We have had a couple of enquiries about the mirror we made for use after my eye operation. So I wondered if it would be helpful if I posted the details here for anyone to see who may be trawling through the net looking for such a device. If you are one such person and need any further explanation please feel free to ask in the comments section at the end of this post. I will be notified by email.
There are some photos at the end but they are not of the best quality I’m afraid.
The dimensions of the device we made are as follows, to fit on the chair we hired, though the only critical thing is the angle between the two mirrors: the mirror sizes can be altered somewhat to suit your own needs. You may wish to draw pictures, or if you need to email us for further clarification, please do.
Imagine a sheet of paper folded in half along its longer dimension – so that it forms a long narrow shape – and then allowed to open again partially, so that the two strips are still joined along one long side but their other long edges are well apart. Viewed from the end, the paper now makes up two sides of a triangle with the third side missing: the two sides of the triangle formed by the paper should be of equal length, and the missing side – the gap between the free edges – will be shorter in the finished article. The mirrors will be fitted on the inside of the imaginary paper, reflecting into each other, and you will look through the (shorter) open side of the triangle.
To make the device you will need to use wood or sheet metal instead of the paper: we used plywood as being easiest to work.
Our pieces of mirror were each 7 inches (7”) wide and 14” long. Get the glass cutter to smooth off the cut edges – that makes everything a lot safer!
We used six pieces of plywood altogether, some nominally 6mm thick (quarter of an inch, ¼ ”) and the others nominally 10mm thick (three-eighths of an inch, 3/8 ”). These thicknesses are not critical: they were convenient, and we had the plywood already. Whatever you use, the thicker pieces need to be thick enough to accept the screws which hold the whole thing together.
The six pieces for our version were:
two pieces each 8” x 15” and ¼” thick – let us call them pieces A and B
four triangular pieces each with two sides 7” long and the third side 5¾” long, all 3/8” thick – let us call them pieces C, D, E and F. It is important that all four of these pieces have the same angle between their two 7” sides.
Set pieces E and F aside for the moment: you will need to cut them down later on, so that they can be used to hold the mirrors in place, but you will have to assemble the rest of the device before you can do that trimming.
First of all, screw piece C along one of the shorter sides of piece A, one of the 8” sides, so that if piece A is lying on the table piece C stands up vertically at one end. Position piece C so that one of its 7” sides lies along one of the 8” sides of piece A, with most of the extra one-inch width of piece A sticking out beyond the apex of the (vertical) triangle formed by piece C. This will leave the rest of the ‘extra inch’ – say about ¼” – sticking out beyond the broad end of piece C. Thinking back to the piece of paper, that means that about ¾” sticks out beyond the fold, and the other ¼” sticks out beyond the point at which the missing side meets one of the real sides.
Now screw piece D onto the other 8” end of piece A, to match. You are going to take the screws out again later so that you can put in some glue, so they do not need to be screwed up very tight yet – just enough to keep everything steadily in place.
Next, screw piece B onto the ‘free’ sides of pieces C and D, but this time positioned so that one long edge of piece B butts up to the sticking-out strip along piece A – the strip that is about ¾” wide, running between the apexes of pieces C and D. This should give you a neat joint, still with a strip sticking out, and at the same time some spare wood sticking out beyond the broad ends of triangles C and D. One of the broad end ‘spare wood’ strips will be almost one inch wide, the other only about ¼”: this does not matter for the moment.
It should now be possible to slide the two pieces of mirror in neatly along the inside faces of pieces A and B, butting the mirrors together along the inner joint (what would be the fold in the sheet of paper model). Depending on the way you have cut and positioned the pieces, and how thick the mirror glass is, the outer edges of the two mirrors should reach almost – but not quite – to the corresponding edge of piece A, and towards the edge of piece B. If need be, try butting the two mirrors together the other way round, to see if that fits more neatly. When you are satisfied, mark up the edges of pieces A and B and trim them so that each has just a little edge of plywood left to protect the edges of the two mirrors: exact dimensions are not important. You may need to unscrew the four pieces so that you can trim the edges: if so, make sure you know which pieces fit where, so that they can go back in the same places!
If everything fits OK you can now glue the edges of pieces C and D to pieces A and B, and tighten up the screws for the last time. We did not use any glue or screws along the butt joint between sheets A and B – there is no need.
You will eventually need to glue the two mirrors to the inside faces of pieces A and B, but before that cut down pieces E and F – the two that you set aside earlier on – so that they will fit neatly along the inside faces of pieces C and D, and will hold the mirrors in place: you will need to cut off the apex ends of pieces E and F so that they can fit in, and also cut down their broad ends to leave a neat match alongside the edges of pieces C and D when everything is in place. We held pieces E and F to pieces C and D with a single screw each, put in from the outside (through pieces C and D, screwed into pieces E and F: use screws that just do not stick out beyond the plywood on the inside faces). We did not use glue as well as those two screws, in case a mirror has to be replaced in the future. However, we did use spots of glue between the backs of the mirrors and the inside faces of pieces A and B: pieces E and F will prevent the mirrors from tipping or falling out, but the spots of glue are needed to make sure the mirrors cannot slide out. We also put adhesive tape – what we call duct tape over here – along the outside edges of the mirrors, to protect the edges and as a second defence against sliding out. Take care if you run your fingers along the duct tape when sticking it down – that’s when you will find out how well the glass cutter smoothed the edges! The duct tape shows silvery-grey in the photos: we did not bother to paint any of the woodwork.