" joinery for this project. The use of the table saw, router table (two of them), jointer, planer and shaper have all been employed here, this doesn't mean you need to have all these tools to produce fine looking doors, it just makes the job easier.
Choosing Stock
Every job must start out with a good supply of materials. Whether you plan on purchasing your stock "ready" milled or you will be dimensioning it yourself, it's always wise to purchase the best stock you can afford. We have always dimensioned our own stock so, that's where will go from here. We will be using hard maple for this project.
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Stock Preparation
The first thing to do when it's time to start dimensioning your "rough" stock is to cut it into sizes that are close to the "finish" pieces that you will need. The greatest reason for this is that it will produce far more usable pieces from our stock. Once you have cut your stock to their rough dimensions you will need to begin to "dress" it. This is the process of make you stock flat, straight, square and it's final thickness.
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The two "best" machines for this are, the Jointer and Planer. This is not to say that a hand plane wouldn't do a fine job. . .it would just take a bit longer.
Stock Glue Ups
Panel glue ups follow the same rules as other glue ups do, you try your best to match grains on the individual pieces. The pieces should be milled to their correct thickness, their edges should be jointed square with the face of the piece. This will ensure a "tight" joint at the glue line. You should leave the panels in the clamps for at least and hour if your using white or yellow wood glue and 24 hours if your using polyurethane glue.
Determining Rail & Style Measurements.
At this point we might as well go through the whole process of determining the dimensions of any door. I use the term any because it should work for any door you would need. After you have determined the "overall" size of your door you can then cut all it's component parts. In most cases that will be two (2) rails, two (2) styles and one (1) panel. Let's also say that the rail and style widths will be2-1/4" and their thickness will be 13/16". If you were to make a door that is 15" wide by 21" high, it would brake down as follows;
The style measurements are equal to the overall length of the door. So for this door they would be;
21" long by 2-1/4" wide by 13/16 thick.
The rail measurements depend on the cutter you are using. It would be for you to determine what the setback cut is on your particular cutter. The one I'm using has a 3/8" setback. What the setback is, is the amount of wood that the cutter removes when making the "stick" component of the joint. This is the cut that is made on all the "inside" surfaces of the rails and styles.
So, if your overall width is 15", your rail lengths would equal;
( 15"- (2-1/4" * 2) + (3/8" * 2) ) or
( 15" - 4-1/2" + 3/4" ) or
11-1/4".
I've found that a top rail of between 4-1/4" and 4-1/2" works nicely. I'll use 4-1/4" for my example. Once you've determined the length of the top and bottom rails you can cut them. You can use a MS, CMS, radial arm saw or a cut jig, I prefer to use a sliding cut table like the one pictured below. It has an adjustable stop for repeatable cuts, it's very accurate.
Your final Top Rail would then be 11-1/4" long by 4-1/4" wide by 13/16 thick.
Your Bottom Rail would then be 11-1/4" long by 2-1/4" wide by 13/16 thick.
Once you've cut our top and bottom rail blanks to length, it's time to make the Rail Templates
Laying out the Rail Template Arches
Cut a piece of 1/4" or 1/2" plywood the same size width as the rail who's templates this will be but, about 2" longer in length. You will need to make a template for each different door arch you have. The object when laying out the Top Rail is to get the center of the rail the same width as the styles and bottom rail. In this case the styles and bottom rail are 2-1/4" wide. First you need to determine the center of the top rail blank, you can do is quite easily by drawing two lines from opposite corners, where they intersect is the center of the rail. Once you locate the center, measure down the width of the other styles and bottom rail which is 2-1/4". The next step is to determine the radius of the arc that is created by drawing a curved line from one corner of the rail, through the center mark 2-1/4" down from the top and through the other corner of the rail.
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Some of the tools you will need are a calculator, a board roughly equal to the thickness of your rails and styles and about 2 ft square, a set or trammel points, a trammel beam and this formula;
R = ((((L/2)2)/H) + H) / 2
Where L is the length of the rail blank
And H is the measurement from the bottom of the rail to the point along the center that is 2-1/4" down from the top. In this case 2".
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With the information that we now have it's easy to determine the radius R.
L = 11-1/4" / 2 which is 5-5/8".
5-5/8"2 = 31.64.
31.64 / 2 = 15.82.
15.82 + 2 = 17.82.
17.82 / 2 = 8.91
R = 8.91.
Which is close enough to 8-29/32".
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On the board draw a center line straight down. You will use this line to align with the center line of your top rails. Set your trammels on the beam at the desired spacing, which in this case 8-29/32". Hold the pencil end of the trammel on the intersection point on the rail and let the other fall where it will on the center line of the board. Press firmly down on the pointed end so it just "sticks" in the board, then scribe the arc. If all goes well it should go from corner to corner through the center point. We now can processed to make the template to shape the top rail.
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Making the Top Rail Templates
After the template is laid out you will need to cut the arc out. You will have to make a template for each different door arch that you have. There are a few ways to do this, the one that I chose, is to use the bandsaw. When cutting the arc out, make sure to stay about a 1/16" away from the line. You can use a drill press or spindle sander to sand cleanly to the line. Once you have made the template align it with the rail blank and scribe the arc. Follow the same procedure when cutting the rail blank as the template. The only difference will be that you won't clean it up with a sander, you'll use a router table.
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Making the Top Rails
With a straight cutting bit with a bearing mounted in the router table you are ready to "shape" the top rail. There are again a few way to fasten the template to the rail blank. I like to use three brads to fasten it to the back side of the rail, you can use double sided tape if you like. I have found that the three little pin holes not to be a problem, plus it really holds the pieces together. Once you align the two pieces, the blank should over hang the template by about 1/16" at the curve. You can route the blank flush with the template.
Note: I have never found a need to make a template for the panel of an Arched Top Door.
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Once you have successfully milled the top rails it will be time for you to "cut" the cope and stick joint on each rail top. I use a router table with the copping bit installed to cut the cope. I use a sled as a "backer" and a special holding clamp to route the rails.
The holding clamp is made of a piece of maple about 1-1/2" by 3" screwed to 3/8" x 3/4" x 4" piece of Plexiglas to slide inside the dado slot. The backer is just a piece of MDF with the profile of the cope cut milled on one edge. You can see the whole setup here.
You place the backer in front of the cutter and slide the side of the rail you wish to route against it and the fence placing the "face" against the table. Move the rail about 5/16" off the fence and then slide the holding clamp in the dado slot up against the curve portion of the rail.
You can now make the first pass, once done, move the rail up tight against the fence for the second pass. Each side should require two passes to complete the profile. Flip the rail and route the other side following the same procedure. This will complete both side of the rail. You can now move to route the "stick" portion of the joint.
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To route the stick component of the joint on the rail, I use a second router table setup with the stick cutter installed. The two router table setup saves a lot of time in bit change overs. This cut is made strictly free hand. It looks provocative but, really isn't.
By placing the rail between a Bessey® clamp I've found it really easy to control and be very safe while routing the stick joint.
By also placing a piece of wood 3/8" x 3/8" x 2" in the cope cut of the rail, you can provide additional support for the bearing when routing close to the ends of the rail.
Placing the assemble flat on the working surface of the router table and moving the piece into the rotation of the bit will produce the best cutting action. You should experiment with this to find what is comfortable for you.
With practice, you will become quite good at using this method. You will be amazed at the control you have. You can also add a "pin" to give you some additional control.
Once you cut the top rails you can assemble the frames, with no glue of course, to take measurements for cutting the panels. You can measure from inside to inside along the width less 1/16 and from bottom to high point on the arch for the length, less 1/16". The 1/16" is for clearance.
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Milling the Panels after Glue Up
Now that you have your measurements you can remove the blanks from the clamps you will need to rough sand them with an 80 grit sand paper. You can use a belt or random orbit sander for this job. Only if the panels have large variations will you need to use a belt sander, if not, a 5" or 6" random orbit sander is just fine.
After the panels have been sanded, I joint one side of the panel to produces a straight side. Using that side against the fence of my sliding crosscutting jig, I square all four sides. I've found that milling the panels using a sled mounted on the table saw produces the best results.
Once the panels are cut to there correct sizes, it's time to make the raised panel. You can use several tools to do this job which include a plane, router table, or shaper. I prefer to use my shaper.
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Laying out the Arch Top Panel
By adjusting the radius to accommodate the offset of your "cope & stick" cutters (usually 3/8"), reset the beam and trammel setup that you used for making the panels upper rail by this same offset. You can then draw the arc on the panel as shown to the right.
As in the example about, if the radius for the upper rail was 8-29/32", then the new radius for the panel would be 8-29/32" + 3/8" = 9-9/32".
R = 9-9/32".
This will provide the needed length to the panel to engage the rail mortise.
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Making the Arch Top Panel
Before cutting the panels arc, it would be helpful to "score" the panel at the table saw to help limit tear out and chipping when cutting with the panel cutter. This step requires careful setup, so take your time to get the location and the depth correct.
Once this is completed, you can cut the panel at the bandsaw or by whatever method you chose. I prefer the bandsaw but, a router setup in a jig or even a jigsaw will do just as good. Sand to the layout line to complete the cutting of the arc.
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Having accomplished this, its time to shape the panel at the shaper. If your using a router table the principles are the same.
Start be shaping the bottom and sides, this will also help prevent tear out. Be sure to use caution when using your machines. The use of clamps, hold downs or whatever device makes you comfortable is highly recommended!
Once the bottom and sides are completed you can then shape the arch. I like to use the setup to the right when shaping. The use of a Bessey® clamp works well for me. By passing the panel into the cutter with the panel supported by the in feed fence produces a fine cut.
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Pre Finishing the Arch Top Panel
Before assembling the door components, I like to pre finish the panel before I insert them in to the styles and rails. This step begins with a through sand of the panels using a random orbit sander. Since the panels were sanded to 100 grit before they were cut to size, sanding begins with 120 grit and steps up through 220 grit.
Wiping (cleaning) the panels down with a tact cloth and naphtha bath is a good habit to get into. This keeps the surface clean and free from any residual grit particles.
The panel edges are the most difficult to sand. They require hand sanding to really get the job done well. A piece of sand paper wrapped around a small piece of maple makes a good sanding block.
After the sanding is completed, I apply 2 coats of a 50/50 mixture of shellac to the panels, sanding between each coat. I have found over the years that shellac is the best sealer/primer you can use.
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Assembling the Door
Once the panels are dry, you can then assemble them. This is a critical part of making the doors so take care in the process. Good clamps make the process easier also. Don't apply to much pressure and check that your doors are "square" after you clamp them.
Allow your doors to stay in the clamps for at least 12 hours. Even though you can remove them after about an hour, I think the extra clamp time is just a wise decision. You have spent so much time make them, what is a few hours more. . .
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Finishing the Door
After your doors are removed from the clamps you will need to do a final sanding of the door frames. You follow the same steps as sanding the panels, going through the grits from 120 to 220. Once completed apply between 6 and 10 coats of a wipe on polyurethane, I use my own special mixture ;-}.
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