The Natan 175
The Natan 175 was the obvious precursor to the Home Talkie, but there are differences. I saw a decrepit example at Argenteuil and noted two differences from the UK model (there may of course be others). First, the mechanism sits lower than on the Home Talkie and on an "island" plinth on top of the lower front part of the amplifier casing, with a gap between this plinth and the rear of the base. On close inspection, the top right picture on page facing P68 in McKee seems to be of this type. The upper picture on P67 (ibid) is the UK type, with the plinth for the mechanism an integral part of the amplifier casing. On the French machine, the connections from motor and lamp to the base are tucked in much more closely under the motor, into its own plinth. Pathescope actually used a picture of the Natan in their advertising for the Home Talkie. It is interesting, if idle, to speculate that the very slow process of getting the Home Talkie out into the market was down to settling the new specification for the revised machine and letting contracts for construction; this might have meant pictures of the Natan 175 had to stand in for a while until the first Home Talkies were available.
The other difference was that the lens housing was mounted with somewhat larger fixings on the French machine. With a little imagination this too can be seen in McKee. What is not seen, however, is that the upper front portion of the lens housing had been notched to form a short "rack" with the fixing knob acting as pinion, as I found when I finally acquired one (albeit only a derelict mech). The effect is to pivot the lens housing around the lower fixing point. My guess is that this was a primitive form of framing or racking, no mechanism for which exists on the UK version. I also had some impression that the French machine was a tad smaller. If so, this might be to accommodate the need for a 240v to 110v transformer for the UK. Oh, and the logo on the plastic end cover for the lamphouse is different.
Here are some pix Ian Green found for me on French ebay, some of which are also used at the start of this Talkie-Natan page. They show the inordinate lengths to which your true cine nerd will go; the first pix are a conversion to 9.5 of a 17.5 Pathé Natan, (tho' I have since learned that similar experiments were done on other machines, including the silent Rural). The last two I'm not too sure what is going on. The last pic may show the way Pathé did the "direct reading" of the sound track that was referred to in adverts for the 1938 blimped Home Talkie - still no sightings of that, tho'.
However, the most important thing for me is that they provide pictorial evidence of the principal differences between the Natan and the UK Home Talkie. Now, whether the Natan was ever sold with just the "island" plinth and not the bigger one, I know not. However, Grahame Newnham told me that the Natan was sold without amplifier, for people to hitch up to their radio's or, I suppose, to the Rural amplifier, which was a separate unit and not integral. What we need is a French, English-speaking 17.5 enthusiast to tell us all about it. The only other difference between the Natan and the Talkie is that the latter has a channel at the base of the combination spool arm, where tha Natan seems to have had a lip on one side only. So, after that brief digression, we can revert to the Talkie in the knowledge that nearly all I have to say will apply equally to the Natan.
Talkie Spool arms
I find that the design phase of a project can take me days of thought and false starts. The question of the missing spool arms for a 17.5 Home Talkie I am refurbishing is a case in point. The drawings you will see below - still only theoretical as work has not started - are the third major design attempt over a period of many weeks. As I have no spool arms and am starting from scratch, I thought I should at the same time make them suitable for 2000' reels - the normal 1000 ft capacity means a reel change every two reels. But the securing/locating pins built into the machine seemed to me a tad lightweight for this job - they are simply studs fixed into only about 0.25 inches of casting. The extra weight and leverage of a full 2000' spool seemed to be asking a lot. So I came up with the idea of using the bolts that hold the two halves of the main mechanism together as extra support. All this, of course, is in pursuit of a solution that makes no permanent alterations to the machine which, as you should know by now, has become one of my main rules.
#
My solution is to add a block to the machine, using the existing pins for location and with one of them extended to use as a fixing just the same as the original. Extra strength comes from a steel plate at the rear. The block is then drilled to take spool arms as per the old style B&H machines, round-ended arms into a hole, but with pins to ensure the arms go in on the correct alignment. You will note the two arms are not in identical alignment; correction for this will be made when I come to the spindles at the other end. I also have to consider how to drive the take-up. Will the existing method suffice, maybe with a double pulley part way up the rear arm to which the existing belt would go, with another belt from there to the end?
Inevitably, some changes have had to be made during the actual manufacturing process. I found that the existing spool arm securing pins were not, as I had hoped, removable, so I couldn't simply insert a longer one as planned. Instead, I made a rod thick enough to take a matching screw thread. (As I ought to have guessed, the thread on the original pins is not a standard one, so required purchase of a special tap and die.) This meant a larger hole through the block, leaving less room for a hole to take the rear spool arm, so I had to reduce that to 9mm. The other significant change to the original design is that I decided to make the rear support plate follow the profile of the bracket block. It may all sound straightforward, but involved many hours of work for me.
My original intention was to take some 12mm square aluminium rod I had to hand, round off one end to an exact fit into the hole in the bracket block and make spool spindles to fit. However, given the amount of work I had already done, I baulked a bit at this. I happened to have a pair of old-style B&H spool arms and, as I intended anyway to use 16mm split spools.. The point about 16mm splits is they can be widened slightly with a washer. I would intend just to have 3 or 4 such spools and to build up films before showing and return them to their normal spools after. Also, the spindle size is actually the same as 17.5 so, with holes for the 17.5 pin to engage into, they can if needed be used on a standard 17.5 spindle, although for my present purpose this isn't an issue. The B&H arms also have a well-proven take-up arrangement that handles 1600 2000 ft reels, something I was a bit dubious about just using a simple belt arrangement as per the Home Talkie.
What I did, therefore, was to make adapters to fit into the B&H arms at one end and the new block at the other, with screw-in knobs as retainers as usual, to avoid any material alteration to the originals. If I had my time over, I would make one or two things a bit different. The adapter for the rear arm would be enlarged to the same diameter as the B&H arm and gently tapered down to the bracket block. This is cosmetic, but more significant is the fact that the internal bores of the B&H arms, never having been intended for use, are I think off-round slightly and also are stepped and tapered. Much closer attention to fitting the adapters more exactly, and more deeply, into theses bores would give a firmer fit. You will see in the last pic I tried two different approaches, a lump on the side to fit into the slot in the B&H arms, and a longer, straight-through securing screw. I think it still needs more work to ensure the whole arrangement cannot twist, eg under the pull of the take-up.
Another thing I found was that with the longer spool arm at the rear, the take-up belt, even when correctly crossed, fouled the flywheel. Fortunately, a simple solution was possible by lengthening the projector thru bolt and adding a couple of Meccano(TM) pulleys. As you can see, I need to shorten the belt a bit - the B&H belt is tight, relying on the arrangement at the end of the arm to provide slack.
The other issue, which I have yet to address in detail, is whether the arms line up with the film path sufficiently well for practical purposes. As you may recall, the hole for the rear arm had to be offset slightly to clear the original mounting pin. I had planned to deal with this simply by where I fixed the new spool spindles I planned to make. We shall see.
The reason I have not yet done a full road test is simply that I want to leave the parts I have newly painted as long as possible to harden before re-fitting everything; this is why in the pix the machine is mounted an a wooden baseboard (it falls over else with those long arms on). There is more yet to do arranging the sound reading, covering various holes in the base and of course painting these new bits wot I have just made, and maybe the B&H arm too. All of this, however, was a bit short-circuited by the acquistion from Ian Green of a completely different and, I have to say, much better design of spool arms for the Talkie.
It is altogether simpler, more rigid and more robust. I guess I just wasn't cut out to be a designer as I do have problems doing spatial visualisation. In fact, this looks much like the work of John Cunningham, who was such a clever engineer I can't feel too much shame.
The mechanism itself also needs work - I don't think it has an oil-tight seal (I think it runs with a small puddle of oil at the bottom, which is picked up by the main gear wheel, which is about 4 diameter, and splashed about the insides generally. I suppose, come to think of it, you'd like some chitterling pix as well while I have it dismantled.