Film-Tech Forum ARCHIVE: Losing Loops In Simplex

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Posted by Michael Elam (Member # 788) on 10-01-2006, 01:01 PM:

I have a Simplex PR 1050, at random it looses it loop at the holdback sprocket, (the one underneath the intermittment)it doesn't damage the film or the sprocket and it may run for 5 minutes or an hour before it will do. I have inspected the sprocket teeth, tension bands,tension, changed the intermittment, for testing I only thread the projector head and not the soundhead. Any ideas would be appreciated.

Posted by Dominic Espinosa (Member # 2122) on 10-01-2006, 01:12 PM:

Is it gradually loosing it over time or just jumping it completely?

Posted by Rick Raskin (Member # 1561) on 10-01-2006, 01:42 PM:

I would check the pad roller spring tension. Also, check that the roller clearance from the sprocket is only 2 film thicknesses and not more.

Posted by Michael Elam (Member # 788) on 10-01-2006, 03:01 PM:

Been there, done that. It is not consistent,a loop of flim or the print may run 5 minutes or 30 minutes before it does it.
I've changed and check the pad rollers,the clearance of the pad rollers,the tension shoe, the tension bands,replace the intermittment, and replace the entire holdback sprocket assembly.

Thanks

Posted by Kevin Raisler (Member # 1761) on 10-01-2006, 04:44 PM:

Michael, could it be a gear or belt problem? I had a sound head that lost loops and it turned out to be a belt slipping on its sprocket.

Posted by Randy Stankey (Member # 64) on 10-01-2006, 04:49 PM:

The 1050 is that monstrosity of a projector with the flip-up gate. Right?

Isn't the intermittent sprocket pad attached to the gate?

I'd be sure to check that the gate isn't bent or damaged and that the pads are properly attached and aligned.

I really liked working on Simplex projectors but that 1050 model was certainly not their best effort. [Frown]

Posted by Michael Elam (Member # 788) on 10-01-2006, 05:11 PM:

You're thinking of the 1060 with the flip up gate, the 1050 is virtually the same as the Simplex 35,with a few changes and a turret added to it. It uses two belts, I have replaced both.
The confusing part to me is why it acts up randomly, not knowing for sure when it will happen.

Posted by Mark Gulbrandsen (Member # 72) on 10-01-2006, 07:03 PM:

Aside from checking for proper clearances check the gear on the sprocket's shaft. Its a tiny gear and I've replaced lots of them. A film pileup can strip that gear easily. Its also the most failed gear on the Simplex 35/70 since that tiny gear is holding back the 70mm film.

Mark

Posted by Monte L Fullmer (Member # 2797) on 10-01-2006, 07:07 PM:

yea..had a 1050 was doing the same thing. Found out that the assembly casting was loose against the main casting,thus had a slight tilt downward causing the "tooth hop" against the vertical shaft drive sprocket.

Wore the formica sprocket out pretty well with it doing this...

Posted by Michael Elam (Member # 788) on 10-02-2006, 06:34 AM:

Thanks again, the ENTIRE holdback sprocket assembly has been replaced with a NEW one,like wise for the intermittment,the tension shoe assembly,and both belts.

Posted by Michael Elam (Member # 788) on 10-04-2006, 06:43 AM:

The answer is....The upper and holdback sprocket has a dowel type pin that fits into a groove on the sprocket shaft, this pin was coming out on the upper sprocket, it would work itself out far enough to hit the stripper pulling out the loops, a hammer and punch fixed it up.

Posted by Rick Raskin (Member # 1561) on 10-04-2006, 06:50 AM:

Good job. Thanks for the update.

Posted by Mark Gulbrandsen (Member # 72) on 10-04-2006, 08:13 AM:

I've had that happen many times in the past. All you need to do is put a drop of loc-tite on the pin and put it back in place. I'm not a big fan of hammers and punches around sprockets.

Mark

Posted by Charles Greenlee (Member # 3856) on 10-04-2006, 12:12 PM:

Yeah, I keep loc-tite in our booth. The blue stick kind, meduim hold. Our tech kind of gave me a look when he saw it, and then I showed him what I use it for, and he nodded and said that it was a good idea. Its really good for keeping the rollers on your elevator, and other places, if they keep working loose. Usually, I can just tighten them and they're fine, but a few work loose once every sevral days. The med. hold is enough to keep them on, but not make them permanently stuck.

Posted by Steve Guttag (Member # 268) on 10-04-2006, 04:51 PM:

The Loctite sticks are up there with sliced bread! Finally an adhesive that one can carry around in a tool case that doesn't go bad or ooze out! I use the Blue all the time and the red when it is the right thing for the job. I also like the sticks because they don't "run" when allowing them to cure.

Steve

Posted by Frank Angel (Member # 248) on 10-06-2006, 05:57 AM:

quote: Michael Elam
the ENTIRE holdback sprocket assembly has been replaced with a NEW one,like wise for the intermittment,the tension shoe assembly,and both belts.

Eeegads, Michael....you did all that and all you needed was a stick of loc-tite? [Eek!]

Poor baby.