How to make a children's picnic table from a single 3.9m (13ft) scaffold board.
Step 1: Roughly Mark Out the Board
You don't need to do this but it will help you visualise and manage the cuts.
You'll need to mark at:
- 2 at 500mm
- 3 at the remaining length divided by 3 (probably around 660mm depending on the kerf (thickness) of your saw blade
Use chalk or a thick pencil - something that won't mark the wood.
Step 2: Accurately Mark and Make the Cross Cuts
I used a mitre saw but you could use anything capable of cutting the board. You'll be making 5 cross cuts.
Step 3: Rip Down the Boards Into Thirds
A tablesaw is easiest for this but you could use any saw you have.
Accounting for the blade kerf, you need to rip them down into three equal parts.
Step 4: Cut One of the 900mm Down to 660mm
Take one of the 900mm lengths and cut it down to match table slat length (probably around 660mm).
Save the offcut and don't worry about bevelling its edges in the next step.
Step 5: Bevel or Round All the Edges
You can either sand or cut the edges to make them feel and look nicer. You don't have to do this step in order to build the bench but I think it looks better and will be less harsh for those sitting it it.
I have used a tablesaw with the blade set at 45 degrees and a belt sander to achieve this with equal success.
Step 6: Cut the Angles to the Legs
Each of the 4 legs (500mm) will need a 20 degree cut of the end to make a parallelogram.
Step 7: Cut the Angles to the Table Stretchers and Seat Supports
Each of the lengths (2x 500mm and 2x 900mm) will need a 10 degree cut to make them trapeziums.
Step 8: Fix the Table Slats to the Stretchers
Glue and screw 6 slats (~660mm) evenly spaced across the 2 stretchers, space the stretchers the thickness of a board (38mm) from the ends of the slats.
Drill 2 holes just bigger than your screws per slat in each stretcher and screw through the stretcher into the slat (don't worry about drilling the slats at all). Use 100mm screws.
Step 9: Attach the Legs
Glue and screw the legs on the inside of the stretchers, again drilling clearance holes in the legs and not drilling the stretchers.
Use screws between 50mm and 70mm long.
Stand the bench on a level flat surface and use the little play in the legs to get them to sit flat and then leave for the glue to dry.
Step 10: Attach the Seat Supports
You can place these at any height but I find 125mm from the top of the support to the bottom of the stretcher works well.
Glue and screw them from the inside after drilling clearance holes in the supports.
Use 50mm to 70mm screws.
You could add a carriage bolt to each of these joints for strength.
Step 11: Attach the Seat Slats
Glue and screw the slats from the underside, again drilling 2 clearance holes per slat in the supports. Align the outside slats to the ends of the supports and use the same spacing as for the table slats.
Use 100mm screws.
Step 12: Fix Seat Braces
Remember that offcut earlier?
Cut that in half (angle the ends of each half if you want) and then glue screw it across the 2 slats on each seat. Again drilling clearance holes in the braces.
Use 50mm to 70mm screws.
This step isn't completely necessary but it uses up the leftovers.
Step 13: Paint, Stain or Finish As You Desire
Now you can cover it in whatever you like.
I'd recommend turning it over and doing the underside first and then flip it and doing the top.