- By following a specific set of instructions, and meeting high production standards, students will be forced to improve accuracy with respect to print-reading, measurement, machine set-up, and assembly.
- Students will also develop an appreciation of the importance of using jigs and fixtures in the manufacturing process.
- Students will also develop skills in problem solving, organization, and teamwork.
- Let the students build the project without jigs first. This really helps them understand the usefulness of taking the extra time to make a jig.
- Take the time to make easy-to-use jigs. This is important for SAFETY, and for longevity. A poorly designed jig will be misunderstood and misused by students. Trust me, nothing is fool proof. Someone in your class will find a way to ruin your best creation.
- Use a log-sheet of some sort. The students need a way to track their progress.
- Have a good storage system in place for project work, and stress the importance of not wasting materials. I evaluate groups on their quality control, and efficiency. Because of this, you will find that groups will try to hide their mistakes, and grab some more lumber, or even other group's completed work.
- Stress the importance of problem-solving. To try and detract from the possibilities of the above mentioned step, I remind students that I'm equally impressed by their ability to problem-solve and document their mistakes and fixes. For example: Some groups might cut an arm piece too short. Could it be saved and used for a leg?
- I have yet to create assembly jigs. I have found that despite my best efforts, there are very few groups that will produce accurate enough pieces to make assembly jigs worthwhile. Even a sixteenth of inch difference at the table saw, will cause problems when it comes to assembly.
Step 1: Material Selection & Preparation
- avoid knots, splits, and cracks
- make sure that all pieces of their chair are close in in grain pattern and colour
- ensure that joiner fence is square, so that edges are accurate
- ensure that boards are planed to a thickness of 3/4" and cut to a width of 3-1/2"
- ensure that end cuts are square
- make sure that they have the correct number of pieces for chair
- BE SAFE!!
Step 2: Layout
- 6 of the pieces will be 18" in length. 3 are for the arms, and three for the back rest.
- Trace both ends of the curved template on 3 pieces for the arms.
- Trace the curve on to one end of the two outside back rest pieces, as well as the two pieces that will be used for the legs.
- The 4 seat pieces will be cut to a length of 12-1/2" on the mitre saw. Make sure that students use a stop block so that all pieces are exactly the same length.
- The final 2 pieces are for the front legs, and they should be cut to a length of 12".
- Cut the curves on the band saw. Make sure to cut as close to the line as possible without going over it.
Step 3: Sanding the Curves
It's important that you don't sand the ends of the arms so that the length ends up being less than 18". I find that students often get carried away when they sand because it's so much FUN!
Step 4: Cutting the Legs
- Start by clamping the first leg into the base and lining up the jig on the left side of the mitre saw.
- Cut only as far as you need to go in order to cut through the leg. You'll see from the pictures, that some of my students have been slightly more ambitious.
- Once the first cut has been made, the jig gets flipped around to the other side to complete the second cut.
- It's important at this stage that the line on the jig is lined up with the convenient laser on this particular mitre saw.
- The goal here is to make two identical legs. Make sure that the curved section of the leg touches the edge of the jig before it is clamped in place.
- If you're building this project for the first time, the appropriate measurements for laying out these cuts are available on the PDF plans.
Step 5: Router the Edges
- I use a chamfer bit installed in the router table.
- I raise the bit about 1/16" above the table.
- Make sure to do both edges of each piece.
Step 6: Customization
If you don't have a CNC, you can invest in some letter templates for your hand held router, or even wood burn some designs on the front. Heck, you don't have to put anything on there at all.
Please remember to put your design on one of the seat pieces that is 12-1/2" long. Again, pick the nicest piece, as this will be the one that everyone notices.
Step 7: Assembly PART 1 - the Legs
- Put the legs in the template making sure to put the nicest side face down.
- Make sure that the curved edges are touching the side of the jig.
- Make sure the you used the 12" long pieces and not the 12-1/2" long pieces.
- Countersink three holes for each leg.
- Use 1-1/4" screws to attach the legs.
- I sometimes make students use a screwdriver so that they don't over drill the screws. Some kids can get carried away with a drill.
- Before you proceed with assembly, make sure that both sides came out equal. It's easier to fix a mistake before you put the entire chair together.
Step 8: Assembly PART 2 - Attach the Seat Pieces
- Each of the seat pieces must have 4 countersink holes drilled 3/4" from the top edge, and 3/8" from the ends.
- This can be laid out by hand and drilled with a drill
- This step can also be more accurately performed by setting up a jig on the drill press. This saves you the time of marking out each piece, and also ensures that students will not countersink too deep.
- Start by screwing the name plate to one of the leg assemblies. Make sure that everything is held tightly in place. NO GAPS!!
- Continue with the other leg assembly.
- Next you'll add the first seat piece. Countersink holes are in the same position.
- Continue with the remaining seat pieces making sure that the gaps between each are consistent. I often provide a spacer for this step. The space should ideally be between 1/8" and 1/4"
- When all of the seat pieces have been attached, check the chair again for accuracy. It should sit flat on the table. Make sure you test on a perfectly flat surface.
Step 9: Assembly PART 3 - the Arms
- Choose the arm piece that is the least attractive of the three. You want to use it for the back.
- Set you table saw to an angle of 70 degrees.
- I highly recommend using a jig for this step. SAFETY is so important and you have a difficult time pushing that round curve safely through the saw with a push stick.
- Use the jig to set the position of the fence. Again, remind students that you don't want them to cut your jig smaller each time. Mine's had a few trims over the years.
- Clamp your back arm piece in the jig with the best side up, and complete the cut.
- Use the arm template from before and trace the countersink holes on the bottom side of the piece.
- Countersink each hole.
- Use the arm assembly jig to match up the curves of the arm pieces. Complete one side and then continue to the next, making sure to hold the pieces tightly to the jig.
Step 10: Assembly PART 4 - Attach the Arms
- The exact measurements are listed on the plans. Again, it's hard to design a jig for this step because you get so many slight variations at this stage.
- The positions of the screw holes should be marked on the top of each arm and countersunk.
- You can then position the arms in place by lining up the light pencil lines.
- Hold it tightly in place and install the screws.
- In the last picture of this step, you'll notice that I made the mistake of laying out the countersink holes in the wrong position. Please don't repeat my blunder. I think I got distracted by all the photos I was taking during this process.
- Problem solving time......
- This was solved before moving on to the next step.
Step 11: Assembly PART 5 - Attach the Back Pieces
- Hold the first piece so that its bottom edge is flush with the bottom surface of the seat piece. This will help you determine where the countersink holes should go. Again, I don't provide an exact measurement for this because there end up being slight variation among the groups.
- Line up all three back pieces and square a light line across to layout the countersink holes. Each hole should be 3/4" from the edge, and there should be 2 holes per piece.
- Each back piece also needs to be countersunk on the opposite side of the board along the bottom edge.
- Position the first back piece in place and use a square to make sure that it's standing straight up.
- Screw it in on the front side, and then flip the chair over and screw the back screws in place.
- Repeat the same steps for the opposite side of the chair.
- After installing the second back piece, use a tape measure to ensure that the remaining gap is the same at the top and bottom. If it's not, you'll have to do some problem solving to help disguise whatever mistake has been made.
- Finally, install the middle back piece, ensuring that the gap is consistent on both sides. Get it right the first time, because it's hard to correct if you do it incorrectly.
Step 12: The FINAL PRODUCT
Step 13: Future Plans....
Anyway, we have made chairs for twins before, which inspired me to draw up a new set of plans for a double chair.
Who knows what kind of cool things my students could be making in the future? Wink, wink, nudge, nudge, SHOPBOT
I currently teach woodworking, animation, set design, tech design, and integrated technology at the high school level. I'm not going to lie.... my students would benefit from this BIG TIME!!!