Mid-Centruy Modern Chair

I have this beautiful mid-century modern style couch. I thought it would be nice to have an accent chair that stylistically matches my couch. Here's how I built it and what I learned on the way.

Design

When planning to build a piece of furniture it is important to first create a visual representation of what you want to build. Having recently started to learn Fusion 360 by Autodesk I decided to design my chair using this software. While I'm not going to walk through how I used Fusion 360 to design the chair I would like to emphasize that this step is crucial to designing a new piece of furniture for several reasons.

1. Having a visual representation helps you to see if the proportions are right.
2. Design the chair digitally in 3 dimensions can help you start to form an idea of how to build the chair.
3. You, of course, need something that you can constantly reference to make sure you are cutting everything to the right dimensions.

Plan

With a design created the it is good practice to write out a plan of procedure. This plan usually ends up being improvised upon during the build process but it is helpful to think through it first so that you have an organized and clear procedure to start with.

1. Mill frame lumber to size
2. Mill edges to thickness and width
3. Assemble top and side frames
   1. Mark and drill holes through top and bottom frame pieces
   2. Screw frames together
4. Assemble back panel
   1. Attach front ply
   2. Attach back ply
   3. Cut edge pieces to final size
      1. Cut right and left edges to frame length + .5”
      2. Cut miter on top ends of side edge pieces
      3. Cut top to fit
   4. Attach edges
5. Partially assemble side panels
   1. Attach inner panel
   2. Cut edge pieces to final size
      1. Cut front edge to frame length + .5”
      2. Cut miter on top end of front edge
      3. Cut top to fit
6. Attach sides to back
   1. Clamp sides to back
   2. Pre-drill holes for screws
   3. Screw side to back
7. Assemble bottom panel
   1. Assemble frame
      1. Cut front and back lengths to fit
      2. Cut side lengths to fit (make sure to leave .5” at front for edge piece.)
      3. Cut leg brackets to size
         1. 4” x 4” right triangles
         2. Drill holes for screws
         3. Attach brackets to frame
   2. Attach ply Attach edge piece
   3. Attach bottom to sides
      1. Clamp bottom to sides
      2. Pre-drill holes for screws
      3. Screw bottom to sides
8. Attache outer ply to side panelsApply
9. Attach legs
10. Apply finish
11. Sew cushions
12. Enjoy!

As we proceed you'll see that I have improvised on this in a few places.

There's nothing more frustrating that having to run to the local hardware store or regional lumber store multiple times because you didn't buy the right part or you didn't buy enough lumber. To help avoid this you can use this handy materials list! Note that when I give dimensions for lumber I will always give them in the order of thickness x width x length.

Lumber

• 2 sheets 1/4" thick 4' x 8' white oak plywood
• 2.25 board feet of 4/4 rough sawn white oak.
  • Your local hardwood supplier should be able to help you figure out how many boards makes up 2.25 board feet. I ended up buying two boards that were 4/4" x 4ish" x 96".
  • If you'd like to learn to calculate board feet on your own see this.
• 8.25 board feet of 8/4 rough sawn poplar.
  • Note: I used 2x4 lumber instead of poplar and I regret it. Some of the boards warped as I was cutting them to size. The convenience and savings was NOT worth it.
• One 3/4" x 2' x 4' sheet of plywood like this.

Hardware & Other Materials

• 4 legs: I bought mine here. I ordered the legs with a bolt in the top end so that I could easily attach them.
• Screw-on Tee Nuts: These will be used to attach the legs to the chair. You can find them here.
• A box of screws
• A bottle of wood glue
• 15 - 1/4" x 2 1/2" lag screws
• 15 washers
• 15 lock washers

Upholstery Supplies

• 2 pieces of 5 inch thick foam 24" x 29"
• One roll of cushion wrap. You can buy it here.
• 3 yards of your choice of 54" wide upholstery fabric. I used this.
  • Note: try to buy your fabric in person as it is very helpful to see the actual color and feel the texture before buying.
• 1 can foam adhesive which you can buy here.
• 2 spools heavy duty thread

We'll start the build process by first preparing the lumber for our frames.

The final pieces of lumber that you will need for the frames are as follows:

• 4 - 1.25" x 1.75 x 29.25"
• 9 - 1.25" x 1.75" x 15"
• 2 - 1.25" x 1.75" x 31"
• 2 - 1.25" x 1.75" x 27.5"
• 4 - 1.25" x 2" x 26.75"

The process for this goes as follows:

1. Plan out your pieces to maximize board usage.
   • Pieces that are the same length can often be cut from the width of one board if the board is wide enough to do so. This will minimize the amount of length cuts you will need to make (see the next step).
2. Cut your frame lumber to rough length.
3. Using a jointer, flatten one face of each board.
4. Now take each board and put the flat face against the jointer fence and joint a straight edge. Repeat for each board.
5. With a flat face and a straight edge that a square to one another you can now cut your boards to rough width on a table saw.
6. Next take your boards to the surface planer to do two things.
   1. Flatten the face that is still rough and cut the boards to their final thickness.
      • Note: To help prevent warpage I recommend that once both faces are flat that you alternate which face is being cut. Ideally each face has been cut the same amount of times.
7. Use the jointer to cut your pieces to final width.
   • Note: You can stack the boards together to run them through the planer. This speeds up the process and helps boards that aren't very thick to be more stable as you run them through on their edges.
   • Note: The same advice applies to edges as faces. Alternate cutting opposing edges.

With your frame lumber cut to rough lengths and square you can now start building your frames. This is how I did it.

Cut lumber to final length

1. Make sure each board has one end that is square to the faces and edges.
   • We're not cutting to final length just yet so cut off as little as possible.
   • Once cut check the squareness
   • I like to mark the square end with an "X" so that I know which end to put against my stop block.
2. Using a cross-cut sled or a chop saw put a stop block at the length you need
3. Put the marked end against the stop block and make your cut.

For the frames you will need to following pieces:

• 4 - 1.25" x 1.75 x 29.25"
• 9 - 1.25" x 1.75" x 15"
• 2 - 1.25" x 1.75" x 31"
• 2 - 1.25" x 1.75" x 27.5"
• 4 - 1.25" x 2" x 26.75"

Assembly preparation

I assembled my frames using screws and butt joints as it was the quickest and cheapest option for me.

Note: The assemble process in the pictures doesn't follow exactly the process I'll explain below because I decided after having assembled my first two frames that I wanted to add a center piece to provide more stability.

Here's my process.

1. Mark where to drill the holes.
   • I planned my holes so that I could use two screws at each joint.
   • It's helpful to have a couple combination squares set up to the dimensions you need to mark.
2. Drill holes using a drill bit that is about the same size as the minor diameter of your screws into the long/horizontal frame pieces. These holes will help us drill pilot holes for the screws into the vertical pieces of the frames.
3. Clamp a frame together and make sure that everything is square. Make sure to leave the holes you have drilled accessible.
4. Drill through the previously drilled holes into the vertical pieces of the frame.
5. Unclamp your frame.
6. On the long/horizontal pieces use a countersink drill bit to drill through the previously drilled holes and create a chamfered recess for the screws. If you use a drill bit like this, you'll not only cut a chamfer but the drill bit will also increase the diameter of the holes so that the screws will slide through holes. Make sure that the drill bit you use is the correct diameter for the screws you are using.
7. Repeat this process for each frame.

You'll also need to cut 12 right triangle pieces that are 4"x4" on the sides. Once you've cut the triangles cut about one inch of of one side of each triangle. See the first picture for reference.

Frame assembly

With all of the holes drilled you are now ready to assemble your frames!

1. Clamp your frame together and make sure everything is square. Make sure the holes are all accessible!
2. Screw the pieces together making sure everything stays aligned.
3. Glue and nail (if you have a nail gun) a triangle piece into each of the outer corners and centered in the frame as shown in the pictures. Make sure that 90° angle is in the corner and the edge that wasn't cut is attached to the top/bottom of the frame. See the first picture for reference.

With your frames all ready to go you can start making things look a little prettier. We'll start by adding the oak plywood facing to the back frame.

1. Cut your two panels to rough size on a table saw.
2. Mark which direction is up and which side faces out or in.
   • Wood grain has a natural up direction to it. You can usually tell because the grain will look like it is pointing up. Some people describe this as looking like flames or cathedrals.
3. Apply glue to one side of the frame and then center it on one of the plywood panels making sure the correct face will be on the outside.
4. Apply glue to the other side of the frame and then center it on one of the plywood panels making sure the correct face will be on the outside.
5. Apply clamps generously.
6. Let the glue dry.
7. Once the glue is dry apply painters tape to the end grain edges of the plywood so that the tape is overlaps the edge of the frame beneath. This will help prevent tear out.
8. Use a router with a trim bit to trip the plywood panels to match the frame.
9. Working through several grits (I usually do 150, 220, 320, and 400), sand both sides of the back panel.

Now is a good time to prepare the oak hardwood that will be used to surround the edges of each panel. We'll follow the same process that we followed to prepare the lumber for the frames.

The process for this goes as follows:

1. Plan out your pieces to maximize board usage.
   • Pieces that are the same length can often be cut from the width of one board if the board is wide enough to do so. This will minimize the amount of length cuts you will need to make (see the next step).
2. Cut your lumber to rough length.
3. Using a jointer, flatten one face of each board.
4. Now take each board and put the flat face against the jointer fence and joint a straight edge. Repeat for each board.
5. With a flat face and a straight edge that a square to one another you can now cut your boards to rough width on a table saw.
6. Next take your boards to the surface planer to do two things.
   1. Flatten the face that is still rough and cut the boards to their final thickness.
      • Note: To help prevent warpage I recommend that once both faces are flat that you alternate which face is being cut. Ideally each face has been cut the same amount of times.
   2. Use the jointer to cut your pieces to final width.
      • Note: You can stack the boards together to run them through the planer. This speeds up the process and helps boards that aren't very thick to be more stable as you run them through on their edges.
      • Note: The same advice applies to edges as faces. Alternate cutting opposing edges.

You're now ready to finish the back panel.

Top oak edge

1. At the table saw cut a shallow rabbet on the top and side edges of both sides of the panel.
   
   • This first step is optional but I think it adds a nice visual element. Later on we'll apply some dark stain to this rabbet. This also helps to hide any imperfections that might exist between the oak edging and the panel faces.
2. With a piece of oak that is long enough to span the width of the back panel cut a miter (exactly 45°) on one end.
   • I like to wrap painters tape around the edge I'm cutting to help prevent any tear out.
3. Lay your piece of oak on the top edge of your top panel, align the bottom of the miter with the corner of the panel, and mark the opposite side to fine the short length of the miter.
4. Use a combination square to layout the 45° angle.
5. Using a cross-cut sled or a chop saw carefully cut this second miter.
   • It's best to intentionally cut this long and then to test the fit, cut a little more, and repeat until the fit is perfect.
6. Once the top piece is cut to the perfect length glue and clamp it into place.

Side oak edge

While the glue is drying for the top edge you can cut the side edges.

1. Cut the a miter on one of a piece that is long enough for the side edge.
2. Hold your piece in place making sure to align it with the top piece so that the corner closes completely.
3. Mark the opposite end to determine the length.
4. Cut the piece a little long and then test the fit, cut a little more, and repeat until the fit is perfect.
5. Repeat these steps for both side edge pieces of oak.
6. Once the top piece is securely glued in place remove the clamps and then glue and clamp the side pieces in place.

Now that the back panel is done let's move on to preparing the side panels.

1. Clamp a scrap piece of the .25" oak plywood the the outside face and aligned with the back edge.
2. Clamp the side panel to the back panel making sure to align the bottom edges as well as the back edge of the side panel to the side edge of the back panel. See the pictures for this.
3. Mark the center of width of the side panels frame that mates with the back panel the mark three evenly space holes. These will be where we drill our holes.
4. Using a drill bit that is the same diameter is the minor diameter (the diameter of the shaft, not the threads), drill through the side panel and into the back panel.
   • It's helpful to measure the depth that you need to drill and then wrap your drill bit with a piece of tape to match this depth. Doing so will help you to drill to just the right depth.
5. Once you've done the previous steps for both side panels remove them from the back panel and then use a drill bit that is slightly larger than the diameter of the lag screw threads and drill through the same holes in the side panels so that the screws will slide nicely through.

We're now ready to attach the outer plywood to the side panels.

1. Cut your two ply panels to rough size on a table saw.
2. Mark which direction is up and which side faces out or in.
   • Wood grain has a natural up direction to it. You can usually tell because the grain will look like it is pointing up. Some people describe this as looking like flames or cathedrals.
3. Apply glue to one side of the frame (the side that will face out) and then center it on one of the plywood panels making sure the correct face will be on the outside.
4. This time instead of applying clamps use a few heavy items to press the plywood down against the frame.
5. Let the glue dry.
6. Once the glue is dry apply painters tape to the end grain edges of the plywood so that the tape is overlaps the edge of the frame beneath. This will help prevent tear out.
7. Use a router with a trim bit to trip the plywood panels to match the frame.

8. Working through several grits (I usually do 150, 220, 320, and 400), the plywood faces.

Cut the pieces

1. Attach the side panels to the back panel then rest it with the back down on top of a workbench.
2. We'll need two pieces that are as long as the chair is wide to the inside. These will be the front and back pieces of the frame.
   1. Clamp two scraps of 1/4" plywood to the inner faces of the side panels.
   2. Cut one end square on each piece of lumber.
   3. Mark the length by holding it up to the inside of the frame.
   4. Cut the length a little long, test fit, and then cut again until it fits perfectly between the two side panels.
   5. Do this process for both pieces.
3. Place one piece so that it is lying on the back and then use clamps to hold the other in place so that it aligns with the front edges of the side panels.
4. Square up the ends of two more pieces. These will make the sides of the bottom panel. Use the same process as described above to cut these to the correct size.
5. Add these two pieces to their places and then clamp them so that they don't move
6. The last two pieces will go in the middle and run from side to side. Follow the same process as described above to achieve the proper fit. See the pictures for how it all fits together.

Drill the holes to prepare for assembly

We'll use the same process that we used to drill holes for the back panel.

1. Mark where to drill the holes.
   • I planned my holes so that I could use two screws at each joint.
   • It's helpful to have a couple combination squares set up to the dimensions you need to mark.
2. Drill holes using a drill bit that is about the same size as the minor diameter of your screws into the long/horizontal frame pieces. These holes will help us drill pilot holes for the screws into the vertical pieces of the frames.
3. Clamp the frame together and make sure that everything is square. Make sure to leave the holes you have drilled accessible.
4. Drill through the previously drilled holes into the vertical pieces of the frame.
5. Unclamp your frame.
6. On the long/horizontal pieces use a countersink drill bit to drill through the previously drilled holes and create a chamfered recess for the screws. If you use a drill bit like this, you'll not only cut a chamfer but the drill bit will also increase the diameter of the holes so that the screws will slide through holes. Make sure that the drill bit you use is the correct diameter for the screws you are using.

Frame assembly

1. Clamp your frame together and make sure everything is square. Make sure the holes are all accessible!
2. Screw the pieces together making sure everything stays aligned and square.

A keen eye might notice that this is not actually the next step that I took but I've since realized that drilling the holes through the bottom frame into the side panels is much easier to do before attaching the plywood to the bottom panel (which is what I did, sigh).

1. Mark a line 3/4" in from the top edge of the bottom panel. We'll want to mark this line along the inside length of both sides as well as the back side of the bottom panel.
2. Mark 3 holes that are evenly space along each side and back. I have a hole centered in each side and the back and the other two holes are evenly spaced from the center hole.
3. Clamp the bottom panel in place. You'll some scrap pieces of 1/4" plywood to make sure the spacing is right.
4. Using a drill bit that is the same size as the diameter of the shaft of the lag screws drill through the frame of the bottom panel and into the side panels.
5. Remove the bottom panel from the rest of the chair.
6. Use a drill bit that is just larger than the diameter of the threads of the lag screws and drill through the holes of the bottom frame to enlarge these holes.

Note: when drilling the whole on the back edge of the frame it is helpful to remove the back stretcher of the two stretchers that help support the seat.

As all of the weight of the chair and the person sitting on it be distributed from the bottom panel frame to the legs it is important that the legs are securely fastened to the bottom panel frame.

Prepare The Corner Brackets

1. Start by cutting three pieces of 3/4" plywood to 5" wide and 16" long
2. Glue one face of two pieces and then layer 3 pieces of 3/4" plywood together to form a piece that is 2.25" thick.
3. Clamp the pieces tightly together and allow to dry.
4. Once dry take the piece to the table saw to cut of just enough to straighten and even up the edges.
5. Square up the ends of the piece on a chop saw.
6. At the chop saw cut 4 pieces to form right triangles with sides that are 4" long.

Drill the holes

We'll need a flat spot for each of the holes that will be used to attache the bracket to the frame of the bottom panel.

1. Use a square and ruler to mark out where the flat spots will be cut. These cuts will be like right angle triangles that share the same hypotenuse as the bracket. See the pictures for reference.
2. Also mark a center line from the 90° corner to the center of the hypotenuse. Mark a point on this line that is 1.25" from the hypotenuse.
3. Cut out the flat spots with a hand saw or jig saw.
4. Mark the center of the depth and width of each flat spot that is parallel and closest to each side of the bracket.
5. Clamp the brackets in place.
6. Using a drill bit that is the same diameter is the diameter drill holes through each bracket and into the frame.
   1. Remove the brackets and use a drill bit that is slightly larger than the diameter of the lag screw threads to enlarge the two holes in each bracket.
7. Drill a 1 1/4" diameter hole 3/16" deep the location marked previous on the bottom face of each bracket.
8. At the center of the 3/16" drill a 3/8" diameter hole 1 1/4" deep.
9. Insert and fasten a t-nut into each whole that you have drilled.
10. Glue the sides of each bracket and screw them in place.

You should be quite familiar with this process so I won't write it all out. You can reference steps 5 and 9 for a refresher.

Make sure to sand the plywood before moving on.

If you've followed the steps correctly up to this point the side panels will be attached to the back panel. We'll now cut plywood pieces to fit the inside of the two side panels.

1. Cut the plywood to rough size.
2. Remove the side panels from the back panel.
3. Using double sided tape attach a piece of plywood to the side panel frame that is still open.
4. Using the same method with a router as before, trim the panel to size.
5. If you want to add rabbets to the edges, now is the time. Only the front and top edges need to be done.
6. Remove the panel from the frame and clean off any tape reside.
7. Reattach the side panel to the back panel. THIS IS SUPER IMPORTANT!
8. Apply glue to the frame.
9. Place the plywood on the frame and carefully align it.
10. Since the bottom couple inches of the frame won't be seen I used a brad nailer to hold the plywood in place.
11. Using clamps apply pressure across the plywood so that it will be tightly attached to the frame.
12. Allow to dry.
13. Repeat for the other side panel.

14. Working through several grits (I usually do 150, 220, 320, and 400), sand these panels.

1. Using lag screws (both the plain washers and lock washers) attach the bottom panel to the side panels.
2. Attach the bottom panel to the back panel.

Top of the side panels

1. Cut a piece to ensure that it has a square end.
2. Place it on the top edge and mark the front edge.
3. This line indicates the short length that is created after the 45° miter cut.
4. Use a combination square to mark the 45° line.
5. Use a crosscut sled on a table saw or use a chop saw to cut the miter slightly longer than the line.
6. Test fit the piece, cut a little more, test again, and repeat until the fit is just right.
7. Glue and clamp the piece in place.
8. Repeat this process for both edge pieces.

Front of side panels

1. Cut a 45° on one end of an edge piece.
2. Place this piece on the front edge of the side panel then mark the length.
3. Use a crosscut sled on a table saw or use a chop saw to cut the piece slightly longer than the line.
4. Test fit the piece, cut a little more, test again, and repeat until the fit is just right.
5. Glue and clamp the piece in place.
6. Repeat this process for both edge pieces.

Front of bottom panel

1. Cut one end square
2. Hold this up to the front edge and between the two side edges as much as possible then mark the length.
3. Use a crosscut sled on a table saw or use a chop saw to cut the piece slightly longer than the line.
4. Test fit the piece, cut a little more, test again, and repeat until the fit is just right.
5. Glue and clamp the piece in place.

It's time to apply the finish and bring out the beauty of the wood. I'm a purist and prefer to not stain the wood.

1. Use a gel stain to stain the optional rabbets. (If I'd been smarter I would have done this immediately after cutting the rabbets to make any needed sanding easier.)
2. Using a lint free rag apply a coat of finish to the inside of the chair.
3. Apply a coat of finish to the outside of the chair. Working in this order will help you avoid rubbing up against the chair and ruining the freshly applied coat of finish.
4. Let the finish dry.
5. Use 600 grit sand paper to lightly sand each surface.
6. Repeat the finishing process several times. The more coats you add the glossier the finish will be.

After the the finish has dried you can put it all together.

Attach the legs, place the cushions on it, and have a seat. You've earned it!