Last year I decided to build a medium format camera from scratch (apart from a lens). I had a No1 kodak Junior with worn out bellows but the lens was still good and the shutter working fine. So I starting designing the camera around the lens, starting with a small cardboard storage box as the main body. I then attached the lens to the body and knowing the focal length built the internals, making sure the image was sharp by using a piece of tracing paper held against the temporary film plane. Once I had a good image from let's say 6ft to infinity I could start working on the film transport. This was the hardest part, with four main objectives.
1. To transport film around the camera smoothly but with just enough tension to keep the film from unravelling from the spools.
2. To make sure the film remains scratch free at the film plane/pressure plate.
3. Keep the film flat against the plane and avoid light from fogging adjacent frames.
4. Work out frame spacing (sacrificial roll)
The film plane section was made from thick card with velvet ribbon glued to film contact points. The pressure plate was also thick card with springs attached to a buffer stop looking design which was constructed of small lengths of spruce and painted.
I made a wooden frame with a small slot for each side which ensured the spools remained steady, kept the film aligned and with some velvet added, allowed the film to pass through the slot without injury. The bottom of the spools were sat onto thick card with a dowel protruding. The loose spool was held by a dowel at the top and the take up side I used a clock winding key with a small metal pin at the end to lock it in for winding. The key can be lifted to disengage from the spool and allow the box lid to be removed. Making sure the key could wind on and not allow any light through the hole was tricky. I ended up making a light trap with two bits of plastic cut into a circle with black velvet glued to each. As the key is pushed down to engage with the spool, these two bits of velvet make contact and no light can get in. Some reinforcing of the box was made with thick card.
I was happy to find that camera worked great first time. The film does get slightly crinkled along the top edge at the beginning but not enough to damage the negative. Attached are some photos of the camera and basic scans (a little contrasty).
A fun little project made at the dining room table using a cardboard box, thick card, small lengths of spruce, black velvet ribbon, glue, a hacksaw and a WW1 era kodak lens.