8mm Forum: ST-1200 chewing while threading

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Posted by Vidar Olavesen (Member # 3354) on December 12, 2014, 01:38 PM:

Anyone know what to do to get the machine to thread without chewing like this?

This was clean and newly cut before threading and comes out like this

Posted by Andrew Woodcock (Member # 3260) on December 12, 2014, 01:45 PM:

Vidar there is no one single fault that causes this. There can be dozens of reasons as to why this would happen. It is all a case of process of elimination and logical thinking to narrow it down somewhat. Once you have been able to do this, then someone on here will no doubt have experienced the same on their machine.

I have to say, if I could find a decent SH30 for my optical prints, I would never want to see another Elmo in my living room in my lifetime based on past and present experiences.

Posted by Vidar Olavesen (Member # 3354) on December 12, 2014, 02:06 PM:

Well, I know it happens at the point where you thread the film ... It's before the gate and onto the first sprocket wheel. I was thinking, crooked path, but can't see anywhere to adjust anything

Posted by Steve Klare (Member # 12) on December 12, 2014, 02:08 PM:

Is this one film that this happens or all of them?

(process of elimination!)

If you look at the first couple of frames of an experienced print, you can usually see a shallow gouge where the sprocket teeth are hunting for a perf to drop into, but this looks like they tore into it.

Are all the teeth on that first sprocket in good shape?

Posted by Mathew James (Member # 4581) on December 12, 2014, 02:10 PM:

Interesting how it is basically starting at the left tip and chewing mostly on the left sprocket hole side.
If you happen to see it happening when you feed it in, is it happening on the first sprocket just past the auto-thread opening, or is this happening after the sound head when it goes to the underside sprocket?
My hunch i it i happening right at the start before you even get to the gate. I wonder if loosening the screw on that sprocket, re-centering the sprocket gear and retightening the screw would help. It can't hinder if it is already chewing, but i would obviously use an old reel you don't care about....
My St1200HDM, so far, is doing pretty good.... I haven't chewed any film yet but did have one time when the film, after passing the sound head, didn't go into the guide but found a way through but i caught it quick and reversed before any damage.
No matter how many positive experiences i have, i still seem to always keep the side open and watch, just in case because it just takes that one time to put me on edge.... [Smile]

Hope someone chimes in to help you!
Matt
EDIT: Vidar beat me to the post...but my comments may still apply.Cheers.

Posted by Andrew Woodcock (Member # 3260) on December 12, 2014, 02:23 PM:

Are you using the half moon trimmer that you get with an Elmo Vidar?

2/ Is the theading shoe locking down as it should forming a very close coupled loop?

3/ Is there any wear or obstruction on your top guide shoe or other plastic threading parts?

4/ Are the two top rollers fitted around the top sprocket free of obstruction, free turning, correctly fitted and lubricated?

5/ is the top sprocket revolving freely and at the correct speed relative to the bottom sprocket but in the opposite direction?

Ask yourself all these questions Vidar by inspecting the relevant parts and dismantling where necessary and then you may be nearer to finding a solution hopefully.

either way by the looks of things your film is being ripped by the top sprocket one way or another so as it is at the very start of proceedings, it shouldn't be too difficult to spot hopefully.

Posted by Vidar Olavesen (Member # 3354) on December 12, 2014, 03:04 PM:

It's mostly all films (which all threads fine on my two other 1200's)

Using the Elmo trimmer and it looks fine. I will inspect the sprocket wheel for any damage.

Thanks, have something to check now. I am a bit scared something falls off and I don't know where it should sit. Would anything inside (on the back) fall off if I remove the whole sprocket wheel?

Posted by Steve Klare (Member # 12) on December 12, 2014, 03:17 PM:

I think the place to start is rotate the sprocket manually so you can give the teeth a good look. Maybe one is bent or broken.

If you can move the shutter wheel manually from the machine's right side, you might not even need to take the back off.

You can pull the sprocket off later if you need to. It's not that bad.

Posted by Andrew Woodcock (Member # 3260) on December 12, 2014, 03:21 PM:

No my friend, feel free to take all the top sprocket parts off. No harm will be done and quite frankly this is one job that any ST1200 user needs to do quite regularly to lubricate the rollers and thoroughly clean the plastic parts. Just ensure you use decent instrumentation screwdrivers so as not to round any of the screw heads. That is the only real watch out along with ensuring the two tiny rollers are put back the right way around.

Posted by Vidar Olavesen (Member # 3354) on December 12, 2014, 04:17 PM:

I've replaced the sprocket wheel (the thin part only) with one from a projector without this problem. Didn't help. It seems the angle of the feeder is wrong ... Like the film hits straight onto the sprocket and not going under. I hear ugly noises when the film reaches the sprocket wheel. One out of ten times, it goes in without any noise. But I can't seem to find any way to adjust the angle of the feeder. It's on a metal piece with a long pin that it sits on and the metal piece is connected to the small metal clip (tension thingy) and I removed that and put it back on and it worked ... Once :-(

Posted by Andrew Woodcock (Member # 3260) on December 12, 2014, 05:12 PM:

You are very good at the digital tech side of things it would seem Vidar. Try posting us a video so we can exactly see what's going on in there. remember a picture often tells more than a thousand words..

Posted by Vidar Olavesen (Member # 3354) on December 12, 2014, 05:21 PM:

Will try that tomorrow. Thanks for all suggestions

Posted by Tom Photiou (Member # 130) on December 13, 2014, 05:24 AM:

Vidar, if it was me I would remove the top sprocket together with the whole top green guide and clean it all up and take a good look, make sure the screw that holds that toothed ring to the sprocket is tight and hasn't worked loose, all the little rollers are free to spin, get it back together and try again.
If you want me to scan and e mail you the exploded diagram let me know. Unless someone already has a file they can load onto here for you. [Wink]

Posted by Barry Fritz (Member # 1865) on December 15, 2014, 11:44 PM:

Is the auto thread lever staying locked down when you are feeding the film?

Posted by Andrew Woodcock (Member # 3260) on December 16, 2014, 12:06 AM:

Barry, quetion 2 that I put to Vidar was whether or not the threading shoe was locking down.

As Vidars machine cannot get beyond the first sprocket without chewing the sprocket holes on the film, it cannot be that the shoe or "auto lever" as you are naming it, can be sticking in the downward position because this would only cause a problem once the film has made it to the take up reel and has not released the shoe as the electro mechanical mechanism should.

At the point where the machine is chewing film, ie the top sprocket, you want the shoe to be in the lowered position so it will thread correctly.

Unfortunately, in Vidar's case, this isn't happening as it should, but from what he describes, the shoe is at least going downward into it's correct locked threading position.

[ December 16, 2014, 02:44 AM: Message edited by: Andrew Woodcock ]

Posted by Vidar Olavesen (Member # 3354) on December 16, 2014, 04:19 AM:

That is correct. Everything works fine when it gets past the place the film gets "hooked" onto the sprocket gear. It seems to be pointing directly 90 degrees onto the gear, while I would assume it should have a little angle. Can not find anything to adjust on it. Will try the suggestion of removing it all, clean and re-assmeble but need some time for it. So worried something else will fail, as I am totally useless at these things

Posted by Andrew Woodcock (Member # 3260) on December 16, 2014, 04:28 AM:

Surely one of your many film collecting friends or maybe your Son could step in here Vidar if you don't like to take on the task yourself?

I am sure it would reveal something if you were to dismantle the top sprocket and guides, there is very little to be wrong apart from wear or blockage to guides or maybe damaged to the teeth on the sprocket perhaps.

The initial guide does have a location peg as well as a screw to hold to the body of the machine, maybe the location peg is not sat in it's location hole if the guide appears to be at an incorrect angle? It should sit dead square to the frame.

Posted by Paul Browning (Member # 2715) on December 16, 2014, 04:58 AM:

Vidar, the top guide wears flats on it very close to the top sprocket, maybe this has developed a lip on it and is not allowing the film to flex enough to lace correctly, it is quite easy to remove a get a look at, this has been modified on my machine, and now has a roller fitted to stop scratching the film and aid transit through this auto loading mechanism.

Posted by Barry Fritz (Member # 1865) on December 17, 2014, 11:40 PM:

Thanks Andrew. I missed your earlier question. I do understand the function of the lever. I asked because I have seen on some machines that the shoe (lever) does not stay down as it should. Due to wear or age or whatever reason, it does not lock down or may lock down initially but then pops up sooner than it should.

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