she needed the postbox to be fastened to the existing steel palisade fencing above a short column next to her pedestrian gate. the problem was that the gap between the palisades did not allow for any of the horizontal letter openings that were available in local shops. could not get a box with a vertical opening.
we had a short discussion around the picture in her head, combined a couple of quick ideas and i went of to go and draw. a couple of design adaptations later and we settled on an idea.
the main construction is plywood that is covered in a product to keep the weather out. the sides are to be clad in aluminium creating a loop at the top to allow bigger articles like news papers to be delivered (gulp - my first time doing this scale of sheet metal work on my own). the exposed edges gets painted a colour that matches the rest of the fence.the box construction was pretty straight forward cutting and gluing. the joints were held in place with some brad nails and clamps till the glue dried. i made a little "tunnel" around the letter opening to help keep water out and make it more difficult to retrieve items from the front of the box. i hope this is sufficient.
the door that covers the opening at the back is hinged with piano hinge to spread the load of the screws on the wood. the door needed to be latched in the closed position, i bought a cupboard latch that would hold the door closed. this latch usually gets operated from inside the the cabinet but this was not possible with the completely closed box. i made a hinged handle on the outside that gets connected via a piece of thin brass rod to the latch on the inside. lifting the handle unlatches the door. this was too much fun to design and make and it works like a charm!after checking that there where no gaps in the joins and sanding the box it got treated against bugs and then coated with "Aqua shield". this stuff seems pretty cool, in the hardware shop product display there is a chipboard box that is coated with this stuff. it was then filled with water and left. there is no swelling in the chipboard and it has been standing like that for months. the shop has actually covered the top of the box with a piece of see through plastic because the water was evaporating... My postbox got coated inside and out.
i painted the box with a green coat of enamel and then started to tackle the unknown. the sheet metal...
i decided that the easiest way to get the curve on the top was to create a "buck". a form over which the material can be shaped. so i cut some circles to the right diameter out of some scrap plywood and cut some notches. i held them together with some hot glue while cutting.
the bending process took some thought since the buck had to be held in place but i could not screw it onto the letterbox in anyway since it would then damage it. i tied it on using tie downs making sure that ratchet is located at the bottom of the box. this worked pretty well to get the preliminary shape. for this i carefully marked all the screw locations on the aluminum and drilled it. all the holes got counter sunk from the outside to get the screws as flush as possible. tricky when working with sheet that is only 1.5mm thick. i then rough cut the this side and fastened it to the side.with the buck in place it got bent over. i used the heat gun and a rubber mallet to provide a little persuasion to the the curve the right shape. i then removed the straps and marked and drilled the other side. ( this makes it all sound so quick! )
the unit got rough cut again using the jigsaw to get as little material possible sticking over the edges.
after a little research online to make sure that it will not damage my tools i decided that the quickest way to the sheet flush with the sides of the wooden box was to use a flush-trim bit in the router. this work very well, taking slow cuts and clearing the bit when it got clogged.
i buffed the outside of the box to get rid of the little scratches on the outside. and gave the whole cladding a coat of clear lacquer to try and protect the shine.
since the box was going to be fastened through the front panel i needed a "foot" to hold it up in the back. i found some scrap stainless, and tried some YouTube acquired blacksmithing skills. and put together a foot that would go under the back of the box, getting fastened to both the underlying column and the base of the letterbox.for the inside i cut and drilled a little piece of flatbar to spread the load of the screw heads.
installation went really smoothly - i really focused on the measure twice cut once principal and it paid off. the box mounted dead straight in the gap! the over all picture was good. the mounting is nice and sturdy and it blends well with the rest of the fence. the numbers where cut with the jigsaw. it felt so wrong leaving the completed letterbox out in the weather like that!
