Film-Tech Forum ARCHIVE: Failsafe Close Call

This is topic Failsafe Close Call in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Edward Jurich (Member # 1787) on 09-13-2003, 09:39 AM:

The failsafe had stopped working, would not shut the projector off. We ran that way for a couple weeks. I tore into it a couple days ago and fixed it. Last night during a 10PM showing of Monty Python Holy Grail, about 2/3 into the film the projector stopped. I ran in and found the film had wrapped around the payout causing the failsafe to shut the projector off. Talk about being lucky, hate to think what would have happened if the failsafe had not been working.

Posted by Don E. Nelson (Member # 1049) on 09-15-2003, 03:03 PM:

How does a fail safe work, I have never seen one.

Posted by John Pytlak (Member # 331) on 09-15-2003, 03:10 PM:

A tension-sensing failsafe runs the film over either a weighted or spring-loaded roller, usually mounted on the platter column monitoring the film feed from the platter to the projector. When excessive tension builds, the roller is pulled such that it trips a microswitch or magnetic proximity switch, sending a "shut down" signal to the automation. Better systems use a "trolley" system to allow enough film slack to let the projector coast to a stop without tearing film or perforations.

Tension sensing failsafes are available from most of the major platter manufacturers (e.g., Strong, Speco) and from vendors like Kelmar and Avask.

Kodak still recommends always using a tension-sensing failsafe with polyester prints.

The other "fail-safe" is a film break detector, that usually also functions as a end of film detector. These will NOT protect against buildup up tension between the platter and projector.

Posted by Edward Jurich (Member # 1787) on 09-15-2003, 04:18 PM:

The platter has a payout failsafe using a tension roller that pulls up if the payout jams.
The projector has two ball bearing rollers that ride the edge of the film (both sides) located after the film exits the projector just above the takeup spindle. If the film breaks or slits, one or both of the rollers drop and stop the projector.

Posted by Chris Hipp (Member # 1788) on 09-15-2003, 04:55 PM:

tension sensing failsafes are also known as wrap detectors.

Posted by Carmine Occhino (Member # 1699) on 09-15-2003, 09:10 PM:

how much does one of those wrap detectors cost ?

Posted by Chris Hipp (Member # 1788) on 09-15-2003, 09:21 PM:

Im sure it would vary depending on your equipment, but it is a pretty simple device so it shouldn't be too expensive.

[ 09-16-2003, 12:29 AM: Message edited by: Chris Hipp ]

Posted by Gordon McLeod (Member # 33) on 09-15-2003, 09:29 PM:

I depends a bit on the make of plater it will be fitted on?

Posted by Carmine Occhino (Member # 1699) on 09-15-2003, 09:33 PM:

neumade xetron 5 platter

Posted by John Pytlak (Member # 331) on 09-16-2003, 10:01 AM:

Here is the "Optional Platter Failsafe" (NXPFS) made by Neumade:

http://prosites-clementsx.homestead.com/platters~ns4.html