Wednesday, November 11, 2009

Cleaning, Stripping and Filling

It has taken about a week, spending one or two hours a day, to disassemble the projector into its component parts. Most of the parts have been stored in small plastic yoghurt containers, carefully labelled.

Now to begin cleaning everything — because every part, large and small, is covered with oil and grime after fifty years. The first challenge is how to remove the paint from the main cast aluminium chassis.

A couple of months back I restored a pair of Pathé 9.5mm film winders and discovered that immersing painted metal parts in boiling water made the paint wrinkle and come loose so it can be easily scraped off with a scraper or screwdriver. The paint has to be kept hot or else it starts to stick again to the metal.

above Here is the cast aluminium chassis with all removable components removed. You can see the poor condition of the paintwork which appears impregnated with oil in places. There is no question of a superficial clean fixing this problem. The paint will need to be painstakingly stripped back to bare metal. Then re-prime the metal and spray with a dark grey hammer finish paint.

above Here is the same chassis after cleaning by immersion in boiling water and manually scraping the paint with a screwdriver. Once most of the paint had been remove that way, it was sanded manually with emery paper. There are still traces of the original black undercoat but the surface is smooth enough for repainting. I’ve begun filling the unneeded holes with two-pack epoxy filler, which then needs to be filed and sanded smooth prior to painting.

above The inside of the cast aluminium chassis after cleaning doesn’t come up too badly, although the paintwork is scratched or discoloured in places. I’ve taken the decision to re-spray these inner surfaces with matt black paint.

above Another view of the aluminium chassis, looking end on. At right you can see the slot where the gate assembly mounts. On the left is the bracket which holds the motor sub-assembly. You can also see the brass or bronze bearings for the main drive shaft (in the centre) and for the axle of the claw mechanism at left. This photo was taken before filling the holes with epoxy filler.

above Preparing the chassis for painting has taken some time. Filling the unneeded holes has required two or three applications of epoxy filler — filing the excess off each time and then filling any small cracks or crevices which are left. The remaining holes and the previously unpainted faces where the reel arms and the sprocket holders go need to be protected during painting. Here you can see masking tape applied to these areas. Small holes have been plugged with bolts or with bamboo skewers with their tapered ends pushed into the holes.

above Here is a close-up of the holes which originally housed the motor and lamp switches and speed-control knob. These controls were removed by my father when he modified the projector in the 1950s and the holes were covered with a metal shim. Here the holes have been filled with epoxy putty and then filed and sanded flat. All is now ready for the painting operation.

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