Film-Tech Forum ARCHIVE: Verticle Scratches

This is topic Verticle Scratches in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Robert E. Allen (Member # 1351) on 03-14-2014, 03:08 PM:

When I took over this theatre I noticed the films shown in one auditorium were being scratched. I went through the projector, sound head and platter system to make sure nothing was touching the film where it shouldn't. I still have a green scratch down the left side and two light black scratches, one near the left and one near the right. I am running Simplex 35s with Christie AW3s. I've done this for 25 years and am puzzled by this.

Posted by Mark Gulbrandsen (Member # 72) on 03-14-2014, 04:58 PM:

Emulsion is being scraped off some place. You need to run some loops and then look for a small deposit of emulsion. Then you've found the problem.

Likely spots:

Curved runner at the very top. You'll notice the very center of the inside of the runner will be polished from film rubbing because the film is cupping at that point.

Sound stabilizer area

Platter rollers that are cocked or crooked and or may not be spinning freely.

Pay out head. Does yours still have the stupid tension spring inside the middle roller? When those get dry it's enough friction to completely stall that center roller.

Cue Sensor: Switch lever bent and barely touching film?

Just some thoughts.

Mark

Posted by Brad Miller (Member # 2) on 03-14-2014, 05:05 PM:

quote: Mark Gulbrandsen
Pay out head. Does yours still have the stupid tension spring inside the middle roller? When those get dry it's enough friction to completely stall that center roller.

While I agree with Mark the spring should be removed as general practice, even if a platter roller COMPLETELY seizes up, it will NOT scratch the film. (SRD/SDDS tracks, yes, but not the analog sound or picture area.)

A screenshot of the scratches would be most helpful, as well as a few shots of your system threaded (projector and semi-wide shots of the platter and film path).

Posted by Justin Hamaker (Member # 2165) on 03-14-2014, 06:47 PM:

I had a similar issue with a Simplex 1050. What I found was the tabs that limit the mounting block for the intermittent shoe had broke and was pressing on the film.

Posted by Mark Gulbrandsen (Member # 72) on 03-16-2014, 12:10 PM:

Brad...

I have actually had them scratch when they stall! The film has to be pulled so hard that it actually can cause estar film to cup and rub as it is pulled through. I use to rip those springs out... then my idiot boss would go around and put new ones in. I would rip them out again on my next visit. No one ever gave them sufficient maintenance in between visits to keep them lubricated well enough between service visits. It should have been a Teflon slip mechanism of some sort. I also thought about a magnetic clutch as well but you couldn't do that on a 70mm latter. Some pro film cameras film magazines use magnetic slip clutches for feed and take up and it works very good and never requires calibration.

Getting to the Simplex curved gate on the 1050... I also found a film cupping issue on these at the upper loop. We had an AMC here that we were servicing and they kept getting light scratches down the center of the frame. This one took a bit of detective work because you could not see it happen with the naked eye. There was one clue of a polished spot at the top center of the runner. Add a variable strobe to the equation to slow down the film motion and there it was. Every time the film pulled down it would cup and rub on the top inside center of the curved runner. Lightening up the lateral guide roller springs helped but did not alleviate it completely. I found that threading the top loop to an exact size kept the film from cupping. But the AMC folks knew better and continued to thread with a large upper loop as they had been trained to do at the AMC training school. This way they had a full framing rotation available (As per AMC training class) since none of them could learn to thread in frame.

I have found this issue on just about every 1050 in existence! Crappy swing out gate!

Mark

Posted by Buck Wilson (Member # 5885) on 03-16-2014, 01:01 PM:

I hate those gates with a burning passion. I also found that if the top loop is anything larger than a perfect waterfall into the gate, you're asking for problems on top of it just running that much louder.

Posted by Frank Bolkovac (Member # 6201) on 03-16-2014, 10:09 PM:

How about worn out intermittant sprocket shoe. The outside shoe is worn down far enough that the inside shoe is touching the picture area.

Posted by Mark Gulbrandsen (Member # 72) on 03-17-2014, 04:07 PM:

Totally agree Buck! It was a good thing they discontinued those as quickly as they did. Problem was that most of them seemed to end up in my service area! I kept one that's sitting in my garage right now. Gonna make a table lamp out of it this summer...

Mark