Film-Tech Forum ARCHIVE: Century 35 mm proj. causing scratches

This is topic Century 35 mm proj. causing scratches in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Chris Mulligan (Member # 6921) on 06-08-2012, 04:55 PM:

Hi folks. Some minor but noticeable scratches have appeared on the 35mm prints that came through recently. I have a relatively limited vocabulary of projector maintenance, and I'm interested in suggestions for troubleshooting this. We're using a Century "C" , with a platter system. My inuition is that I should check the fine adjustment of the positioning on the rollers in the projector, to be sure that the film isn't being pulled into contact with anything. Also the aperture/ pressure plate, would be a possible cause of a scratch, if they are ? slightly off , although I have not changed our setup in that sense. Is there a go-to for addressing this issue? -Thanks , Chris at the Cable Car

Posted by Justin Hamaker (Member # 2165) on 06-08-2012, 05:41 PM:

Chris, what do the scratches look like? Are they horizontal across the frame? Do they run vertically down the frame? Are they intermittent or do they have a steady pattern? Are they always in the same area of the frame? Are the scratches black or are they green/yellow?

Posted by Chris Mulligan (Member # 6921) on 06-08-2012, 05:59 PM:

The scratches are intermittent but frequent / seem to fade and reappear, but quickly, for the duration of the print, possibly more noticeable toward the end. They are mostly center to right, less on the extreme right. They run vertically down the image, and yes, are consistently in that area. Hope that helps. Thanks, CM

Posted by Justin Hamaker (Member # 2165) on 06-08-2012, 06:05 PM:

If the scratches are perfectly steady - meaning they don't drift from right to left, then you'll want to look for something in your gate/trap, around one of the sprockets, or possibly the sound drum.

If the scratches tend to drift from side to side, they you want to look for something along the film path. Possibly a post on your platter with a burr, or a roller with burrs.

If the scratches are black, you can sometime get rid of them by running a Kelmar media film cleaner with the media rolls saturated in Film-Guard.

It's also possible your platter is running a little slow and causing the film to drag on a post. In this case you want to get the platter timing adjusted.

Posted by Monte L Fullmer (Member # 2797) on 06-08-2012, 06:23 PM:

His description the scratches sounds like he has an STRONG platter that the return roller that returns the film back to the decks are slightly bent upward causing the film to ride on the inside edge of the rollers esp when the platter gets full.

Posted by Chris Mulligan (Member # 6921) on 06-08-2012, 06:28 PM:

Wondering if you could tell me a little about the platter dragging diagnosis ; that seems possible- the films have peen plattering uneven ( IE. how they sit on the platter) which seems to me like an issue of what rate the platter is turning at. So I suppose it could be related (?) - In that scenario, how is the damage being caused? CM

Posted by Chris Mulligan (Member # 6921) on 06-08-2012, 08:17 PM:

And: the scratches seem black, rather than green.
Seems like the platter speed is the issue. CM

Posted by Monte L Fullmer (Member # 2797) on 06-08-2012, 08:21 PM:

ALL return rollers shafts should be level with the deck. If the've been bent up (it bends the metal tab that the shaft is attached to) due to brainwraps, the film will head to the higher flange of the roller and actually be rolling over that edge scratching the film pretty bad. I simply just rebend the metal back to flat to cure this issue.

Also, the assemblies can be adjusted by loosening up the 7/16" bolt that mounts the assembly to the tower.

Film edge, that leaves the roller, should be just touching the edge of the platter heading to the ring.

EDIT: if black, then you're winding soundtrack up and the base side of the film is tagging across the rollers.