Film-Tech Forum ARCHIVE: Christie Filmgate Adjustment

This is topic Christie Filmgate Adjustment in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Nicholas Simmons (Member # 2489) on 07-24-2004, 12:23 PM:

What is the correct way to adjust the lateral guide rollers on a christie filmgate? I have "the tool" but I have found it very difficult to get them set so both the top and bottom rollers will turn with the film running. When I get one right though, the image looks very good.

Posted by Mark Gulbrandsen (Member # 72) on 07-24-2004, 06:52 PM:

I use a digital height gauge resting with the trap on a granite tool plate. the gauge is a good place to start though and then tweek with the height gauge so they are both exactly the same height. I've also found that if either band is slightly cocked that it can also cause the filkm not to contact one roller or the other.

Mark @ CLACO

Posted by Richard Hamilton (Member # 321) on 07-24-2004, 07:00 PM:

Mark,
Every Tech should carry a slab of Granite in their tool kit!! [Wink]

Posted by Phil Hill (Member # 371) on 07-24-2004, 07:09 PM:

Richard... [thumbsup]

That's too funny! [beer]

>>> Phil

Posted by Will Kutler (Member # 770) on 07-24-2004, 07:20 PM:

What Mark is speaking of (granite) is a "must have/standard item" in any machine shop.

Ya, those Christie traps can be a pain to adjust. I also used the Lock-Tight that Christie recommended, but it still managed to loosen up over time.

Personally, I cannot stand Lock-Tight. I prefer using correct locking type hardware. Companies like Berg have set screws with
self-locking inserts.

Do be careful of Christie gates where the threads for all four set-screws can be a loose-tolorance fit, resulting in in a problem with those set-screws wanting to loosen up and drop the jewels on the floor!

Posted by Phil Hill (Member # 371) on 07-24-2004, 07:22 PM:

Ya know Will... I HATE when **my** jewels fall on the floor...

>>> Phil

Posted by Richard Hamilton (Member # 321) on 07-24-2004, 07:39 PM:

Will, how many techs have access to a machine shop? In all of my experience servicing theaters, I've only been to one shop, and that was to make a new part. I don't recall any granite there either!

Posted by Richard Fowler (Member # 893) on 07-24-2004, 08:17 PM:

Granite stones need not be big...I use a 6 x 8 inch granite to check small parts.

Posted by Richard Hamilton (Member # 321) on 07-24-2004, 08:36 PM:

6x8x? And how heavy? Still not something I would carry with my tools.

Rick

Posted by Ron Yost (Member # 1850) on 07-24-2004, 08:59 PM:

1/4" plate glass is very 'flat', too. [Smile]

Ron Yost

Posted by Richard Fowler (Member # 893) on 07-24-2004, 09:01 PM:

Weighs about 10 - 12 pounds. Something that I don't carry too often. Have used it in my cinematography work in addition for mechanical issues in cinema equipment. The old Mega Systems had a fab machine shop....too bad it is no more.

Posted by Richard Hamilton (Member # 321) on 07-24-2004, 09:09 PM:

Now,for me the Megasystems shop and building is just a memory. All good, and I will vacation in St. Augustine often!

Rick

Posted by Will Kutler (Member # 770) on 07-24-2004, 09:17 PM:

Granite or cast iron surface plates are norms in shops and are used as reference surfaces for precision inspection. They come in a variety of sizes, from 6 X 8 through huge tables.

No, this would not be a tool-box item.

Posted by John Pytlak (Member # 331) on 07-24-2004, 09:24 PM:

Precision alignment:

http://catalog.starrett.com/catalog/catalog/PLH2.asp?NodeNum=25399

http://www.newport.com/Support/Tutorials/Vibration_Control/v2.asp

Posted by Brad Miller (Member # 2) on 07-24-2004, 10:57 PM:

Nicholas,

The tool from Christie works amazingly good for as simple as it is. Here is what you do.

Place the tool up against the edge of the trap. Make sure there is a tiny bit of clearance between the outboard flange of the lateral guide roller and the tool.

***Be careful not to lose the jewels!!! When you are wanting to move the lateral guide roller toward the inboard side, loosen the inboard allen screw only about 2 rotations, then turn the outboard allen screw inward until it starts to snug up, then go back and loosen the inboard allen screw about 2 rotations and repeat. (Obviously you do this in reverse if you need to move the lateral guide roller toward the outboard side.) Also, make SURE you do this over something to catch those jewels in! A lid to a banker's box works amazingly well, as would a reasonably sized Tupperware tub. Just something where the jewel cannot drop and roll 1000 miles away and hide itself in the event you accidentally loosen one of the screws too far and let it fall out.

Getting back to where I left off, loosen the inboard allen screw 2 turns so that you can move the outboard allen screw inward until the lateral guide's outboard edge starts pressing up against the alignment tool. What you want to do is turn the allen screw until you see it pressing the alignment tool to where it is starting to cock it at an angle, so it is no longer 100% flush. Then back off just a tiny bit until you see the tool come back to rest flat and square up against the film trap. (You have to be holding the alignment tool with pressure into the side of the trap so that your pressure acts like a spring against the guide roller that is pressing into it. Yes, this is very hard to put into words without pictures.) Now immediately tighten the outboard allen screw's locking screw.

Next you want to tighten the inboard allen screw until the lateral guide roller can no longer spin. Find that magic spot to where it just BARELY starts to cease spinning when gently spinning the outboard edge by hand. Then back off 1/8 of a turn exactly and lock down the inboard allen screw's locking screw. At this point the lateral guide roller is not only aligned via the tool, but there should be zero lateral movement of the outboard flange. If there is side to side movement, it will translate to the screen...hence the 1/8 of a turn trick.

Repeat for the other lateral guide roller.

Posted by Mark Gulbrandsen (Member # 72) on 07-25-2004, 12:15 AM:

"No, this would not be a tool-box item."

No, its an in the van tool that resides near the small arbor press that I also carry and weighs about the same as the press does.
There are very few dealers out there with a complete shop, but there are a few. We just added a 13X48 lathe to our arsenal of machine tools primarily to produce our own lens bushings for the DP-70's. Even the new Kinoton produced bushings are pretty bad. We plan on going right down to 70.6 mm with just the single piece bushing. One run of 40 bushings pays for the cost of the lathe.

Mark