Deardorff had rotating backs in some their larger commercial view or studio cameras. The idea was that you could rotate the film rather than the entire camera to align verticals etc.
You could also use strong magnets to hold the back in place.
Pardon my ignorance.
If your back has a square shape, why don't make it with a slot above, and a slot on the side?
You don't need rotating the back.
You would insert the sheet film from above for a portrait shot and from the side for a landscape shot.
Fixed "guides" would centre the sheet on the lens.
Considering that the back is square, and the sheet film is rectangular, the guides for portrait orientation would not interfere with landscape orientation and vice versa.
Am I missing anything? (never used a LF camera).
Without even a drillpress you're going to struggle building a back whether rotating or not. However...
The Toyo back design is made of folded metal so would be hard to directly replicate but the idea is not. Consider the back to be a square wooden thing which rests in a square recess on the rear standard of the camera. You can put the back in in any of 4 orientations and it will sit in exactly the right place as long as something is clamping it in. Toyos use sliding metal latches similar to the ones that typically hold a lensboard onto the front standard. Steve's idea of using magnets to retain the back is excellent though, especially if the non-magnet side was constructed from a 1.5mm sheet of mild steel.
See this photo. While it's the front of the camera, you can see the sliding bit of metal at the top that retains the lensboard - that's how the backs are often clamped in. Think of the back as being like the lensboard - square thing in square hole and clamped in somehow, though of course the back protrudes from its "hole" a lot further so that you can get film holders in. That's all you need to do.
Here's a Half plate back, before a new screen was installed. It ists on two brabkets at the bottom then gets held in place by two brackets that swing in/out of place at the top. OK this is old style book form but any back can be fitted in a similar way as long as the base part is square The parts would be simple to male but you'd need to make some small drill holes to attach them.
thanks for all the tips.
I've now got a good idea of what my plan is.
The camera back won't be made of thick wood, so I don't need a drill press. I'm trying to keep it as light and compact as possible because it will be coming with me on a month long trip in Sri Lanka, so with this in mind I'd like to keep the back side and it's mate a similar size, or the back bigger if either has to be.
just realised I made my bellows too small to be square, so the back my now not be square, but oblong...
but as long as where they join is square it shouldn't matter right?
edit: scratch all that, of course it's not gonna work...
I think it takes a few cameras before you get it right. I have just started my fourth with numbers two and three not yet complete! You think of new ideas and solve problems as you go.
An example of this is the mechanism to rotate the front and back. For ages this was a mystery to me but after spending some time looking at pictures of cameras, mainly Wistas, I realise now how simple the mechanism is and have it drawn up to be included in the current camera.
It was also quite a help to see Ian's Wista a few months ago. If you know anyone near to you who owns a similar camera, try to have a look at it and get the owner to show you all of it's functions/movements.
My advice would be not to worry about getting it all perfect at first, just make a camera which you can use then learn from your mistakes and make a better one.
If you have managed to make a rectangular bellows then make a simple camera without a rotating back. Put a tripod thread on the bottom and on one side and rotate the whole camera instead of just the back. If you want light and compact for travelling, this might help.
There are so many inexpensive ready-to-use cameras, I wouldn't build one unless it was for a yet unmet need.
But some of us enjoy the building.