Film-Tech Forum ARCHIVE: My film gate won't close right....Plus filing a plate

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Posted by Richard Greco (Member # 2032) on 05-07-2004, 09:53 PM:

I am running Century SA's

I try to close the film gate, the one with the big knob, and it doesn't seem like there is any tension holding the gate to the film. The knob was loose and I tightened it. It still doesn't close tightly. Could it be the spring? If so, any ideas on how to change it. Should the part be in the booth?

Second Question...
How can I file a scope plate down? Do I need to being a file in the booth?

Thanks in advance for any advice.

Richard

Posted by Chris Hipp (Member # 1788) on 05-07-2004, 10:04 PM:

typically filing would require the use of a file. Do what you want but I would suggest that if you must file your own plate, use a new one so if you mess it up you at least still have whatever you had before.

Posted by Randy Stankey (Member # 64) on 05-07-2004, 10:21 PM:

The gate closing spring in the Century can be a real bitch to install correctly. It loves to make you think it's going in the way it's supposed to then suddenly, SPROING!!

If you have removed the knob it's a sure thing that the spring has been sprung or even lost. You'll have to check to see that there are no lost/broken parts then reinstall them.

It'll take a bit of patience to do it right.

Before you file a plate be sure you have the right plate in the right projector. Every projector/lens/screen combination demands its own custom-filed aperture plate. It's easy to mix them up.

If you file on a plate before you verify that it is the plate that's supposed to be in that projector, technically, you are screwing up two projectors!

Posted by Mark Gulbrandsen (Member # 72) on 05-07-2004, 11:12 PM:

If you follow the easy to do instructions in the SA manual for srtting the spring you will find it very easy to do. Also if the spring is bent in the slightest then replace it as it will make re-setting it alot more difficult. Today when I was re-assembling a JJ in the shop I installed a new spring as the old one didn't even look the way it should. Took less than 30 seconds to get the new one in with the proper tension. When its set properly the gate should snap shut when you tap in on the large knob with your hand. If it doesn't snap shut there may also be a build up of crud around the gate tube that needs to be cleaned up. This requires removal, disassembly and cleaning of the gate operating mechanism. Again follow the manual and you'll find it to be VERY easy. Be sure to set the correct clearance (1/4") when you re-install the assembly back in the machine.

If you have a booth full of unmarked plates be sure the correct plates are at each machine and then file a series of small V notches along the outside edge to identify which screen they belong to. This is better than engraving it somewhere on the face of the plate plus you can look at it when its in the machine and tell if its the correct one or not. Use a LaVezzi file to do the job or an equivelent file without searations along the narrow edge. Its literally the only file I use, its got the proper serrations for the hardness of brass the plates are made out of so the job can go quiclky, but you can also still maintain control of the file very well. I can do an entire 8 plex worth of plates in alot less than an 8 hour day with just the one file, curved screens included!

Mark

Posted by Gordon McLeod (Member # 33) on 05-08-2004, 03:13 PM:

"Second Question...
How can I file a scope plate down? Do I need to being a file in the booth?"

I think it would be safe to say you don't. If you don't know what you are doing and have the experience then you are treading on dangerous ground
Also it is probably against company policy to alter there equipment with out the supervising engineers permission

Posted by John Foley (Member # 1183) on 05-10-2004, 03:04 PM:

Do you mean the gate barrel has no tension, or the final resting place of the gate does not provide tension on the bands?

If you close your gate and try to push back the barrel manually does it give easily?

I would think that if it did, you would be very lucky not to have focus issues (perhaps fiction and weight are enough to hold it in place).

If it does give (lack’s tension) sounds like the spring (I find them a pain to change as well).

If it does not give, is the gate meeting the trap well, or is it falling short? Is something (ie the trap being misaligned and the gate rails hitting the trap film guides) blocking the gate closure? Is gate support bracket to far toward the screen (has 2 sets screws on top and 2 on bottom).

Posted by Scott Norwood (Member # 30) on 05-10-2004, 03:07 PM:

Suggestion: don't take apart the knob (with the spring inside it) until you have a _new_ spring. Installing a new spring isn't too difficult, but re-installing an old, worn-out spring can be almost impossible.

Also, leave the gates closed overnight. In theory, the springs will wear out more quickly if you leave the gates open.

As for the plates--don't cut the existing ones unless they are truly horrible. If they're even halfway decent, wait until you get some new ones (or old ones) to work on. You really should have a loop of RP40 (aka PA-35) test film as well. Century plates should be about $6 each, so there's no need to risk one that might be good (or good enough).

Posted by Richard Greco (Member # 2032) on 05-10-2004, 04:35 PM:

Update

I called my tech and he talked me through installing the new spring. It was surprisingly easy!!! I haven't had a problem since.

Posted by Jack Ondracek (Member # 1466) on 05-11-2004, 10:12 PM:

...from Scott:

quote: Scott Norwood
Also, leave the gates closed overnight. In theory, the springs will wear out more quickly if you leave the gates open.

If this is true, which is best?... leave the gate open and take the tension off the bands (on a curved gate), or close the gate, keep the bands under tension, but relax the spring?

I don't recall where I learned it, but I've cleaned my gates & traps & left the gates open overnight on every machine I've run for a lot of years. I haven't noticed any effect one way or another. I always open the lateral guides on my Simplex sound heads to keep flat spots from forming, though it interested me that you could not do the same on a Motiograph SH7500 and it didn't seem to matter.

Posted by Gordon McLeod (Member # 33) on 05-12-2004, 09:40 AM:

The method I ask operators in theatres I service to follow is
remove the gate and then close the mechanism that way both parts are left relaxed overnight
(Personaly a good beer would be more relaxing but I save that for myself)