REVIVING A KOK

Like many of my projects, this one has been a long time in the making. It has taken place over a number of years and proceeded in stages, as I hit snags or found something new to distract me. Various of the parts involved, notably the frame, lamphouse, mech and dynamo I have shown you as I went along. I have now decided to make a further push in the direction of completion; basically this has involved deciding just how far to go in cleaning up and re-painting all the smaller components, having already dealt with the big castings.  I would emphasise that this was a machine so far gone cosmetically as to have nothing salvageable left of the original finish - in general, it is better to clean and polish rather than re-paint.

The start point was 3 partial KOKs in pretty poor condition.

Between the three, there was no decent lamphouse, only one set of optics - condenser lens and projection lens - two gates and two crank handles, but there were three mechs but of course, no rewinds. There was also a dynamo; whether with these machines or acquired separately I cannot now recall. I reckoned I might ultimately get a dynamo model and a mains model out of the three. Over time, I built a lamphouse, re-furbished the dynamo, had the frame and other key components professionally painted, designed a simple rewind and came up with a way of providing a projection lens. At this stage, I decided the time had finally come to push on to completion.

I never cease to be amazed at the range and scope of problems encountered in trying to restore an old projector - these three are probably close on 100 years old - even where, as here, the basic mech was good and the entire thing pretty simple compared to some. Even to strip down and fettle the rather crude frame casting was a lot of work, full of odd corners etc that were really difficult to clean up. Here are some before pix and an after pic of the frame.

The row of pix above is various parts I have had to make or re-paint. Pic 4 has a couple of KOK bits lurking among Vox and Rural bits and pic 5 shows , as well as the lamphouse, the swept-back arm for the top film guide - I had to make this especially well swept-back to accommodate my new big lamphouse. Having done all of this preparatory work over time, I thought it would mostly be a matter of re-assembling the various bits. I should really ought to have known better.

Here is a pic of some, tho by no means all, of the various other bits and pieces that needed cleaning up or painting. A proper nuts and bolts restoration will go even further than I have gone, but I have gone quite a way. I have sanded down screw heads to remove burrs from previous users' exploits, then cleaned out the slot and polished, and much the same with nuts. Springs are especially difficult to clean and de-rust. Many KOKs have problems with the white "rust" or efflorescence that afflicts the castings, due to storage in damp conditions, which causes pitting and lifts the paint. These need extensive sanding down to get a fairly smooth surface for paint and are of course always full of twiddly bits and corners that are difficult to access. Missing parts must be cannibalised or made anew. In short, it is a pretty major commitment of time and effort; OK if that is all you are doing, but I always have more projects than I can shake a stick at, many at similar levels of detail. Methods that may help in cleaning up are described in articles on restoration elsewhere on the site.

Starting fom the basic frame, we next add the two main central shafts, carrying the sprocket and part of the drive chain. As you can see (I have not engaged the gears to make things clearer), the step-up in speed from the large gear via the very small gear then the large outer pulley to the small pulley on the dynamo is very substantial.

The oiling system for the mech is interesting. There are two oil channels under the shiny brass thing on the side of the mech; these are obviously cast integrally. one to serve the claw slide and one for the shutter shaft bearing. Each channel is filled with felt, arranged in the case of the claw slide to poke out and make direct contact. I acquired some thickish felt and suffed it down the shutter shaft hole until I could see it just emerge at the bottom. You will note that the other side of the claw slide appears to be hung out to dry. I wonder if this could cause some sort of jamming and so explain the frequent damage seen on 28mm films.

When it came to re-assembling the mech, it's so long since disassembly that I worked out from first priciples which way round to put the long bolts at each corner that secure the two halves together. They each have a tapped hole one end for a screw and a thread the other end for the nut. One of the fixings is under part of the gate, and all the holes on this face have shallow recesses for the screws or nuts. There is one screw with a flat rather than domed head, to fit under the gate, so it seems all the screw heads are on this face, with the nuts on the front of the machine, where the recesses are considerably deeper. I'm not sure I would put nuts rateher than screw heads in the most visible spot, but ............  I checked on my complete machine and it does seem to be right.

This was about the point where the easy re-assembly illusion began to meet the harsh light of reality. I mentioned I had several mechs, which are easily interchangeable - or so I thought. It turns out that some machines have the fixing point for the mounting bracket supporting the long drive shaft seen in pic 3 above cast as part of the frame, but in others it is part of the mech itself. I tried the shaft from a different machine because something was wrong - the mech was stiff at certain points and the gears growled and ground; not at all usable. Change of shaft didn't work; the cause eventually proved to be in two parts. First, the slots in which the claw frame slides had gotten painted and were stiff, so lots of fiddly sanding etc. Second, the claw was out of line in the gate and the side of one pin was scraping on the inner edge of the sprung gate. There is, I found (eventually) a fairly simple adjustment to deal with the horizontal position of the claw. You may be able to get some idea from pic 2 above - the claw pivots are on threaded pins with a locking nut, so can be slackened on either side while tightening the other and so moving the claw across.

I mentioned that I had only one set of optics, but two gates. It seems that the mech I had had re-painted would not readily accept the second gate, which wouldn't shut properly. This mattered because in the single set of optics I had, the condenser lens was specific to the second gate, having 3 securing screws round the rim to fix it to the gate structure, whereas the first gate, that did work, had four mounting holes, so there was no chance the twain would meet without horrific butchery. So I had to design and make a condenser lens mount from scratch and somehow find something that would serve as a lens. This was a long and tedious process with many trials before I came up with something that would work.

I also experimented with various different lamps and set-ups. I have previously found dichroic mirror lamps to give good results, so I naturally looked at that first as a possible solution to my lack of condenser lens. It did not, however, seem to work with the projector lens I had made up, tho' I haven't tried it with the proper KOK lens. In the end, I plumped for a standard peanut lamp mounted in the usual ceramic base which is in turn mounted onto an aluminium bar (pic 2 above). This bar is a sliding fit in the shaped conduit into the lamphouse, giving simple adjustment of height and horizontality of the filament (pic 1, repeated from before). In order to be able to use at least a 12v 100w lamp without too much heating of the lamphouse I am trying a small computer fan inside the lamphouse itself (see pic 3). 

The way the non-handle end of the crank (pic 1 above) is mounted onto the machine for storage is copied from my complete machine, but at the other end, my complete machine has a sort of spring clip such as those used for mounting tools onto a workshop wall. This seemed to me a somewhat inelegant approach, hence pic 2 above. I didn't feel up to copying the captive, spring-loaded plunger used as a click-on/click-off device, so opted for the simpler solution seen in pic 2, with a non-captive screw with a big knob. Here is the complete thing - you will notice that yet another thing I had to make was a sprauncy new base.

I now have to make up a power supply and figure out a way of wiring it to lamp (AC) and fan(DC). I'm not sure there is room anywhere on the baseboard to attach the power supply, so this may have to be a separate unit with the machine plugged into it somehow.

What I am left with now is the bones of a second KOK, mains model, with most of the basic components that would be hard to duplicate, ie optical system, gate, mech, (small) crank handle, plus a spare mech and frame. I feel I have had all the enjoyment I am likely to get out of thees three machines, so I have in mind to sell these parts as a sort of KOK kit for someone who feels up to the challenge of making a lamphouse and various other components and doing with the kit what I have done with this machine.