17.5 Home Talkie/Pathé Natan

(This is an edited version of a longer and more diffuse exchange)

Q. I recently acquired a 17.5 Pathé Natan (much the same as the UK Home Talkie). I threaded it up and hand cranked it to watch and see what everything does, and where everything goes, etc. I did this for a while so I felt confident and turned it on. Everything ran smoothly, but YIKES! That thing is moving so fast it scared the bejaybbers out of me. Even if it was running perfectly, it looks like one of the scariest projectors ever, with the slightly offset path through the gate, and the frightening GEM/SON wrap around the body of the machine, and then the sharp turn straight up to the take up, and the crazy sound slide thingy that looks like it scrapes the film? Or does it look scarier than it is?

Now I find it is losing the loops almost as soon as I turn it on. I am perplexed, as I feel like I am threading the machine correctly. I can turn it by hand all day and it runs beautifully, but as soon as I start the motor it almost immediately loses the bottom loop, and then somewhat quickly loses the top. I try to see where things are going crazy and the closest thing I can see is the gate area seems to have more movement than I have seen on other projectors. What I mean by this is the back plate of the gate that is attached to the lamp housing, seems to almost be bouncing around. Does this seem normal?

I am first thinking about replacing the screw just beneath the gate area with one that I can screw in with a roller on it, so it won't lose the bottom loop, especially since that is the harder of the 2 to watch easily (the top one I can see as it is disappearing).

A. I entirely agree - film going thru that fast IS scary.

I don't see how a roller stops it losing the loop. All it will do, surely, is to in effect make the loop smaller, with less slack before it catches on something - unless you have in mind an auto loop former? -so that it gets lost even quicker?  

The correct way is to get the film and projector in good order and thread it correctly. Don't forget that these machines managed to work OK for some years in the hands of God knows who - they will work if treated properly. 

With the Natan/Home Talkie, the threading around the sprocket is critical. You put the "top" (in this case lower) loop in place, but then you have to open the same set of rollers again to thread the "bottom" (higher) loop thru. It's easy for the "top" loop to slip out and as there is no loop worth speaking off, huge damage occurs at once. However, I have found that so long as the film is in perfect repair, it will go thru fine if you get the threading right. But don't trust it an inch - watch the machine, not the picture!  

There are details somewhere on Cinerdistan of a device I developed for providing movement of the sound chute during projection - normally you can only adjust it when there is no film in the chute. I did this 'cos I had quite a problem with a wandering sound track on Lorna Doone - kept getting that snoring noise from time to time as something other than the track got scanned, with no way to correct it. Despite looking scary, the chute does not seem to do any damage; note that the instruction book makes clear the chute must be fully closed with the film bowed.

The back gate should be fixed to the projector by 2 small screws, one visible above the gate, the other you need to take the lens off to see - easiest to adjust this one with the screwdriver thru the nozzle at the front of the lens housing. If either of these is loose, it could affect the gate. Make sure they are tight, but with care - not a lot of thread to play with. The screws have to be v. short so as not to protrudethru the gate - may need a washer or 2 under the head. There is a bit of adjustment for framing. Of course, if someone has been careless in the past and stripped either or both the threads, we have a problem of a different order.

Q. I did just notice something that may be part of the problem. The bottom roller on the one sprocket wheel does not seem to keep the film tight against anything. I noticed that even with everything all threaded up I was able to slip and slide the film that is entering the gate as if it were not even one the sprockets, perhaps it is simply slipping off the sprockets. I looked at your pictures, and while yours does not seem to be completely pressed up against the sprocket wheel, I am guessing there is just enough space so that when the film is there it is touching. I checked the hole the pivot arm clicks into and it does not seem to be worn at all, but there definitely seems to be too much play between the sprocket wheel and the rollers. I've included some pix.

I think I have at least figured out why the top loop is being lost. After much watching, hand cranking, and very brief motor running it appears that the bottom loop is in fact the one going away, then because of the slip the top starts vanishing. My best guess is that the film must be just shrunken enough so as to not reach the sprocket causing it to slip before heading up to the take up reel. I am guessing that it has about a total of 2 - 3 sprockets worth of play before the loop is entirely eliminated, and once it misses that first sprocket, it is done for. My question then becomes is there a way to avoid this or compensate somehow? It seems to have something to do with the speed as well, because I can hand crank the same section and it won't slip. Is it possible that when things are moving along fast the rollers are not making as tight a connection? Maddening.

A. OK, leave us look at this logically. If you are losing the bottom loop, this means one of two things:-

1) The film is entering the loop slower than it is leaving, so we have a gate/top sprocket issue;

2) The film is leaving the bottom loop faster than it is coming in, so its a bottom sprocket /take-up problem. 

Stans Treason, dunnit? 

I suspect 2) so let's start there. 

There are three possible projector problems I can think of (at the moment I am leaving out shrunken film cos I have never had a problem):-

a) sprocket retainer roller not close enough to sprocket or slack and can move up and down in relation to the sprocket, or misaligned laterally in relation to the sprocket;

b) belt too tight;

c) clutch tension too great. 

In b) & c), the problem may be compounded by a), or in a severe case may even just pull the film thru despite the rollers being positioned correctly.

I have in front of me, even as we speak, two patterns of take-up clutch (see pic). The spring one is obvious. The second may have a problem with old, solidified lubricant, so just needs taking apart and complete cleaning. I can't recall, but there may be springs under the outer big washer. Belt tension I assume you can deal with.

A bent spool scraping the side of the film intermittently might contribute to the problem. 

Returning to a), the retaining rollers, any problem here can affect the lower loop at either end. The projectors front main casting, by which I mean the one to which the rollers are fixed, is pretty soft metal and I have found that the holes may enlarge, not least the two holes relevant here, ie those for the pivot and the spring-loaded locating pin. I have seen machines with these sleeved up to make up for excess wear. I think on one machine I had to sleeve up AND make a new pivot bolt with a different thread as the old one was no longer fittable. Obviously, if the locating pin hole has enlarged, the rollers will not be held correctly to the sprocket, so when the machine picks up speed........... 

Turning to 1), the gate/sprocket issue, part of this we have already covered above. However, the adjustment of the gate is important. There is usually some small scope for lateral adjustment of the front, fixed gate, as well as vertical for framing. It's important to ensure the sprung gate can move freely when in the closed position. Shut the gate, then push with your finger at the top and bottom, against the gate springs; there should be no grating or sticking against the sides of the fixed portion. As mentioned, the fixed gate may have a bit of adjustment, tho' care is needed to avoid getting the film in a position where the claw does not enter the film cleanly. The lamphouse pivot can also come into play - thin washers either side of the pivot lug at the bottom of the lamphouse may have a role.

Moreover, looking at yore pic (see attached), it seems to me the surfaces pointed out in green should be in contact with those marked red, separated by at most a film-and-a-bit-for-splices-maybe thickness AND unable to move from there. You say the locating pin is firm? Is the pivot firm? Just where is the slack between rollers and sprocket coming from? 

Hopefully the foregoing will give you scope to identify the exact nature of the problem. Then we have to move on to a solution.