Repairs page 3

BACK in the 1970s I bought a late 1930s Robot II in quite decent working condition from a general dealer who semi-specialised in cameras, and after a spot of haggling I got a non-working Robot thrown in with it as a package deal. It looked very sad with the covering peeling off and scratch marks on the top plate where someone had taken it apart and forced peg spanner nuts round with a screwdriver instead of using a proper tool. The spring motor wouldn’t wind as the knob just clicked round and round on its non-return ratchet and, rather odd I thought at the time, the lens wouldn’t screw home because the screws in the lens mounting flange had cheese heads instead of countersunk heads. I put it away and more or less forgot about it. Then two or three years or so ago I dug it out, put on my rose-tinted spectacles and decided I could probably restore it. Hah! Talk about where angels fear to tread. Little did I know what I was letting myself in for.
     I don’t know who had tried to work on it, but an appropriate name would be Ima Bodger. For some reason he’d bedded the lens-mounting flange on an uneven bed of evil black sealant nearly two millimetres thick on one side and less than one millimetre thick on the other, so it was sitting crooked. Not only that, he’d put the flange on back to front so that the countersunk holes for the screw heads were underneath, and fastened it with long cheese-headed screws. Presumably the original shorter countersunk screws wouldn’t reach through the bed of black sealant. I found one of the short countersunk screws in the wrong place, holding the spring mounting plate inside (the other three were the proper cheese-headed screws) but what happened to the other two flange screws I’ve no idea. Not only was the lens flange out of kilter and at the wrong distance from the film plane, the cheese-headed screws meant that no lens would seat home against the flange.
     What he’d been trying to achieve I’ll never know, unless he had some peculiar ideas about using a lens with a longer than standard back focus. The other thing was that almost every screw on the camera was little more than finger-tight. In some ways this was a blessing, because some of the slots in the heads were badly chewed. Had they been tight I might have had problems getting them undone.After taking off the lens mount and its bed of sealant the next step was to investigate why the spring wouldn’t wind, so the top plate had to come off. That was simple enough. The motor wind knob just unscrewed anticlockwise, though I notice on my other Robot that it’s held by a screw which has two holes for a peg spanner. The knob for tensioning the spool in the take-up cassette was also held by a peg-spanner screw. I would have had to undo the knob on the shutter release button lock, had it been there, but it was missing. All that was left was one screw with a slotted head and two with peg-spanner heads. Then the top plate lifted off.
     The housing over the motor spring, that also carries the non-return ratchet, was held to the main body casting by four screws. Unlike most of the others, these screws were really tight, and the two flanges at the bottom of the housing were bent downwards. One of the screws was one of the missing countersunk lens panel screws. I began to smell more problems. After the housing was off, the motor spring barrel just lifted out. When I took the end plate off the spring barrel I was relieved to find that the spring hadn’t broken. The inner coil of the spring was distorted, and wouldn’t hook on the winding shaft. The spring, like the springs inside the barrels on antique French clocks, had the temper of the inner coil let down so that it was fairly soft, and I was able to reshape it so it hooked properly on the winding shaft. I made the mistake of taking the spring out of the barrel to do this and then wished I hadn’t. Years ago when I restored antique clocks as a hobby I had a mainspring winder, a little gadget with which you wind the spring up tight and slip a clip on it so it just drops into the barrel, but do you think I could find it? I had to resort to the old idea of winding it in the barrel by hand, starting at the outer coil and working gradually round to the inside. There’s always a danger of distorting a spring by this method, but I was lucky and it went back in OK. A few months later the winder turned up lurking in the back of an odds and sods cabinet in the garage that I hadn’t turned out for years. Oh well.
     As I had the spring out I ran it through a lightly oiled rag before putting it back, but if I’d left it in the barrel I would have just dropped a few drops of clock oil on the coils and let it work in as the spring was wound and unwound. I knew why the spring was distorted when I looked at the other end of the spring barrel. The stop-work that prevents you over-winding the spring was lacking its finger. Stop-work on a spring barrel is a very old idea used on high class clocks. It’s a simple but very clever little device of a finger and star wheel designed to avoid over-winding. It allows you to wind up the spring a set number of turns before the winding knob goes solid. I hadn’t got another finger, and the chances of finding one were small. I suppose I could have made one from a piece of brass, but I didn’t worry about it too much. I decided to take care not to overwind the spring.
     Before going any further I tried to investigate why the flanges on the spring housing were bent downwards. I tried just the spring winding shaft in place without the barrel, and tried fitting the housing. The shaft had more than enough end play. I straightened the flanges and the shaft end play was about right, so that was a mystery that went unsolved. After the barrel was back in position I wound up a couple of turns and tried the shutter release. The capping blades opened rather reluctantly, and the rotary shutter made an attempt to turn but gave up after a few degrees. I could see why. The part that came into view was covered in a viscous black oily substance. The whole camera would have to come apart for cleaning.
Inside, the Robot has a plastic housing which forms the film plane. This was held in four nuts on this model, and I think that’s original because they screw on to special flanged studs, though I’m told some models use screws. As I’d noted when I got the camera, the housing had been cracked and glued together, but it sat down square on a flat surface, and film plane was level when I checked it with a block and curved scriber. The part that had been glued seemed firm, so I didn’t disturb it.
     Back on top, there was a top underplate held by three screws that went down into the brass top plate of the chassis carrying the shutter mechanism. When that was off, and the speed selector knob removed from the front, the inside chassis, complete with the shutter mechanism, lifted out. The whole mechanism was coated with a slimy back substance that looked like molybdenum disulphide compound used as an additive in car engines. The makers of these compounds say they stick to the metal so they last through several oil changes. I’ll never doubt their word. The stuff stuck all right. Getting rid of it was an absolute nightmare. The whole mechanism was dunked in a tub of methylated spirit (denatured alcohol) and left to soak for a few hours before brushing out and rinsing. That helped, so at least I could handle it without getting my hands covered in black sticky goo, but the mechanism was still sticky. I dismantled the capping blades and shutter, and they cleaned quite easily in lighter fluid, so I tried dunking the rest of the mechanism in ordinary petrol. This got rid of a lot more stickiness, but I still had to dismantle parts of it to clean it properly.
It was at this point that I found out about the super degreasing properties of carburettor and injector cleaner. It’s sold in my local auto accessory store in an aerosol can. I don’t know quite what’s in it, but it tells you on the tin to use in a well ventilated place, and not to breathe the vapour, so I use it in the open.
      I was beginning to have doubts about ever getting the thing to work again. I couldn’t find even an exploded diagram of the mechanism, and I’m not keen on taking anything apart until I know how it’s supposed to work, but I pressed on. It was still too sticky to work properly, so I had to guess what quite a few of the levers and springs did. It seemed to be a cross between the mechanism of a small clock and that of a cine projector. In the end, after three false starts, and several applications of carburettor cleaner, I got it figured out, but heed a warning if you ever feel like delving into a Robot. It took me two long evenings of dismantling, cleaning, puzzling and trying things till I got it all working again. I had to make up a couple of spacers to take the place of the camera chassis and the underplate so I could mount the spring housing for checking. It was a lot of work, and I now know why very few repairers, if any, will take on a Robot. Be warned, don’t attempt to take a Robot shutter mechanism apart unless you’ve got explicit instructions, or a lot of patience and an eye for how different parts interact. If it needs cleaning, clean it by soaking. It couldn’t be as sticky and gummed up as mine was. Oil it sparingly, with just a tiny spot of oil on the gear and shaft pivots.
I can give you an overview of what happens when you press the button, but don’t take this as a guide to dismantling it. The shutter is a very thin vulcanite (or similar) disc with a segment cut away. Be careful because it’s easily damaged. And make a note of which way it fits. It will try to work mounted back to front, but won’t succeed.
     Starting with the motor spring wound up, the first pressure on the release button opens a pair of sliding capping plates in front of the shutter which at this stage is covering the lens. Further pressure lets the disc spin to make the exposure. You can watch this if you take the lens off and look in the front. When you release the shutter button, the capping blades close and the shutter disc spins back to its rest position. The capping blades have to be closed for this second action because, as the shutter spins back, the cutaway segment passes behind the lens. Without the capping blades the film would be exposed again.
     At the same time as the shutter spins back, the spring in the motor drive operates the single film sprocket to advance the film. Inside, the film transport sprocket also acts rather like a clock escapement except that when the shutter’s at rest, both ‘pallets’ of the escapement are holding the sprocket. One of the pallets moves out of the way when the shutter release is pressed, leaving the sprocket held by the second pallet. As you release the button, the second pallet moves out of the way allowing the sprocket to turn and advance the film till it’s stopped again by the first pallet which is now back in the ‘rest’ position. The shutter speeds are controlled from the front of the camera by a shaft with a cam on its end. This cam governs the tension of a spring that rotates the disc via a segmented rack and pinion.
     It’s a unique and ingenious mechanism and it’s very well made, but it isn’t like any other camera I’ve come across. Only a clockmaker or watchmaker could have designed it. Heinz Kilfit, the designer, had indeed qualified as a watchmaker and precision tool engineer before he turned to camera and lens designing, which might explain it.
To get back to the repair, now I’d got the mechanism working I began to take heart. I was pleased to discover that the badly scratched top plate wasn’t satin chromium plated, it was a deep-drawn stainless steel stamping. Oh, goody! I was able to buff out nearly all the scratches. Things began to look up. After all the hassle with the mechanism, putting things back together again was relatively easy. I had to search through my junk boxes to find enough screws that hadn’t got chewed heads, but in the end I found enough. I was also lacking the proper dome-headed screw for the shutter release lock but I found a small watch winding button in my box of useful odds and sods and soldered a cut-down screw into it. It isn’t a perfect match, but it’s presentably close.
     The old body covering was in a pretty poor state and didn’t want to go back neatly, but I managed to find some vinyl that’s quite close to the original pattern. I was pleased when I mounted the lens flange and checked the distance to the film plane that it agreed spot-on with the back-focus distance given for the lens on the Schneider web site. I didn’t even have to shim it. More importantly, the crack in the plastic film-plane housing obviously wasn’t affecting it. I checked the infinity setting using the two-camera method and that too was spot on. Pause for a huge sigh of relief.
At long last it was finished (did I hear someone say Thank Goodness!) and I could try it out.
      The results weren’t quite up to the same standard as I got with the other Robot. The pictures were quite acceptable up to 8x6 inch size, but they lacked the bite of those taken with the other camera. Not quite the sort of results a Xenar usually gives. I began to wonder if the crack in the film plane housing was, after all, taking the edge off things. As a check I decided to swap lenses, and found that the lens from the originally non-working camera was the culprit. After close examination with a loupe I couldn’t see anything amiss. No scratches worth mentioning, no dust or fungus inside and no sign of separation of the cemented glasses. I’m wondering if Mr. Bodger had it apart to clean it. It would need an optical bench, and the knowledge to use it, to track it down the fault, and I’ve got neither. Having it done by an optical company would probably cost more than I’d have to pay for another lens.