Film-Tech Forum ARCHIVE: Platter Scratches

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

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=005264

Posted by Edward Jurich (Member # 1787) on 08-29-2003, 09:22 AM:

All of a sudden our platter system is causing scratches on the right side of the picture. I couldn't find anything wrong with the platter rollers but noticed that the scratching would stop when a splice went through (the scratches come and go).
What I did find was the first roller on the top of the 35/70 Norelco has flat spots where the 35 film seats and the film tends to slide off position. The roller spins freely so I have no idea why there are flat spots. I repositioned the platter roller above the projector enough to hold the film in place until we get a replacement roller.
One other thing I wonder about is the sound drum. It's hard to see exactly what's going on in that area. The actual drum is behind a stationary guide. Has anyone ever had a problem with scratches around the sound drum.

Posted by John Pytlak (Member # 331) on 08-29-2003, 09:30 AM:

quote:
What I did find was the first roller on the top of the 35/70 Norelco has flat spots where the 35 film seats and the film tends to slide off position. The roller spins freely so I have no idea why there are flat spots.

The roller may be spinning now, but I suspect it once was stuck and not turning. A quick check of the entire film path to be sure all rollers are turning and properly aligned should be "standard procedure".

Posted by Bobby Henderson (Member # 840) on 08-29-2003, 11:44 AM:

I'm confused about the description here between platter versus roller scratches. Most platter scratches I've seen are kind of curvy and mark diagonally across the picture (I've seen some really bad ones like this that dig down into the green or yellow layer). Aren't scratches caused by the roller themselves more vertical in nature?

Posted by John Pytlak (Member # 331) on 08-29-2003, 11:59 AM:

Classic "platter scratches" are cause as the film surface rubs against the rotating platter surface, usually due to a mispositioned guide roller. If there is a burr or rough spot on the surface of the platter, each time it rotates past the surface of the print, it causes a characteristic horizontal, slightly diagonal scratch across the image. It can be on either side of the film, depending on the winding orientation.

Some may refer to any scratch in a platter installation as "platter scratches". In addition to the projector and soundhead components, the multiple rollers used to guide the film in a platter installation provide opportunities for scratching if you don't check to be sure all rollers are aligned properly and turning.

Posted by Brad Miller (Member # 2) on 08-29-2003, 12:54 PM:

This is NOT platter scratches. Just because you are running a platter does not mean that it is automatically the fault of the platter. In this case it is the fault of your Norelco projector. It is obvious because you say the scratches disappear when a splice passes. The extra thickness of that splice is brushing things clean in the gate or on your entry rollers until the dirt builds up again to resume scratching.

Posted by Paul G. Thompson (Member # 655) on 08-29-2003, 01:59 PM:

Most of the so-called platter scratches I have seen were do to a derailment of the film on a roller somewhere. It is amazing just how sloppy some people are when they thread those machines. The film can be cocked 45 degrees on the roller and even though it sticks out like a sore thumb, they just don't see the error.

However, I have also seen diagonal scratches in the emulsion side of the film. Many of these theatres that had this problem condemned the platter. It was not the platter that was causing it. It was a sprung or a loose intermittant sprocket film stripper or the loop between the intermittant sprocket and holdback sprocket was too big and the film was slapping things it should not have been slapping in the first place.

Most film damage I have seen through the years was attributed to sloppy operators.

Posted by Gordon McLeod (Member # 33) on 08-29-2003, 02:09 PM:

The norelco scanner unlikely is the culprit as the only contact is on the outer edges on both the drum and the lateral guide
The gate has very heavy relief on all parts as do most of the rollers so I doubt even a flat spot on one would cause much of a scratch

Posted by Edward Jurich (Member # 1787) on 08-31-2003, 10:39 AM:

OK, the platter and platter path is fine. The problem was in fact that first roller in the Norelco with the flat spots. What was strange was the fact that this just started happening all of a sudden even though the roller must have had those flat spots for some time. And I think I know why.
They are a single screen theater doing revival running classic movies, almost always older prints. Business has not been good with normal attendence being anywhere from 50 to 1 per show except on bargan night one day a week when it's OK. So last week (when the scratch problem started) they started showing "Pirates of the Caribbean". The week before, the movie was a mint print of "Viva Las Vegas" and that print left without a mark on it.
What I think has happened is now we are dealing with a "newer" Technicolor print that is leaving emulsion on everything and the film tends to slip off the first Norelco 35/70 roller. I've been cleaning everything (emulsion buildup every day) and the film is now entering the first Norelco roller OK. I guess the reason why the scrathces would stop at a splice is that the splice probably would make the film jump back into position. At least the scratch or two is at the extreme right side of the picture and hardly noticeable. Pity since I went through a lot of trouble putting the print together using clear tape (they always used opaque yellow).
By the way, even though "Pirates" has been out for a few weeks, attendance was way up, even the second weekend. People who have seen it before are coming to see it on the 50 foot wide screen. It's beginning to look like there'll be more current movies running here.

Posted by Brad Miller (Member # 2) on 08-31-2003, 01:24 PM:

Check the alignment on the upper magazine roller too. Make sure everyone is threading the same way (the same twist entering into the projector), as that does throw the alignment a bit off if you set it to be properly aligned with the soundtrack toward the lamphouse and then the next guy threads with the soundtrack toward the screen. This is not a real big issue with rollers that have a fair size flange on them, but if I am remembering those rollers correctly, the flange is barely there making alignment more critical.

Posted by Edward Jurich (Member # 1787) on 08-31-2003, 06:40 PM:

On the 35/70 the roller has almost no flange, just a slight indent for the 35mm film to seat so it doesn't take a lot to make the film slide to the side. There's only two of us threading and it's always sound track up and towards the lamp.
I'm going to take some pictures of this place to post. It was just recently restored with lots of neon and looks really cool.