Canadian Woodworking

Build custom interior doors

Author: Robert Zakarian
Photos: Robert Zakarian
Illustration: Len Churchill
Published: February March 2022

Solid hardwood, coupled with a unique design and time-honoured joinery, makes for a stunning look.

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interior door drawing
interior door materials list

Building custom doors is very rewarding. Stock interior doors are usually constructed from MDF and cardboard. Although these doors are cost efficient, they are boring in my opinion. Upgrading interior doors to solid wood not only adds value to your home but also allows you to design doors that fit the style of your home. This project will focus on a door I made for a linen closet. The door faces the staircase and provides an attractive look. This particular door is standard 80″ × 18″ × 1-3/8″. The measurements in the materials’ list are all final measurements. You would need to adjust the measurements to the size of doors you need. I’ll go through the calculations which can then be extrap­olated to the door size you need.

Two Different Tenon Lengths
Zakarian marks the edges of the rails either 1" or 2" from their ends. These lines help him machine the tenons to the correct length. He stops moving his router table fence away from the blade when the router bit stops exactly at the pencil line. This tenon will be for one of the outer joints, as it will be 2" long.

Two Different Tenon Lengths

Center the Bit
The router bit to cut the tenons needs to be set up so it’s centered on the stock.

Center the Bit

Test Cut
A test cut will help determine if the bit height is set properly. Zakarian is making a test cut now, but will remove the upper half of this cutter when making the tenon joints on his door.

Test Cut

Long Tenons
With the height set accurately, Zakarian removes the upper portion of the bit. This will allow him to move the fence away from the blade far enough so tenons of any length can be cut.

Long Tenons

Set Up for Grooves
After switching to the grooving bit, Zakarian adjusts the height to match the groove dead center on the panel’s edge.

Set Up for Grooves

Ready for Action
With the height dialed in, the grooves to accept the panels can now be machined.

Ready for Action

All Four Edges
Once the grooves are cut into the edges of the center stile, Zakarian machines the same groove on both of its ends. This is the only workpiece that receives a groove on its ends.

All Four Edges

Freshly Grooved
With the 2" long tenons cut on both ends of this outer rail, and the groove machined into its inner edge, this workpiece is almost ready for assembly.

Freshly Grooved

Coming Together
After being machined multiple times, this joint is about to be brought together for a test fit.

Coming Together

Remove Some Waste
To make it easier to mortise all the parts, Zakarian removes some of the waste with a drill bit.

Remove Some Waste

Cut Some Mortises
A hollow chisel mortiser is a good way to machine deep mortises in these workpieces, though a router or hand tools could also be used. The finished mortises are flush with the sides of the grooves.

Cut Some Mortises

Notched Tenons
In order for the tenons to fit around the 1/2" wide shoulder beside the mortises, you can use a bandsaw or hand saw to remove 1/2" of material on the edge of the 2" deep tenons.

Notched Tenons


Make Some Ls
Two of the three panels are L-shaped. Keeping them slightly oversized is a good approach, as the outer edges can be trimmed to size once the glue is dry.

Make Some Ls

Perfect Match
Although not all the joints are glued, mating them while in the clamps can be easy.

Perfect Match

Squared Off
The finished inside joint, ready to be sanded and assembled.

Squared Off

More Light Taps
A sharp chisel is mandatory for this step. After that, more light taps always trump fewer heavy taps with your mallet.

More Light Taps

Final Assembly
After a dry fitting and sanding, it’s time for some glue and clamps. Ensure the assembly is sitting flat while it dries.

Final Assembly

Wood selection

Poplar has a pleasing, simple wood grain, and is easy to work with, light yet durable, accepts paint well, and is cost effective. Moisture content of approximately 6% to 8% in kiln-dried poplar makes it a stable wood for this project

Choose the lumber and mark all stock for stiles and rails. Although you will increase the waste factor, it’s safest to rough cut the parts long when dealing with tenons and other joints. Using the jointer and planer, work stock down to the final thickness of 1-3/8″. You may be able to use 6/4 stock for this project if the stock is very straight, but just remember you will only have 1/8″ extra thickness to work with. My wood mill didn’t have any 6/4 so I had to use 8/4.

Once all parts have been planed down to exactly 1-3/8″ thick­ness, cut all the stiles and rails to their final length and ensure they’re square.

Rails need tenons

Let the fun begin. Once all the parts are cut to size, it’s time to fabricate tenons on the rails. Label all parts of the door. These will be important references while machining the grooves, mortises and tenons.

I used the Freud door kit #99-268, though there are other options on the market. Freud has many door profile kits, but this particu­lar one (Roman Ogee) is my favourite. Please follow all guidelines indicated from the manufacturer for this set and follow safety pre­cautions for your router setup. Freud has extensive instructions that come with the set, but I will also explain some of the setup details here.

The measurements discussed here are for an 80″ high × 18″ wide door. Other cutters may have different dimensions, so the lengths of your rails may need to be different than mine to obtain the same dimension of door. I recommend drawing your door dimensions out full-size before starting to build it.

To determine the length of the rails, start by determining the length of the tenon for the outer rails. For strength, I want tenons half the width of the stiles, therefore 2″ long. Given the door’s final width is 18″ and each stile is 4″ wide, the formula is 18″ minus 4″ minus 4″ equals 10″. Next, add 4″ (2″ tenon length × 2 sides) to account for the two tenons on the ends of each rail.

The calculation to determine the lengths of the other rails (the rails other than the outer top and bottom rails) is as follows. The visible length of the short center rail is 4″ and there are 1″ long tenons on each side of this rail. Therefore, 4″ plus 1″ plus 1″ equals 6″. You’re probably wondering why I went with 1″ tenons here, instead of 2″ tenons. These parts are less structural than the outer two rails and stiles, so less strength is needed. The lengths of the two inner rails are calculated in the same way.

With all the rails cut to length, you can mark a tenon location line on the edges of the rails, near their ends. Add a mark 2″ in from the ends of the two outer rails and 1″ in from the ends of all the other rails. These lines will give you something to shoot for while machining the 1″ and 2″ long tenons.

Router bit setup for tenons

This step is the most important step in order for the tenons to fit perfectly in the mortises and for the parts to be the correct length and produce a door that’s sized properly. First and foremost, make sure your stock is exactly 1-3/8″ thick. Any deviation from this thickness will offset the bit and your pieces will not line up to have a tight joint. Take time and care to align everything properly and use test pieces to test the cut before machining the actual rail.

Usually mortises are machined first, then the tenons are machined and fine-tuned to fit the mortises, but that’s not how I made these doors. Because I used a hollow mortiser to create the mortises, the width of the mortise was set in stone. I made a test mortise so I could double check that the tenons I was making fit the mortise perfectly.

Start with some scrap

On the end grain of a piece of scrap wood, mark a line 1/2″ from the top face and 1/2″ from the bottom face. The material between these two lines is the thickness of the 3/8″ thick tenon. Set up the tenon cutter from the kit #99-268 so the lower cutter is below the lower half of the 3/8″ mark and the top above the top of the 3/8″ line. If the stock is exactly 1-3/8″ your tenon will be exactly dead center on that board. If the board is not exactly 1-3/8″ you will need to adjust the cutter up or down to locate the tenon dead center.

Set up your featherboard on your router table’s fence, and run a piece of scrap through, making sure downward pressure is applied equally as the cut is made. After the test cut, ensure the tenon is centered on the stock. If there is a dis­crepancy, readjust your bit up or down to center the tenon. Keep your final scrap test piece, as this will be used to align your stile cutter later on.

Once you’re satisfied with the adjust­ment, you can start to machine the tenons. They will all be controlled by a miter gauge while they pass over the rotating bit. To make both the 1″ long and 2″ long tenons, the top half of the cutter needs to be separated from the bottom half. Do not adjust the height. Move the fence away from the cutter and remove the top portion of the cut­ter as per the manufacturer’s instructions. These cuts will be done in many small increments by moving the fence back about 3/16″ to 1/4″ until the tenon of the desired length is reached. This is where the lines you marked on the edges of the rails come into play, as the inner portion of the cut should stop exactly at the pencil line; the router bit should never cut beyond this line.

Make sure to keep the router fence parallel to the miter gauge track as you move the fence away from the bit. It’s best to start with the shortest tenons, in this case the 1″ tenons. Once the 1″ tenons are completed, continue the passes in the same fashion until 2″ tenons are cut. With the tenons complete, you can move to the sec­ond cutter in the kit which is for making the grooves to accept the panels.

Router bit setup for the panel grooves

With all the tenons cut, install the groove cutter in the router. Aligning this cutter to the board is fairly simple. Align the top of the cutter with the top of the tenon and lock the router in place. Make a test cut and compare it to the tenon cuts to ensure a good fit. If the parts fit perfectly you can run all the stiles and inner portion of the rails while applying equal downward pressure while each workpiece is being machined.

Make sure to run both ends of the center stile, since it will mate with the upper and lower short rails and accept the panel at its end.

Mortise the stiles

For this step I used my hollow mortiser, however, you could also use a router equipped with a long straight router bit. Starting with the long stiles, mark where the mortises should be made.

For my door, the measurements are as follows: for the hinged stile, measure down 1/2″ then mark for the width of the mortise. The 1/2″ gives the tenon a shoulder to butt up against and prevents glue from dripping out. Mark the same measurement from the bot­tom of the stile. For the center mortise, center it on the stile. For the stile with the handle and latch, measure the same as above to accept the upper and lower rails, then measure down 8-1/2″ from the top and mark off for the mortise. Repeat this measurement for the bottom portion of the stile. For the center stile, one mortise is centered on its length, while on the other edge the two mortises are at the ends and will accept 2″ wide rails.

Now that all the mortise locations are drawn out, set up the mor­tiser with a 3/8″ chisel. Prior to hollowing out the mortise I like to predrill the mortises to remove some of the material. This tech­nique puts less strain on the chisel and helps prevent binding. Set up the mortiser so the chisel is dead center on the board. First, center your chisel with the groove, then end-for-end the board and ensure the chisel lands in the exact same position. If it doesn’t, you will need to adjust the fence front or back to get the chisel dead center. Proceed to hollow out the mortise, keeping in mind the mortises on each of the outer four corners are 2″ deep, while the rest are only 1″ deep.

Dry fit the frame and pre-sand

Before dry fitting the door, you will need to notch the tenons on either ends of the upper and lower outer rails because we left a 1/2″ shoulder during the mortising step. On the bandsaw, cut 1/2″ off the outer edge of each of the tenons. Now dry fit all the parts and tweak the mortises, if required. If prior steps were properly per­formed, these parts should fit together nicely with minimal force.

At this stage I usually sand with 120 grit, and make small repairs to imperfections in the wood.

Break out the panels

This door has three panel inserts. Two of them are L-shaped and one is straight. For the straight panel, cut your stock and square the panel to its final size of 4-7/8″ wide by 34-7/8″ long. There’s a bit more work involved in the L-panels, as these parts can be a little trickier to get straight and true. Dress the main panels and the extensions to final thickness before cutting them to width and length.

There are two parts that come together to make the L-panels. Essentially, the main section is machined, then a small exten­sion is added to one side of each of the main sections. The final dimension of the extension should be 10-7/8″ wide × 4-7/8″ long. For the vertical dimension (or the distance along the grain) of the extension, I crosscut the piece to its final dimension of 4-7/8″ then glued this piece to the main portion. Just make sure the piece is wider than 10-7/8″, as it can be trimmed to width after it’s assem­bled. When gluing these parts together I flipped the two L-panels to face each other, making a rectangular frame. You can also add a few dowels or Dominos to assist with location. Another approach to give you more flexibility if movement during glue-up occurs is to leave the main section long. That way, if the extension shifts at all during glue-up, the L-panel can still be trimmed to final size. Once the glue has set, cut the L-panels to the correct dimensions. Remember to dress and size the other rectangular panel as well.

Raise the panels

For this step I used the Freud raised panel router bit # 99-520. There are three raised panels to shape: two L-panels and the cen­ter rectangular panel. I set up the router for the center panel first. These panels are sized so a 3/8″ deep tenon fits the grooves machined into the stiles and rails machined previously. Set the top of the cutter 1/2″ above the table. Set up the fence so small amounts of material are removed at a time.

Using a test piece, make several passes until the bearing of the cutter is flush with the fence. Remember to alternate the passes, i.e. cut the top, then flip the board over and continue with the bot­tom, then move the fence back a bit. Make passes to all the straight sides on these panels first, including the external edges of the two L-panels.

Once all the straight sides are complete, remove the fence from the router table and insert a starting pin on your table. You can also clamp a piece of wood to the table to act as a starting pin if your router table doesn’t accept one. This step is very important as it will allow you to slowly guide your piece into the cutter, providing sup­port and preventing the wood from getting violently sucked into the cutter. Proceed with machining the remaining parts of the L-panels. If you’re worried about removing a lot of waste with these passes you can lower the bit and make multiple passes, raising the bit each time. Just be sure to make the final pass with the bit at the proper height.

A third option to raise these panels is to first machine a few passes on the inner edges of the L-panels to remove some of the material, then proceed to set the bit’s final height. At that point you can machine all the straight edges, then remove the fence, install the starting pin and rout the inner edges of the L-panels.

Dry fit and adjust

Dry fit the panels in the grooves to make sure the panels fit nicely. If they’re too tight you might have to repeat the process and apply a bit more downward pressure while feeding the panels through the cutters or raise the bit slightly.

The inner corner of the raised panel will need to be cleaned up using a chisel since the cutter will leave a rounded corner. To clean these four corners (two sides per panel), extend the lines and clean the waste out with hand tools. Score the lines with a chisel, then carefully cut away the excess, then clean up the corner with a scraper.

Dry fit panels and preassemble door

Sand all panels, then dry fit all parts of the door. If no adjust­ments are needed, glue all the rails and stiles and let them dry for 12 hours. Leave the panels free of glue, except for maybe a bit towards their centers, as this can keep the panels from shifting after assembly.


Once the glue has set, machine the hinge mortises and the hole for the handle. Give the door a final sanding and break all the edges. I stained the door with a black water-based stain from Saman, then applied two coats of 5° water-based lacquer from Aqualux. The lacquer was sprayed using my HVLP.
The project took me about six days to complete, from start to fin­ish. I have made many variations of this door, and although there are simpler ways to make doors, I really like the fact that these are unique and can be customized to the interior of any home. Proper layout, care­ful measuring and accurate machining are all good skills to have when making these doors.

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