we made our 3/4 in to a full width - it was pretty easy, just a case of making some longer timber pieces, new foam and covering and moving the hinges
You try telling sarah that! - I'm presuming that you meant her and not me?!!!!!! @Moons dont think I haven't seen your post - I'm just not sure how to respond!
Mines a frame rock and roll bed. I made a sort of ledge and put foam on it to take up the empty bit where there's no furniture. (Sarah fell down it once when she was 'tired and emotional'!) We can fit a cheapo double bed mattress in perfectly which is fine except you can't put the bed into a seat easily.
Most instant solution is to buy a full width, metal framed rock and roll bed. In terms of comfort then the depth of the foam is limited by the constraints of the hinge mechanism to an extent as when it folds into a bed the foams have to but up against each other without a gap. if the foam is too deep and you fold into a seat then the two foams squash up against each other and if too thick then it just doesn't work properly. If you have loose cushions then this is reduced or eliminated but your bed making wouldn't be as smooth as it might be. The earlier westy hinges allow for 5 inch on the seat and seat back and 4 inch on the rear shelf from memory. Later westy hinges...not so good at less than 4 inches on the seat and back and about 2 on the rear shelf. Ok if your going to use a good thick mattress topper but not great if you don't want to carry one around. Problem with early hinges are they are difficult to get in good working order so you will pay £££s. then you are into some joinery work to make the thing. Its worth the effort imho but if you want instant then buy do some research on foams for r+rs and see what each type is capable of.
you got a picture of it? (the bed that is lol) might be able to advise on mods to make it work for you!
I shall nip up at the weekend. The vans back at the farm now. I think my foam and shelf solution quite good but princess and the pea says the bed isn't comfy enough
http://thelatebay.com/index.php?threads/timber-rock-and-roll-bed-using-westy-hinges.34335/ This is using later hinges as i couldnt get any decent earlies!
Ta. Just read it all. Will try get it on iPad tomorrow so is a proper size to look at the photos. Ps top job.