Film-Tech Forum ARCHIVE: What are likely sources for vertical scratches from a Simplex XL?

This is topic What are likely sources for vertical scratches from a Simplex XL? 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=009610

Posted by Justin Hamaker (Member # 2165) on 11-12-2008, 05:59 AM:

Last night I ran a 6-7 minute loop of film about 8-9 times on the Simplex XL at our drive-in. On about the 5th or 6th pass I started to notice emulsion side vertical scratches developing on the right side of the picture - less than 1/8 of the way in from the edge of the image. The scratch started out as just one speck in the top half of the frame and progressively became more defined with each subsequent run. The scratch was perfectly vertical and was present through the entire loop.

I looked through the entire film path and could not find any place where the picture portion of the film was touching a roller or guide post. The only possible culprit I could identify was the rubber piece of the sound drum pinch roller. Is there something else I should be looking for or is this likely the culprit?

For what it's worth, the platter is a Christie AW3 with the older black rollers and metal brackets. The timing on the platter decks is good and the film was not dragging on any of the brain posts.

Posted by Kenneth Wuepper (Member # 1174) on 11-12-2008, 08:22 AM:

Justin,

What a great way you have devised for checking out your film path. This goes to your desire for a perfect show. I might make a few suggestions for "where to look" for your abrasion of the emulsion side of the film.

If the scratch begins in one point on each frame, it must be related to the intermittent controlled part of the film path. One of the most obvious areas to look is the clearance between the aperture plate and the film. The adjustment of travel for the closing of the film trap can become loose and let the film get pressed against the edge of the aperture plate. This adjustment also effects the setting of the band tension so you may have the tension control set at 1 or less.

The upper loop sensor wire that trips the fire shutter can also touch the film intermittently with each subsequent frame. If there is no longer a fire shutter in that machine, the wire sensor serves no purpose. Only if there is excessive upper loop size can the film even touch this sensor.

Similarly, there are ridges in the casting in the area of the lower loop. These ridges prevent an over sized loop from contacting the metal casting in the area of the image. The film loop is changing in size with each advancing frame.

The threading of the sound area can be modified to skip the drum, scanner and tension roller thus eliminating those parts from your consideration. If there is still scratching, the reader area of the sound head is eliminated as the cause.

Other areas to consider, if the scratch is not intermittent in nature are: The flame trap at the top of the projector casting. Sometimes dirt can catch there and abrade the film as it passes through the rollers. The fail safe can also be a cause if it is not cleaned properly and dirt accumulates on fixed surfaces of the sensors.

I hope that this was helpful. Keep up the good work and may you have many perfect performances in the future.

KEN

Posted by Justin Hamaker (Member # 2165) on 11-12-2008, 02:33 PM:

I wish I could take credit for running the loop for the sake of trouble shooting. It was actually a short loop of images being used by a production crew that was shooting a documentary.

Posted by Jack Theakston (Member # 4484) on 11-12-2008, 03:11 PM:

I think it's unlikely to be the sound-head if the rubber drum is moving. A lot of people criticize that design, but I've never had trouble with it and as long as you keep it clean, there is no margin for error there.

Is this in the picture area? And have you tried running something green through to see if you see it on the first pass? If you do, then obviously it's before the gate, but if not, you'll probably find the error on a roller.

Another check to make is the tension bands in the gate. Sometimes garbage builds up there that you don't see if you don't take out and clean the gate, but can cause nasty scratches.

Posted by Carl Martin (Member # 1146) on 11-12-2008, 03:16 PM:

if the scratch is quite close to the right extreme of the image, the inner flange (on the inner side of the sprocket teeth) of a pad roller is often responsible for that.

since these scratches are most apparent over bright imagery, it may look like they are only on, say, the top portion of the frame if the image is lighter there, as is often the case in exterior shots. also, keystoning can cause the lower portion (with a downward tilt) of the scratch to disappear into the masking.

i could swear i've seen such a scratch with a 4x per frame beat to it, as if the slight difference in flexibility of the film due to the perfs caused the intensity of the scratch to vary.

Posted by Joe Redifer (Member # 3) on 11-12-2008, 03:21 PM:

Justin, are the scratches actually a bunch of green specks on the right hand side of the screen all in a vertical line?

Posted by Justin Hamaker (Member # 2165) on 11-12-2008, 03:38 PM:

Joe, it started as just one speck, but with successive runs it became more of a line. I know this suggests something that is hitting the film intermittently. It started at the top 1/3 of the frame, but gradually covered most of the frame top to bottom.

Posted by Joe Redifer (Member # 3) on 11-12-2008, 04:19 PM:

I have seen random green specks on my Simplexes on the right hand side (you didn't say which side yours were on), but only on one print. This suggests that it must have been some kind of misthread or a few misthreads. The only thing I can really think of is the lower loop being a bit too big and hitting the back of the machine slightly.

Posted by Steve Guttag (Member # 268) on 11-13-2008, 08:54 AM:

Justin,

Make another loop using fresh scratch free film (unused preview, for instance)....run it a bit to ensure it is good and scratched. Then take a red or other easy to see marker and fill in the scratches with it...you need not be too neat and you don't have to layer it in...just make sure you hit the scraches with the marker.

Then thread up and run it again for a bit. Then look for the red powder in the projector/soundhead. It will normally point you to the culprit.

Steve

Posted by Jim Cassedy (Member # 4115) on 11-16-2008, 09:57 AM:

I like to run unexposed loops of camera or print film.
The emulsion is a bit softer than what's on a release
print and it's easy to spot any scratches on the
'virgin' film surfaces.
Also, similar to Steve's "red marker" trick above, if
the emulsion is being scratched the beige-ish flecks
are easy to spot in the projector to help track down
the cause.

Posted by Don Olson (Member # 90) on 11-27-2008, 04:19 PM:

There is a sharp piece of something ( exploded bulb maybe? ) stuck in your pressure roller. On each revolution it pokes one more hole in a frame. They line up perfectly and look more like a scratch at each pass.

That's my guess.

Drag a razor blade across the roller and find where it "sticks".

Goodluck.

Don Olson