Rural Sonore

 BB1 BB2 Home Talkie Super Rural




(For Instructions - in French - click here)


I had a serious rush of blood to the head earlier in the year (this is Sep 06) and bought on French ebay 2 Pathe Rural projectors, that had been converted to 16mm, as most of them were. You may recall this was the first of the 17.5 sound projectors, basically an adaptation of the silent machine known over here as the Rex. This Rural never made it here at all; we got the Home Talkie, an adaptation of the French Natan 175 and, very briefly, the Super Rural, known here as the Super Talkie. Clear so far?

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The Rural Sonore is very obviously a converted Rex, especially from the back, with the flywheel looking very much an afterthought. The main lamp seems to feed the sound optic as well. The arm arrangement at the front seems identical to that in the Super Rural/Super Talkie. I have only just noticed that the machine in the Kermabon illustration (click Rural Sonore to see) is different -no rear flywheel. There seems to be instead a large drum, presumably with a flywheel at the back of the projector, in a much more conventional arrangement with a separate exciter lamp. The Kermabon one must be a Mk 2. Or Mk. 1. The pix with blue backgrounds are from ebay.

I seem to have forgotten to take any pictures with the spool arms in place. As you can imagine, I have grandiose visions of re-converting one or both to 17.5. Note that the sprockets are housed in "turrets" attached above and below the mech. These are made of Mazac, which as you know can distort with time. In this case, it causes the bearing for the sprocket shaft to seize up, which in turn leads to stripped gears.

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Actually, I do have a pic with arms - think I pinched it off ebay.

If you blow up the pic, you can see one of the stripped gears from one of my machines (the other machine is fine); the long shaft is driven by the motor and in turn drives both sprockets. The second sprocket shaft is identical to the one shown, but is handed the opposite way. These would have to be re-made by a specialist firm. The third pic shows the claw mechanism. Lots of other problems too - one motor has the ends crumbling - Mazac again - and I am pondering how to make new ones, and of course there is the problem of the cam. Problem is, getting work done by any of the handful of skilled engineers left in this country costs so much. Anyone know someone who does it just for love?

Another problem I have discovered with Mazac is in at least one of the motor ends, or caps, where distortion has caused the motor to become jammed. I have been contemplating for a long time having a go at making a replacement end cap, not least because this is not a problem unique to the Rural - the Vox and Lux also have this problem.

It is not something I undertook lightly, as I simply am not very good at this sort of thing. I have never had any training in metalworking, what little I know is gleaned from books. Either because of astigmatism or some other personal defect, my eye is not at all true and I have great difficulty lining things up precisely etc. I also seem to have no spatial awareness whatever, and those things in IQ tests where you had to rotate a shape always had me foxed. As a result of all this, I tend to work very slowly; I have to figure out what and how to do and go over things repeatedly to avoid (most) of the sillier mistakes. To illustrate my difficulties, I carefully bought a 7mm x 0.75 tap and die to match the thread on the oilers for the Rural motor, then carefully used a 7mm by 1.0 tap, which means I shall now have to make replacements rather than simply re-using old bits.

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Here are the original end caps, both sides, in 1 and 2, together with the putative replacement at an early stage. I decided straight away not to copy the round-ended appearance. A close examination should show you the Mazac cracks and distortion. Pix 3 & 4 show the new end at an advanced stage. It now fits, and I just have to finish off on the oiler holes (see above). Not very pretty inside, tho' this do not matter. You can see I've slightly mislocated the opening out slot on top (only done the one so far) and have broken thru at one point, tho' I don't think it matters except cosmetically.

In order to be able ever to do this again and record all the measurements I've used, I've drawn sketches for my records.

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Once I've finished it, there is then the matter of testing to see if it will work. All sorts of reasons why it might not. A problem I have met before is that there is a point where the wires join the main windings inside where the wires get crimped and can fray or fracture - we're talking a respectable age here - and short circuit or just lose contact. Then the original jamming of the motor might have overheated it and burnt it out. Or the main rotor may catch the windings - space is very tight inside and it would not be that surprising if things had warped out of true over time. This would be a problem as, although motor rewinding is common, it's also costly.

The actual motor bearings are an interesting pattern. Instead of the ball raceRural-Sonore one might Rural-Sonore expect, the motor shaft passes thru a brass bush (see pic), which is held in place by a spring and and a washer secured by screw thru the holes in the motor cap. The main hole thru the motor cap is rounded at the outer end, and the brass bush is pressed against this by the spring. Basically, it allows the bearing to "float" to a degree, presumably to prevent alignment problems.

Nerdistan Celebrates!

There was great jubilation today throughout Nerdistan. People thronged the streets to celebrate the news that the new end cap for the Rural (see above) had been installed and tested and worked fine! This is a major step forward for Nerds!

I tried a new approach on the wires leading from the motor. As indicated below, there is danger from age and brittleness leading to the wires or their sheaths cracking and causing short circuits or even breaks. There was a specific kink point where it looked like this was happening; I thought I could see a glimpse of copper. A while ago I acquired from a car restorer's supplier (Frosts) a pot of liquid insulation - a rubber solution applied as a liquid and which then dries and hardens somewhat. I gave the dodgy place a good dosing with this, and it will I hope both insulate and give extra strength to prevent flexing of the kink at the critical point. Could get a bit of burning rubber tho' when the motor gets hot.

Incidentally, I am becoming more and more convinced that the Rural is just a Rex with an extra section added in which carries the sound head. All it would need then would be a smaller pulley on the motor to give a lower speed. This makes a lot of sense and may explain a) where there are so few Rexes and b) why there is so much apparent variation in the soundheads (of which more some other time). Maybe some were freelance jobs, with people converting their Rex's with the help of local engineers; maybe there were specialist converters - one of mine has an obviously proprietary (French) ACE sound unit. And of course, all sorts of ad hoccery would have taken place when the Germans demanded conversion to 16mm in 1941.

Once I have done one, it should be easier to do another as, with my drawings, I shall hopefully not have to work things out from first principles again. I've also bought some new equipment which should make it easier, too.

Here is the finished article, painted and ready for final fitting. I made the new inserts for the oiler holes to cover up my mistake in tapping the wrong Rural-Sonorethread. I'm really waiting to give the paint time to really harden off before fitting. Three coats of Satin black Hammerite; I baked it in the oven for an hour at v. low temp, made a pong. Dunno if this will work in drying the paint. Just before Xmas I managed to find a company who would make new geared shafts for me, which I hope to get by the end of this month. Turning my attention now to the design of new turrets to replace the distorted Mazac ones, and to the cam problem for the claw.

The Mazak problem had spread to one of the fixing lugs on one turret, and to a screw thread on the other. I had laboriously to make a fiddly little add-on bit and secure it with tiny screws to deal with the lug. The thread meant carefully drilling out a hole and fitting a small brass bush, held in place by a grub screw, with the appropriate thread cut on the protruding end. This thread was M14 x 1.5, whereas the "normal" M14 thread is 2.0. So I had to buy a special die, which I may never use again. All good, solid, bread-and-butter stuff, but not the stuff of which dreams and website material are made.

This machine is also the one where the gears were stripped and I had to get new ones made - a mad expense but.........It is now back more or less in one piece. A minor irritation is that most of the nuts and bolts appear to be non-standard. The M3 size normally has a pitch of 0.5; the ones on the Rural are 0.6, which of course you cannot buy. Fortunately, I have been able to find most of what I need in my stock of miscellaneous nuts and bolts. I have had to buy the appropriate tap and die, tho'

You may recall that I made a new end cap for the motor to replace one that had suffered Mazac problems and caused the motor to seize. Either some over-sizing of my replacement, or other Mazac distortion in the motor fan etc has caused a problem.

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Have a look at these pix and I will try to explain. Each end of the motor shaft has an internal screw thread. There is also a notch cut across this thread, for a depth of about 2mm. A special washer with lugs engages with the notches, and is held in place by a screw into the thread in the motor shaft. OK so far? On the front end of the motor is a flat pulley for the main drive; at the back is the fan you see here. This is a good, secure method of fixing but, unless (which is perfectly possible) I am missing something, the relative positions of the fan and the pulley are fixed. If, for instance, I wanted to move the fan outwards to give clearance where it fouls the casing, for reasons I have suggested above, I can only do it by moving the position of the motor rotor (nice term that) relative to the casing by going right inside the motor and inserting washers at one end or the other to achieve the desired change of position. I think. If I just try to pad the fan outwards with washers, the teeth on the washer fail to engage with the notch with, as they say, disastrous results. Even a small adjustment seems to make the screw fail to tighten up properly and the fan soon spins loose.

However, I don't like going inside the motor unless I absolutely have to. The wiring is old and fragile and could easily be damaged, ruining the motor completely. Clearances are extremely tight anyway, and the motor rotor could easily hit the windings if moved much, again causing ruin. So I have attempted an alternative approach, by extending the motor shaft with the little brass thingy you see in pix 1&2 (only difference between these is showing both sides of the washer). The problem is, the extension has to be a certain minimum length - there has to be some material left between the threaded hole at one end and the screw thread at the other to keep it all in one piece! Then of course, the fan hits the cover, which in turn needs to be moved out. What is in effect a very big, thick washer seen in pic 3 is in three parts 'cos I only had a small piece of thick enough stuff. Even in alu, this was hard work as it's mostly manual labour rather than machine-aided .I still have a problem tho', in that the little brass bit tends to work loose. I am contemplating either a pin thru the screw thread to engage with the notch (tricky; drilling a tiny hole thru a screw thread without so weakening something that's only 3mm diameter anyway that it breaks.....) or some proprietary compound to lock the thread. In the end, I decided on belt and braces, and made a collar to fit on the shaft, with small screws thru into the notches in the end of the shaft to grip onto the thread of the brass extension piece. This meant boring out the fan to fit round the collar. I bought some thread fixing stuff, too, and will probably use both. At the moment, it's all still in bits as I explore getting the cam altered back to 17.5.

Rural-SonoreRural-SonoreWhile we are here, you might as well see what the switch panel for the Rural looks like. I took the inside pic anyway to give me a guide when re-assembling if need be. The two pins rising towards you out of the picture carry a grid with a (variable) resistance winding for the lamp (200 or 300w); you can see the wiper for the resistance. The switch is totally simple; turn it in either direction and you get on-off-on-off an infinitum.

I thought I would prove my point about a Sound Rural just being a silent Rural or Rex with a soundhead added.

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I thought that, while I was assembling a 16mm Rural, I might as well assemble it as a Rex along the way. Please excuse some rough edges to these pix; I had a very untidy background for these shots and I've been playing with removing it to various levels. Note on the back there are two small round knobs; one controls the lamp output, the other is not connected at all. Obviously, the original Rex had an ordinary series wound motor, controlled by this knob. Just add the sound unit, an induction motor with condenser and voil A Rural! This could explain why the Rex/silent Rural itself is so rare - they all got converted. One wonders if, like the Vox, the conversion was in mind right from the start. You can compare the above with the Rex pictures in Big Brother 1. I must say, I do think it's a very clever adaptation, pre-planned or not.

The lamphouse on these machines worries me. The lamp would be 200 or 300 watts, which is what is marked on the ammeter dial. It burned upside down, like the Vox, but must have been very slim, because there is very little room between the mirror and the condenser lens. In fact, now I've actually looked, it IS a Vox lamp - same pin arrangement and the filament seems to be in the right place. I tested the voltage, but without load the lowest I got with the lamp control turned right down was 17.5v. Unwilling to risk a rare Vox lamp, I used a QI 15v 150w and, under load, the voltage fell to a much more reasonable 13.7 or thereabouts. So if I turn up the lamp control a bit, I should get exactly 15v at the 200w point on the ammeter. Don't want to try the Vox lamp until I have the motor and fan connected, too. Interesting that the Rural with Vox-type lamp was meant to be able to handle audiences of 3 or 4 hundred (it has a 100mm lens). Was there a different lamp with a different filament layout? Obviously, the same layout would not be as effective for both 17.5 and 9.5 (especially the even smaller 9.5 sound image). Maybe their eyes were just better in those days. And as I recall, when Vox lamps were re-manufactured at some point, there was a simplified filament pattern. I find these odd little byways curiously fascinating.


Been working on the soundhead too. This is on the crowded top of my workbench and I have cropped off extraneous material. You can see all the salient features. The sound telescope is just lying there; it fits to the unpainted area. The original sound system was of course a photocell, plus a mirror, highly reminiscent of the Pax. The mirror is the little silver thing, bottom right. It fitted into the little black dome-shaped thing just left of it, which in turn fitted to the main body with the dome protruding into the hollow end of the sound drum. I have made instead a little bracket (seen above the mirror) and fixed a solar cell thing to it using my liquid rubber insulating stuff. The wires from this will be soldered to the wire sticking out of the main body (the wire will have to go out thru the hole opposite the end of the sound drum), then the dome has to be mounted in place and the end cap (square thing, lower left inside the armoured wire loop) put on. To minimise alteration, I have simply soldered the wire to the pins of the photocell mount and, at the other end of the armoured cable, added a phono socket to an existing hole and connected the existing wires to that. It means the machine could be very simply re-fitted with a photocell if desired.

I have finally finished re-commissioning my 16mm Rural and it works just fine. If one was to use it, there are various improvements it needs, eg shorter throw lens (one fitted is 100mm) and more light (tho' the Vox lamp works fine), but I plan to do these to the 17.5 version if I can get it converted. I do have lenses that will fit the barrel, but they come nowhere near being able to focus. It's a crude but solidly-built machine, obviously intended for heavy use in the French countryside. Here are pix. Sorry about the pink background, but it's the colour of my cinema. It's called bull's blood, tho' I think bordello red might be a better description. It was as near as I could get to real cinema colour, and it had to be very dark to avoid reflections lighting the whole place up.

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You will note it has rather limited spool capacity - that bottom spool is 1000'. I suppose that's what you would expect from a 17.5 machine. One can only assume they ran them in pairs, maybe even with some lash-up changeover unit, almost certainly using just the one amp. Threading thru the sound head is tricky, tho' it was probably easier on 17.5.


 BB1 BB2C Home Talkie Super Rural