The other day while doing something far and removed from working in my shed ( yeah i can multi task it seems!) I figured out how to do it....
What you need:
Length of 2 x 4 framing timber
Length of timber ( timber to cut your edges from - i split cheap 1.5 planks with band saw.)
"head set" bolt from a bicycle ( thats the one in the centre of the handle bar stem)
Drill and bits
Combination square / square
What its very useful to have;
Step 1: Construct the Back Board
After marking these dimensions up on a sheet of 7mm ply, i cut it out with the skill saw and squared up the edges on the jointer.
Using the band saw (luxury) i split some cheap form wood (cheap rough swan timber)- in too 3cm x 2cm wide strips, placing the first two the fully length of the back board,(See picture 2 (e) and (b)) clamping and gluing with wood glue over night.
Next i did the same with the two shorter end lengths (picture 2 (a) and (c)) these being butt jointed between the first too. (see picture 3)
Step 2: Find Corner Centres.
Using your square with the blade parallel to the inner edge of (c) and 90 degrees across the edge of (b) as shown in picture 4 - scribe a line. (black line)
You have formed a square between the black line and the end of the long edge.
Now split this sqaure by drawing in the two diagonals (green lines in picture 5) from each corner of the square
The intersection of the green lines is the drilling centre for the hinge pin.
Repeat the process for the opposite edge in picture 2(e)
Step 3: Hinge Pin
This is where a drill press is the best option, so that you can drill a hole that is exactly 90 degrees to the timber..... ( good luck if you are using a power drill..)
Place the bottom edge in a drill vice to keep it the edge 90 degrees to the drill (see picture 6)
Now using the center you made in the last step, (picture 7) drill about quarter the length of your head set bolt or the length of the drill bit which come first... on each side.
Then prepare the bolt;
Place the head set bolt in a vice and first cut the head off, then cut it in halve.(Picture 8)
Now place each halve in the holes that you have drilled and tap in to place (see picture 9)
Step 4: Hinge Bearers
In my case the framing of the garage is small (cheap) and i have no desire to pepper it with holes, so i figured a method of clamping it between the top plate and roof - ( picture 11 for your interest)
Once you have figured out how far out from the wall you want your board, add at least 10cm to this and round off the ends (see picture 12 (2)) (best done held together on a band saw so they are the same.)
Then place your bearers up in position and mark with a notation representing the inner most face( the edge facing the other) and clamp them so the inside faces are outer most.( see picture 12)
Using a fine drill,P (say 3mm) drill a pilot hole at your required centre - right through the upper most bearer in to the one below.(picture 13)
Un clamp them, and put the top one aside, and continue to drill the pilot hole right through the bottom one on its own. ( picture 14)
You now have matching centres.
Step 5: Hinge Pin Holes - Bearers
Place the drill bit in the drill press and place each bearer with the inside face up individually on the drill table. Adjust your drill press depth so that the bit at full depth doesn't exceed halve the thickness of your bearer ( see picture 15)
Now drill each hole - (being careful to do so only in the inside face - so that when the bearers are placed in their positions to mount the two holes are facing each other) ( picture 16)
Fix the first bearer in position by what ever method you are using, then take the back board, push the hinge pin in to the hole on the first bearer,(picture 17) place the second bearer hole over the opposite hinge pin, and then place and secure the bearer in place...(picture 17 a)
Step 6: Fit Out
The next step that I haven't completed yet is to set the roof attachments.
in a past version i simple fixed a length of bicycle chain to the rafter above were the bottom end will swing up and a large screw with the head removed in the back board. which i just hooked in to the chain.
or you could fix a little pulley in the roof and have a string that you pull it up with and then tie off.....
Pictures to come when i compete this step.