Desk(s) From Solid Core Door

While I was in my hometown for a few weeks I decided to make a surprise gift for my brother, a new desk. The desk he’d been using was an old writing desk that wasn’t the right height for him nor was the proper depth for a computer. He deserves something better so I decided to make one for him. 

I didn't shoot video of the process but, I edited a short video from the photos, Watch here!

How to view without an account (First, try opening in an incognito window)

This project was exciting as it was my first time working with:

• A solid-core door
• Birchwood ( S4S helpful since I don’t have a planer)
• Quick Fill Burn-in (Wax-like substance) See step 9
• Casters on a piece of furniture
• Threaded Inserts
• Tung oil (Pure)

Tools used

• Screwdriver and Allen Key set (to remove doorknob and hinges)
• Circular Saw
• Jig Saw
• Table Saw
• Chop Saw
• Drill Dress
• Hand drill with Drill guide
• Router with round-over bits
• Sander (I used a combination of a belt sander, Randon Orbit sander, sheet sander, and disc sander.
• Clamps Mostly 6” a few long 36” clamps can be helpful but there are workarounds
• Band clamp
• Hammer
• Chisels
• Combination square
• Heat gun
• Razer blades
• Pliers
• Safety equipment for lungs, eyes, and ears.
• Silicone glue spreader
• Metal Punch/centerpunch/awl

Materials used

• Solid Core Door 
• 1 by Yellow Birch S4S
• 32 ½” hardwood dowels cut to about 5”
• Wood Glue
• 8 Caster Wheels 3 inch Locking Stem Casters, 3/8" -16 x 1-1/2" (Stem Diameter 3/8", Stem Length 1-1/2")
• 8 Large diameter washer for ⅜” wheel stem 1 ½” outer diameter
• 16 Threaded Insert for Hard-Wood, Stainless Steel Thread Inserts 3/8-16
• 8 3/8-16 x 3" Socket Head Cap Screws Bolts, 304 Stainless Steel 18-8, Allen Socket Hex Drive, Full Thread
• Mohawk Finishing Products M320-0011 Black Mohawk Quick Fill Burn-in Stick, 1
• ⅜-16 threaded rod and nut to install threaded inserts
• Pure Tung Oil and scrap fabric for application.
• Sandpaper in grits: 80,120,150,180,220,320,400. 

Usually when I make something I try to satisfy some of these constraints

• Made from reclaimed materials.
• Adjustability, to extend possible userbase and therefore possible lifetime of the piece.
• Lightweight/movable/ ability to disassemble and constructed in a way where it could be reworked into something else if no longer needed/desired.

Project-Specific Constraints

• Comfortable on the forearms
• Ergonomic, the right height.
• To be easily movable in the room (on carpet) for cleaning and reorganization.
•  A second, smaller auxiliary desk to mimic the flexibility and mobility of a currently used TV tray table. 
• Had to be designed and built in 16 days.

The Tabletop Conundrum

I knew I didn’t have the tools or clamps to glue up a tabletop so I had to be creative. At first, I tried to find tables or countertops on Craigslist but failed to do so quickly enough. Then I remembered what woodworker and DVD commentary guy, Matthias Wandel does in some of his projects. While woodworking with discarded wood and broken furniture he has on several occasions used a door as a tabletop. I changed my searches to start targeting solid core doors and quickly found a few good candidates. 

General Info

Solid core doors seem to be less popular these days, probably due to their weight. More common are panel doors for their looks or hollow core/cellular core (honeycomb pattern) doors as they are lightweight and inexpensive. Solid core doors can either be filled with pieces of wood laminated together or be a composite material. The doors with a composite core are filled with a material similar to particle board where pieces of wood chips are glued together under high pressure. The door face is a plywood-like material and it has a thin veneer.

Source: Types of Doors-The Constructor

How to Identify a Solid Core Door

You can tell if the door is a solid core by its weight and its sound when you knock on the center (thanks for the reminder Jeffw23). If it is heavy and sounds relatively low-pitched/deep when you knock on it, then it is likely a solid-core door. To get an indication of if it is composite or solid throughout you may be able to tell from the bottom or top of the door, where it could have been trimmed or by the hole for the doorknob.

Hollow Core Doors

Hollow Core Doors may also work and be a lighter option. I have not cut one open but this is what they can look like on the inside. Maker, Artist, and Youtuber Tim Sway has been making some cool stuff from reclaimed hollow core doors, too!

The rest of the wood in the project is made from Birch. This was my first time working with it. It was one of the lower-cost hardwoods from my local lumber supplier. Apparently, there are over a dozen species of birch native to North America but, yellow and white birch are the most common varieties in furniture making. Less birch is used for furniture making nowadays as it has become primarily used for more utilitarian purposes like plywood, boxes, crates, and interior trim. I believe I purchased yellow birch which has a hardness (Janka Value) slightly higher than both black cherry and black walnut. I looked up its characteristics before purchasing. Generally, it has good workability with a close, mostly straight grain, with some waves. Despite these characteristics, there can be some issues trying to avoid blotchiness when finishing Yellow Birch. I am far from an expert on finishes so I’d recommend woodworking forums for advice but always test your finishes on a board or two before applying it to your projects. 

Sources:

Birch Tree Image-Joseph OBrien

Janka Hardness Values-Wikipedia

Vermont Wood Studios Birch

Trees of the Adirondacks-Wild Adirondacks.org

Spotlight on Birch-Woodcraft

The Table Top(s)

Size 

The door I obtained was about 36” by 96” plenty large enough to make one main desk and a secondary desk to create a sort of detached L-shape. The larger desk was cut to be 56” long and 30” deep and the smaller desk was cut to be 36” long and 20” deep. 

Framing the Top

To be able to round over the edges of the veneered door I knew I would need to attach a frame around the perimeter.  This extra meat would give me space to shape a nice gradual curve on the front edge so that the desk is comfortable on your forearms and elbows. Although it is plenty strong, this frame could also prevent the top from sagging when weight is applied.

The Legs

With the weight of the solid core door, my next challenge was creating a frame that is strong enough to hold the top (and everything on it), as well as strong enough to take the sideload force of being wheeled on a carpeted floor. I purchased 1x material and decided to laminate two pieces together for strength. After deliberation, I decided to make the legs look like the Roman numeral 2 (II). To maximize strength I planned to join the members with a dado joint and reinforce them with dowels. To keep the ability to disassemble, both legs would be attached to the top with ⅜”-16 threaded inserts and bolts. To minimize racking, removable support would span between the two legs in the rear. Despite being different sizes, I kept the legs for both tables the same to reduce the number of unique parts made. 

The Wheels

To keep the table mobile, I decided to use casters, I decided on 3” wheels after looking at them in person at the store. They were the perfect size to roll on medium-thickness carpet. Because floors can be really uneven and slanted I used the type of castor with a lock and a threaded center stem (⅜”-16). Like the top, the frame would be connected to the wheels with the same threaded inserts.   

(Mostly) To Scale Sketching & Unforced Errors

I want to make sure I purchased enough but not too much wood. To do this I used graph paper and laid out the cuts I needed onto boards drawn to scale. This was extremely helpful and additionally served as a cut list. Even with all this planning, I did make two major mistakes while rushing to rework the design. First, when you buy dimensional lumber it’s important to know that the actual size of the wood will be smaller than the nominal dimensions given. Here is a chart for reference.

• Nominal: 1 x 2 Actual Size: 3/4 x 1-1/2
• Nominal: 1 x 3 Actual Size: 3/4 x 2-1/2
• Nominal: 1 x 4 Actual Size: 3/4 x 3-1/2
• Nominal: 1 x 5 Actual Size: 3/4 x 4-1/2
• Nominal: 1 x 6 Actual Size: 3/4 x 5-1/2
• Nominal: 1 x 8 Actual Size: 3/4 x 7-1/4
• Nominal: 1 x 10 Actual Size: 3/4 x 9-1/4
• Nominal: 1 x 12 Actual Size: 3/4 x 11-1/4
• Nominal: 2 x 2 Actual Size: 1-1/2 x 1-1/2
• Nominal: 2 x 3 Actual Size: 1-1/2 x 2-1/2
• Nominal: 2 x 4 Actual Size: 1-1/2 x 3-1/2
• Nominal: 2 x 6 Actual Size: 1-1/2 x 5-1/2
• Nominal: 2 x 8 Actual Size: 1-1/2 x 7-1/4
• Nominal: 2 x 10 Actual Size: 1-1/2 x 9-1/4
• Nominal: 2 x 12 Actual Size: 1-1/2 x 11-1/4
• Nominal: 4 x 4 Actual Size: 3-1/2 x 3-1/2
• Nominal: 4 x 6 Actual Size: 3-1/2 x 5-1/2
• Nominal: 6 x 6 Actual Size: 5-1/2 x 5-½

Source: Lowes

I knew this but assumed that the difference between these numbers would consistent with each size of the board. This is not true. As you can see a 2 x 4 is ½” smaller in both thickness and width than its name would suggest. BUT with a 1 x 8, 1 x 10, and 1 x 12, the difference between the nominal and actual dimensions is ¾”. My silly mistake.

Additionally, since was planning to laminate my boards together to make thicker pieces I needed to double the number of every single part. So for just the legs for both tables, I needed 32 pieces. I had accounted for some of this but not all, so I needed to get more wood. 

As a general rule, It’s a good idea to buy a little extra wood due to imperfections, mistakes, and testing. Wood Magazine recommends at least 15% extra and up to 35% depending on the project and wood. 

Removing Hardware

I was eager to see what the inside of the door would look like when I got it home. First, to get them out of the way I removed the doorknob and hinges with an Allen key and screwdriver. The knobs from my door were quite interesting and solid metal and I set them aside for some future project.  

Rough Cutting

Then with the help of my steady-handed friend Chandler, we cut the rough sizes of the tables with a circular saw/ homemade guide and a jig saw. To prevent chip out of the thin veneer it can be helpful to put painter's tape on the top and underside of the cut and to set your blade so that it doesn’t stick too far through the wood. After the initial cut and some weight loss, I could clean up any jagged lines on the table saw. 

Safety

Also, (you should always, but) definitely wear a mask when working with an old composite door like this, I don’t know exactly what’s in the composite but we don’t want your doctor finding out!

Cutting the Frame

After cleaning up the edges and giving the edge a very light sand I started to frame the top with the Yellow Birch. I ripped pieces about two inches wide. Two pieces for the front edge because I wanted their thickness to be double in order to give room for a larger round-over. To aid in the strength of the table and give more surface area to glue I cut the pieces into an L shape (see attached photo). I did this with the table saw in two cuts and sanded the interior faces in preparation for glue. 

Gluing the Frame

Because I was rushing, I didn’t remove the finish from the underside of the table. It’s nice because it reminds me of what it used to look like but it means that the glue adhesion to the underside of the table is probably poor. Next time I would use a scraper to remove the finish at gluing locations. To apply glue I stood the top on an end, spread glue on the particle board edge, and let it soak into the dry wood for a few minutes. After waiting I would add more glue where needed and to the interior faces of the frame piece. 

While clamping I made sure to make sure the pieces were making good contact and applied clamps in both directions to suck the pieces together. To utilize my small clamps I clamped a long piece of wood to the top and used that to clamp the frame pieces. I worked on one at a time and let them dry for several hours before removing the clamps. 

Rough Sanding

Once all four sides were glued and dried I could try to shape and sand them. I used a water bottle to mark the curves where the sides meet the front and a washer for the others. I cut most of the wood away with a handsaw and then used a belt sander to round the corners. I had cut the tabletop frame so the edges would be a little proud so I chiseled and sanded them down flush on the front and left a small lip of about 1/16” on the back and sides. I had to do this sanding carefully to not sand through too much (I can’t be perfect) of the super thin veneer. 

Routing Roundovers on edges

After the surfaces were rough-sanded I added the round overs to make the desk more comfortable. The front got a 5/8” round over on the top and bottom while the rest of the sides and bottoms got a 1/2” round over. To route the bottom I had to hot glue a piece of wood to my router baseplate to keep it from tipping off the edge (see picture 4) With a rasp and some sandpaper, I was able to ease the transition between the two different-sized round overs. 

Filling Dents and scratches

Next, I wanted to address the holes and dents that were in the door when I got it. To fill the holes I sanded a hardwood dowel down to a cone shape and hammered them in with some glue. With the dents and scratches, I wanted to try something new. I had seen Woodworker and Inventor Andrew Klein make a really interesting table out of OSB where he filled all the crevices with black paint and made an awesome pattern. Inspired by this and a little bit by the spirit of Kintsugi I decided to fill the dents with a black hard wax to accentuate them. I thought the wax would be a good choice because it seemed durable enough and the excess would be easy to remove. 

 I applied the wax with a makeshift scraper made from pliers, a rubber band, and a razor blade. I heated the blade and was able to grab some of the wax off of the stick and spread it into the dents. To further work it in I carefully passed the heat gun over the dent and continued to spread it. With the intention of making it look more cohesive, I later decided to fill the small seams between the frame and the door with wax, too. After this, I started to remove excess wax with my homemade razor blade tool and started to sand.

Sanding

To make sure I was sanding everywhere and not over-sanding, I drew a bunch of pencil lines on the top. To be conservative and lessen the chances of sanding through more veneer I started with 180 grit and worked my way up to 400 by hand, sanding in the direction of the grain. 

After drawing a crude diagram of the leg assembly, I was able to use a simple formula to find the lengths to cut my leg pieces. I labeled the horizontal pieces (A) 20.25” and the vertical pieces (B) 16”. In most cases they were laid out next to each other in pairs or threes on my 1by boards so I cut the rough length on the chop saw and ripped their rough lengths at ~2.6”. Once I had them cut I could laminate two together to get the final thickness. I found that I could fit two legs (or four boards) in most of my clamps so I was able to glue two legs at the same time. You just have to remember not to put glue between the first and second legs. After about two hours I could remove the boards from the clamps and move on to the next few. Lastly, I cleaned up the edges at the table saw so they were perfectly flush and about 2.5" wide.

Dados

To cut the dados for the leg assembly, I used my table saw with a miter gauge and a homemade crosscut sled. I don’t have a dado blade so one at a time I defined the outside ½” of the dados and then clamped four together to clear out the interior. I set my blade to cut away ½”.

I was careless at one point when pulling the sled back towards me with the saw running and it shot back at me, not hard but it made a gash in the pieces. Luckily it cut through the center where I was trying to cut anyway. This could have been prevented by having a longer fence on my sled to clamp to and keeping my hands focused on moving the sled and not holding the workpieces.

At this point, I made sure to do some dry assemblies and find out if there were some pieces that looked or worked better together. I labeled all of the joints on the face and at the mating surfaces. I also stated pairing individual legs together as sets. Doing this, and labeling helped me keep track of which boards had holes drilled on what side and the locations of the holes. 

Drilling Holes for Bolts, Dowels, and Threaded inserts

After the dados, at the drill press, I drilled holes using stop blocks to attach the top and wheels to the legs and to dowel parts A and B together. To attach the top, I drilled a hole with a Forstner bit to make a counterbore so that the head of the socket head cap bolts would sit below the surface. Then another concentric hole was drilled a little larger than the ⅜”-16 bolt to allow it to pass through. The last holes I drilled were for the dowels connecting the horizontal and vertical leg pieces. The ½” holes were spaced over the dado on part A. I used a stop block to keep the locations consistent.

Routing the Roundovers

Next, it was time to put a round over on all of the leg pieces. To ensure I didn't route any edges I wasn't supposed to I marked the edge to be routed with a marker. This is where it started to look like something resembling furniture. I did this with a makeshift router table made from a 5-gallon bucket, an extension cord with a power switch, some weights, and my homemade oversized router baseplate. Because of my homemade setup, I decided to round over the whole length of the piece but it would probably look slightly more professional if you stopped at the point where the dado begins (½” from the end of the board). I did not think I could be that precise and accurate with my setup. Next give it a good sanding, especially the parts that will be harder to sand once it’s glued together. 

Gluing the Legs

I glued the frames together with a band clamp which worked very well. I removed as much excess glue squeezeout as I could with a plastic straw cut at an angle and a wet paper towel for the larger areas. 

Doweling

After letting the glue dry for several hours I could use the holes I’d pre-prilled at the drill press as a guide to drill through the dado joint. I used nearly the whole length of the ½” bit, making sure to clear out chips and take my time between holes to not overheat the bit. Before putting glue on the dowels and pounding them in with a hammer I turned all the pieces upside down to knock out all of the wood shavings. Once the glue was dry I used a handsaw to trim the dowel length and sanded them flush with the surrounding surface. 

Aligning The Legs and Finding the Hole Placement

To locate the legs on the underside of the top, I used a combination square to get an even spacing measuring from the front edge and side. Once I had the location set, I used a handy tool that my grandfather had made. It happened to be the perfect diameter and size to fit into the bolt holes. When placed in the hole, I hit it with a hammer and its sharp point could make a mark exactly where I needed to drill the holes for threaded inserts. To drill the ½” holes perpendicular to the top I used a handy little drill guide. 

Installing Threaded Inserts

With the holes drilled, I installed the threaded inserts. There are two ways to do this, buy a special tool, or use a piece of threaded rod and a bolt, I chose the latter. I chucked the 3/8”-16 threaded rod into my drill and put on a corresponding nut followed by a large-diameter washer and the threaded insert. The nut and the threaded insert can act together like a jam nut and the washer was added to keep the insert flush with the surface, and square. 

I did a test before I even started the project but, I’ve very happy with how the inserts held in the composite door, If I was even slightly worried then I would have maybe tried to add some glue or epoxy into the hole before putting the insert in but the hold was great and the legs were very solid once tightened

To make it easier to put together when disassembled, in hidden areas, I labeled which leg goes where, and its orientation. 

Installing the Cross Brace

Once the legs are in place the cross brace can be installed. I measured the distance between the legs at the other end (near the underside of the tabletop) to help me determine how long to cut the spanning support and keep the legs at 90 degrees. To help me install the piece, I used a few clamps to hold it at the right height and to pull everything together. I drilled a pilot hole through the leg and then screwed in 3” screws to snug everything up.

The Wheels

The wheels can be installed, centered on the vertical members of the legs. Between the dowels drill another ½” hole for the threaded insert and follow the same procedure as explained above to install the threaded inserts (now I see it’s recommended that you drill a 9/16” hole if you’re ⅜”-16 threaded insert is going into hardwood). To further spread the load of the bolt and prevent things from digging into the leg, I used a large-diameter washer. 

In the upside-down orientation, from bottom to top, the order goes 

1. Large washer
2. Split lock washer
3. Nut

With these over the stem of the castor, you can screw the wheel in adjust the wheel to desired height and tighten the nut to the lock washer.

If you’d like at this point you can apply your finish of choice. I’m still learning a lot about finishes and I wanted to try something natural and easy to fix/reapply so I used pure tung oil. I applied it in a very thin coat with a rag.  From my understanding, the downside of pure tung oil is that while it can protect from water with 5 or more coats it would never provide the protection of a film finish and it takes a while dry in relation to tung oil finishes with additives. 

Woodcraft’s site has some good advice: 

“Yellow birch takes all clear finishes equally well and holds paint nicely. For even staining, though, you’ll first need a wood conditioner or two sealer coats [possibly dewaxed shellac] before staining to reduce blotching. Dye stains are a better choice. The wood’s close grain doesn’t require filling. Because yellow birch’s grain closely resembles cherry, mahogany, and walnut, you can transform it with by stain as furniture and cabinet manufacturers have done for decades.”

Overall, I am very happy with how the desk came out, It is extremely solid and I am satisfied with my integrations of the threaded inserts and hardware. Aesthetically, It looks like it's got some history, and it does, so I'm ok with that. Personally, I'd rather have a piece of furniture that doesn't limit what you can use it for than something you'd be too afraid to damage. I'm sure I will work with reclaimed doors, birch, and threaded interests more in the future. There are a few things to take away from the experience.

What I Learned and Improvements

1. If I had started with 2 by material it would have saved me a ton of time in laminating boards.
2. I left the underside of the door untouched to show the transformation but for better glue adhesion. I should have scraped the finish off of the surfaces I glued. 
3. I still have trouble trying to sand things without going through the veneer :/
4. For a more polished look, I could have stopped the round-overs on the leg pieces at the point where the joint starts.
5. Originally I had planned to use the same threaded inserts and bolts as I did to attach the top and legs but the threaded inserts shredded the end grain when I attempted to install them into the support. Instead, I plugged the holes with dowels and used 3” screws. I would have done something a little more elegant if I had the time.  
6. I calculated the proper desk height using ergonomic recommendations, but not everyone wants to sit upright at a desk all the time. Next time I want to add some sort of adjustability, If I make something like this, as a gift.

Possible Additions and Further Experiments 

1. I didn’t get a chance to fully finish the top for the smaller side table, I need to do the shaping, filling, sanding, and finishing steps. I will do that when I am back.  
2. It would be fun to further emphasize the wax look with more dents and use different colors, maybe just use paint? Make it look like a used artist's table.
3. If I had more time I would have added accessories like a recessed built-in power strip and chord management solutions.
4. I will try to put more coats of Tung oil on, when possible. 

Thanks for stopping by! I hope you learned something and/or were inspired to make something! Let me know what you’d have done differently!