Film-Tech Forum ARCHIVE: norelco fp20 shedding

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Posted by Craig Mueller (Member # 4912) on 08-18-2008, 01:21 AM:

Hi to everyone, I am newly registered but have been quietly using everybody's great advice for the last year and a half to help bring my theater's presentation up to speed.

I have a norelco fp20 that has a problem with shedding on the edges of the film leaving debris on the side of the trap and lateral discs, but not on the runners and film path itself. It seems that the film edges are essentially getting shaved down to a size the projector is happy with and then after about 10 shows or so the amount of debris subsides. I have tried moving out the little cylinders that tension the lateral discs, but that hasn't improved matters. I use the black delrin trap, and have played with the lateral position of the intermittent sprocket, but still no luck. Any advice would be great, and thanks again for this great site!

Posted by Tony Bandiera Jr (Member # 2365) on 08-18-2008, 02:24 PM:

Hi Craig, welcome to Film-Tech. You'll find a lot of helpful people here and some characters for entertainment as well. [Smile]

As for the issue you're having, first thing to try is to turn the ceramic discs around, if you look closely you may find little grooves cut into the discs from the film edges.

That should give you a good amount of time to run, but if it cures the problem as I suspect it will, you should order up replacement discs.

Keep us posted on what you find.

Posted by Craig Mueller (Member # 4912) on 08-18-2008, 02:36 PM:

Hi Tony,
Thanks for the reply. This morning I realized I left out some facts from my post. The discs that are in are pretty much brand new. Two months old maybe, but they were shaving the edges on day one, and as far as I can see the faces look fine. Another observation I have had is that when our numbered leader is going through it makes a crinkling noise as though it is being warped laterally so I am curious if the sprocket above the gate could be misaligned and if that would cause shedding..

Posted by Mitchell Dvoskin (Member # 751) on 08-18-2008, 02:41 PM:

Just a guess, but is there more crud on the top or bottom discs? If top, then they may be out of alignment with the bottom. If bottom, they may be out of alignment with the intermittant sprocket. Could they somehow not be perfectly perpendicular to the film?

Posted by Tony Bandiera Jr (Member # 2365) on 08-18-2008, 03:24 PM:

Ok, that info helps..

I would next look at the trap runners, make sure that they aren't positioned too close together, so that the film is pinched in the "slots" or "grooves" cut down their length.

Check the skate and runners for any nicks or burrs too...

What is your skate tension set at?

Oh, yeah, and check the height of the skate..if it's set too high it can bind up the film too.

Be sure to carefully re-align the intermittant sprocket too.

Don't think the upper sprocket is causing the trouble. (Unless the shedding is actually happening at its sprocket pad.)

Mark G should chime in soon, he's pretty good at thinking these things through...

Posted by Craig Mueller (Member # 4912) on 08-18-2008, 05:03 PM:

Mitchell, that is an interesting thought, I will have to pay more attention to the build up of debris next day I work to see if it is different top or bottom, but as far as I can see the discs are perpendicular to the film and gate. Thanks.
Tony, there isn't much room for adjustment but the runner do not appear to be too close so that the film gets stuck in the grooves, the tension is set to about one mark negative, anymore and the film tends to start jumping. The trap is set so that there is about maybe 3-4 film thickness of space between the sprocket and bottom of the trap. When I put it lower in the past it could get more unstable on screen. As for the sprocket adjustment- I suck at it. It is tough to get much clearance between it and the inboard side of the gate, but right now there is about a film thickness space.
On screen there is a little bit of weave noticeable and also another observation is that especially in between the top two discs the film curls up a little bit on the edges as if it is being pinched too much and it does this with new runners and trap.
Sorry for the length of my posts, but I hope some of the large quantity of info will help to explain the issue.
Thanks everybody!

Posted by Mitchell Dvoskin (Member # 751) on 08-18-2008, 05:13 PM:

I hate to ask a stupid question, but did you have the same problem with the old discs?

Posted by Craig Mueller (Member # 4912) on 08-18-2008, 05:17 PM:

Good question, the old discs did cause the same shedding and that was why I got the new set of them. Didn't know how expensive a little ceramic disc could be, so I stupidly ordered two sets..

Posted by Mitchell Dvoskin (Member # 751) on 08-18-2008, 05:22 PM:

The horizontal weave in the picture can be fixed by adjusting the end play adjustment. See this thread for instructions. The linked thread refers to the FP23, but the film gate is identical to the FP20.

As too your problem at hand, can you see or hear anything out of the ordinary when you turn the motor by hand with the projector threaded?

Posted by Craig Mueller (Member # 4912) on 08-18-2008, 05:56 PM:

When I turn the motor by hand when it is in the leader I get the crinkling of the film, when I turn it in film, it doesn't make any unusual sound save for a clunking that I think is the shutter's play. as it speeds up/slows down.

Posted by Rob J. Buskop (Member # 3338) on 08-24-2008, 09:00 AM:

It seems like one particular item has'nt been highlighted.
The position of the intermittent sprocket on it's shaft.
The procedure is as follows: Loosen the small screw and nut that
hold it in place on the shaft.
Turn the framing knob fully clockwise against the end stop.
Loosen the lock screw of the outer bearing adjustment with an
allen key and gently turn the top end bearing inwards, until the
end position is reached.
Leave it there for a moment and gently slide the intermittent sprocket towards the projector housing. Between the rim of the
housing and the sprocket insert a very thin piece of paper (double cigarette paper) or a 0.05 mm feeler gauge.
Press the sprocket against this thin "spacer" and lock the sprocket on the shaft.
Hereafter turn the top bearing anti clockwise for 1 eighth of
a turn and carefully lock this adjustment from underneith with
your allen key in the lock screw. Done!
This applies to all "older" FP-20 models.
If you would happen to have a newer variety ( about less than
10 years old) the end gap between the sprocket and the housing
will be much bigger (approx. 1 mm). With these it is impossible
to come to the very narrow gap as required in the earlier models.
So: If you have an older example and you figured that the sprocket should be in the middle..., this might be some interesting info.
Use a piece of very thin paper ( or a double cigarette paper) and
push the sproc