D.I .Y. Rostrum – Part Three

The Filmcraft 80 Rostrum is suitable for 8mm cameras and light 16mm cameras. In the final part David Jefferson describes the construction of a glass platen.

The platen glass holds the artwork and cels flat for filming. If it is to accommodate various thicknesses of artwork, a simple hinge system would not work because thick artwork would stop the glass going down level. A method had to be devised to allow the glass to find its own level. This is achieved with a double hinge system. There is an outer framework and the glass hinges within this.

It is necessary to support the glass in the open position while you change the artwork. This is done with a sprung arm that is normally sold for furniture cabinets. The spring in this is strong enough to hold up the glass, and when the glass is in the closed position the arm exerts a small amount of downward pressure. The use of the spring arm requires a strongly constructed outer framework.

I used 3/4 inch square Adex Speed-frame for the outer tubes, ½ inch square tubes to hold the glass and ¼ inch steel threaded studding enclosed in ‘/2 inch round alloy tubes for the cross bars, as shown in the diagram.

The back hinges were made by bending steel strips to the required shapes and then drilling the holes. I bent them cold by putting them in a strong vice and hitting them with a heavy hammer.

The glass is glued to the metal supports with Araldite. Follow the instructions on the glue packet for this. The surfaces must be perfectly clean. The parts of the metal that are to be glued to the glass should be rubbed down with emery paper. Wipe both surfaces with meths to clean off any grease. I held the parts together with small clamps while the glue was setting. Use off cuts of wood to protect the outer surfaces when you do up the clamps.

The hinges and the spring arm are attached to the wooden base with bolts going right through the wood. Screws do not give a strong enough hold for this.

You should now have enough information to build your own rostrum. You can adapt the methods used to suit your own resources. Over the period of time I was making rostrums for sale I made changes to them to find more efficient ways of constructing them. I decided there is no quick way to hand-build a rostrum in a small workshop. You need to work to a high degree of accuracy if it is to work well. However, there are a number of ways of achieving the same results with different methods, so if you can not obtain some of the materials I used, a little bit of experimentation will find an equally good solution. I wish you luck with your rostrum building. Let me know how you get on and if there are any questions, please write to me at Animator and I will answer them in a future issue.

Printed in Animator Issue 16 (Summer 1986)