There are many ways of going about making a seat. You can use all separate pieces, or you can bend larger pieces to curve many of its features. There is a lot of room for individual preference and creative design, but here are a few general principles.
Remember that the cardboard support pieces are stronger when the flutes run up and down.
Make sure that there are support pieces under any surfaces what will bear weight. If the seat is large there should be center supports as well as side supports.
Use a liberal amount of hot glue. Work quickly with this glue. Use clamps or prolonged pressure to make sure that the bonds are secure.
Once you have the child’s measurements and a chair plan you will begin building the chair by constructing the seat box. Even if the chair will eventually tip back or have a corner style back, we begin with the basic box.
The Basic Seat Box
The seat box is constructed of 4 pieces of cardboard. In all cardboard construction, you must plan ahead to figure out how the pieces will fit together.
1. Determine the size of each piece of the box by using the measurements for the completed seat and accounting for the thickness of your cardboard. Back and side pieces will be shorter than the measurement for the seat height to allow for the thickness of your material.
Back Piece = A (minus the thickness of the cardboard for the base and top) x B. (Our triple wall corrugated material is about 5/8″ thick but yours may be thinner or thicker.)
Side Pieces = A (minus the thickness of the cardboard for base and top) x C (minus the thickness of the cardboard of front and back)
Top/Front Piece = B x A plus C (add 2 inches to allow for the bend or error). This is one long piece in order to curve the front edge of the seat. This eliminates the corner in the front that might be uncomfortable against the child’s legs.
2. Meaure the pieces and cut them making sure that you take into account the directions of the flutes (or grain) in the material.
3. Push a blunt tool (like the back of a spoon) along a ruler to make an indentation across the top/front piece where you want the bed to be. Turn this cardboard piece over and line up the bend just off the edge of the table.
4. Place the side and back pieces in their proper position on the bent top/front piece. Mark the excess on the ends of the top/front piece and trim. Recheck for fit.
5. Hot glue the pieces together (make sure you place glue at all points where two pieces of cardboard meet one another). Use clamps to make sure that the part that is bent does not open and glue has time to set.
6. Sand box to ensure it is even on all sides.
Modifications to the Seat Box
Cornerback Style Chair (Provides additional support to child’s body):
1. Determine how wide you would like the center panel of the chair to be (typcially smaller than the child’s trunk width).
2. Using that measurement, mark where the back corners of the chair will be, on the top/back of the seat. Meaure, along the back of the seat, from your mark to each corner (these marks should be the same distance.)
3. Mark this same distance down the side of the chair top (this will ensure that you will have 45 degree angles at the bends). Draw the diagonal line across between these points.
4. Extend this line down the sides of the box as well.
5. Saw off the back corners of the box with a hand saw (or a band saw if the seat is low enough to fit).
6. Fill in the back corners with small pieces of cardboard to add stability to the seat.
Chair That Tips Back in Space
Supports children with low muscle tone or who are unable to hold themselves upright against gravity, while maintaining their hips, legs and feet in proper position. Also known as a Tilt in Space Chair.
Wait. Add the back first and then modify the seat.
Chair with a Back That Reclines
Opens the angle of the hips past 90 degrees.
Determine how far back you would like the chair to recline.
Mark the angle of recline on the back of the seat box and cut. (In this case you could have just eliminated the back piece and cut the side pieces to the correct angle before gluing.)
Wrap Around for Back and Sides
If the sides and back are all made out of a single piece, the construction is a bit stronger, and there are fewer edges to cover.
You can bend the piece using the same scoring technique (back of the spoon and fold on edge of the table) that you used to bend the seat piece, or you can cut grooves into your card board to be more precise.
You accomplish this by cutting parallel lines along a straight edge with a box cutter and removing the first layer of corrugation between these lines.
Then fold along these troughs.
The size of your grooves is determined by what angle you are looking to achieve. For a 45 degree angle your groove will be smaller than if you were looking to make a 90 degree angle. (For our 5/8” thick material we allow 3/8” for 45 degree bends and 3/4” for ninety degree bends.)
Creating the Wraparound Piece for Back and Sides
Draw out the following shape if you are making a chair with a basic square back.
Draw the following shape if you are making a chair with a corner-style back.
How to Construct and Attach Back/Side Piece
Draw the shape of your wrap around piece on a large piece of cardboard, using the rules listed above.
Cut out this back/sides shape.
Score the lines where the folds will be and pull out the top layer of corrugation between the scored lines.
Use needle nosed pliers, a chisel, or a screw driver to remove this material.
Bend this piece and fit it to the box.
There may be a bit of excess in the front. Mark and trim this.
Mark a line around the seat. This will remind you not to put glue above this line when assembling.
First apply glue to the center panel of the back piece (be sure to stay under the line).
Once the center panel is glued, apply glue to one side and clamp.
Once that glue is set apply glue to the final side. Squeeze the wrap around piece tightly around the box, ensuring a snug fit.
Put large clamps across the front of the seat for a few minutes to make sure that the bent piece won’t open making a weak joint in the front.
Once you have securely attached the wrap around the next step would be to modify it to tilt in space or create the armrest for the chair.
Modifications for Tilt-In Space Chairs
Typically if the child requires a tilt-in-space, they would also benefit from it being a corner chair.
The following instructions assume that your chair will have a cornerback and be tipped back in space 10 degrees.
Draw the shape of your wrap around piece, using the rules listed above for a corner style.
Use a large piece of cardboard with a straight edge along the bottom.
Ensure the flutes are running up and down.
Draw a straight line (from the bottom up) where you will begin your measurements. It should be as long as A+E (minus 5/8 or the thickness of your cardboard).
Measure the first side of your box (1), using that measurement (plus adding 1/2 inch) mark where the next line will be and draw your next line on your large piece of cardboard.
Next you will make a groove for your first 45 degree bend. Measure 3/8 inch from your last line and then mark your next line. This line will be the length of A+D.
Measure area (2) of the seat. Then mark that distance and draw your next line to the length of A+D.
Measure 3/8 inch for your second bend and draw your line to the length of A+D.
Continue this process until you have made it around the back/sides of the seat box (ending with the measurement for side (5) + 1/2 inch
NOTE: When making a tipped back chair you have the option of having the armrest be parallel with the seat or modifyng your drawing further (same as picture above) to have your armrests parallel with the floor.
To make the armrests parallel with the seat, the height of the front and back of the armrest should be A + E (minus 5/8 inch or the thickness of the cardboard).
To make the armrest parallel with the floor you will have to add the same amount of tip for your chair to the armrest.
Use a protractor to find your angle and then draw a line along that angle from the front tip of the armrest to the beginning of the back of the chair.
Be sure to extend your 3/8 inch groove to account for this change.
Cut out the wrap around piece.
Score the lines where the folds will be and pull out the top layer of corrugation between the scored line. Use needle nosed pliers, a chisel, or a screw driver to remove this material.
Bend this piece and fit it to the box. There may be a bit of excess in the front. Mark and trim this.
Draw a line on the wrap around piece which indicates the location of the top of the seat.
Glue the seat box to the wrap around piece starting in the center and moving out to the sides. Clamp the two pieces together and allow time to set.
How to Cut the Chair to Allow it to Tip in Space
Cut a cardboard piece with one edge that matches the angle of tilt that you would like your chair to have. Example: We want to tip our chair back 10 degrees (from 90 degrees) so we a cut a piece of cardboard that has an 80 degree angle.
Put this piece right up against the back of your seat. Measure how high the front of the seat lifts up off the work surface.
Use that measurement to mark the distance, on the center panel of the back of the chair, from the bottom of the seat up and draw a line across center panel at this height.
Measure the degree of tilt that you want from the bottom front corners of the seat along the sides. Mark these lines.
Connect ends of the side and back lines.
Cut along this bottom shape with a hand saw, jig saw, or a serrated knife.
Sand as necessary to make sure that the chair sits flat on the floor.
The armrests will be the same length as the sides of the chair.
We usually make them between 2 ½ and 3 ½” across (width).
It is always nice to curve the front and back outside corners of these pieces so that there will be nothing sharp for the student to feel and so that the cardboard will be a bit less likely to crush.
The inside front and back corners should not be curved.
Sometimes the back corner needs to have a little diagonal cut across it or a little notch so that it neatly fits onto the side.
Arm Rest Supports
You will want to cut supports to go underneath the armrests.
They should come to the edge of the armrest, without passing it.
Triangular shapes are, easy, quick, and easy to tape, but other shapes work well too.
We usually make two supports for each side.
For larger armrests feel free to make more supports.
Glue the triangular supports onto the edges of the seat.
It is easier to evenly space these supports if you put them on before the armrests.
Glue the armrests on top.
You can cut the slots for straps with a serrated knife or an oscillating tool. We usually make our straps 2 inches wide, so the slots work well when they are 2 inches loong by 1/2 inch wide. The following are some guidelines for placement of these slots.
Slots for Shoulder Straps
These strap slots should be at the child’s measured shoulder height.
The inside corners of the slots should be a little further apart than the imagined width of the child’s neck.
These slots should angle down slightly to match the slope of a typical person’s shoulders.
Slots for the Chest Strap
These slots are vertical.
The height should be half way between the seat and the shoulder slots and the seat or pelvic slots.
They should be a little closer together than the width of the child.
Usually these straps are the typical 2 inches by 1/2 inch, but sometimes a wider strap is recommended to wrap around the child’s chest. Then this length changes accordingly.
Slots for Pelvic Belt
Since the objective of the pelvic belt is to hold the child all the way back in the chair, the slots for these straps should start right at the corners at which the seat, sides, and back come together.
They should be angled to 45 degrees so that the strap neatly wraps around the child’s lower trunk.
Slots for Headrests (not pictured)
Headrests can be made out of firm Romex electrical wire, foam, and vinyl.
These side cushion-type headrests require two vertical slots that are about 4 inches long and 1 inch (or a bit more that 1 inch) wide.
The bottoms of these openings are ususally about an inch above the top of the shoulder slot.
The insides should be a little further apart than the width of the child’s head.
Usually cutting them right outside the vertical fold line works well.
Slots for Foot Straps (not pictured)
Mark where the child’s feet will be placed on the footrest.
Straps should wrap across the instep and be shoe-width apart.
Smaller children may need narrower straps.
The slots can be 1 & 1/2 inches long rather than the typical 2 inches.
The purpose of the base is to make sure that the child does not tip back or to the sides.
For a basic square chair, the base is the same width as the distance between the outsides of the armrests.
The depth of the base is the same as the depth of the chair plus about 2/3 inches of that depth.
If the child needs a footrest then the base will extend out in front of the seat.
Measure and cut the base using the rules outlined above.
Round all of the corners.
For a square chair center the chair on the front of the base. Outline the base of the chair where the border for the glue is and glue the base into place.
For a tipped back chair leave the necesary space for the foot and center the chair. Outline the base of the chair where the border for the glue is and glue the base into place.
Measure and cut a piece of cardboard for the top of the footrest by taking the length of the child’s foot plus 2 inches and the width of the chair.
Make angled support pieces that match the angle of tip for the chair.
Add a support piece to the front of the angle pieces and glue together.
Sand the back of the foot rest to match the angle of the front of the chair.