parametric film holder design

Hi All.

In the process of building my own ULF camera, I needed some film holders, but in stead of going straigt for the largest format possible on my camera I am building (55x65cm negative format) i opted to first try smaller sizes. for that i needed a design adaptable to the different film formats I want to try out.

In comes FreeCad and a day or three in quarantine . The film holder is build from PVC sheet material and dibond (plastic sheet with alu top and bottom) back and front. the design is made parametrical tot eh extreme. You can enter the film size, tolerance of the film, layer thickness, side sizes, head and tail sizes and the design calculates all cooresponding sizes to cut, showing a 3d render and separate technical drawings per layer.

1. 3d render
https://photos.simski.nl/_data/i/upl...39b4ded-me.png

2. table with sizes. (sorry metric only...)
https://photos.simski.nl/_data/i/upl...d45d5b5-me.png

3. one of the technical drawings
https://photos.simski.nl/_data/i/upl...b67902c-me.png

4. build test with a VSF* negative
https://photos.simski.nl/_data/i/upl...8bd121c-me.jpg

* Very Small Format

as a light trap for the black slide i adapted the method used by Hasselblad and Mamiya, a strip of polypropylene bent in a v shape. the strip i got from a black paper binder sold here in the netherlands, but any polypropylene sheet should do as long as it is springy enough to close the gap of my 1mm thick black slide.

The test build I made without the dibond material, just the pvc sheet i got from a plastic store a couple of kilometers from where i live.

I've started building a 40x50cm film holder, but that is not finished yet.

This is a test setup of the camera i'm building.

https://photos.simski.nl/_data/i/upl...7edfa3a-me.jpg

It all started with a huge lens i got from a friend, the 919mm/36" f8 Bell & Howell lens with a Fairchild K-38 shutter. this thing is heavy! bellows I scavenged from an old Agfa reproduction camera and extends about 1.70mtr with a film side opening of 55x65cm.

I will first make the film holder, then the focus screen and then the mount for those parts on the camera. It seems the most logical way to do things.

Awesome project! Please keep us updated.