Film-Tech Forum ARCHIVE: Help me with my friggin' shotty aperture plates!

This is topic Help me with my friggin' shotty aperture plates! 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=006086

Posted by Christian Volpi (Member # 2370) on 04-22-2004, 10:08 AM:

Does anybody know of a quick and easy way to cut aperture plates? I'm too cheap to buy a bunch of plates and practice.

Posted by Aaron Sisemore (Member # 145) on 04-22-2004, 11:13 AM:

First, make absolutely sure that your circuit permits you to do your own aperture work!

If they do, get yourself a 'nibbler' cutter (I believe you can still get them from Radio Shack) and a LaVezzi aperture file (absolutely necessary- Don't try cutting plates with any other standard file!). Find some old plates (you can usually find some in the booth somewhere) and experiment with the nibbler and the file- Remember that it doesn't take much cutting to show a huge difference on screen, especially with Scope!!)

Once you are satisfied that you can do this without too much destruction, get some new plates for the job (necessary if your present plates are overcut), run a loop of RP40, and begin cutting!

Warning: If you aren't careful, you can get yourself into big trouble in a hurry with the nibbler, but for working with 'pinhole' plates or cutting a scope from a flat plate its a gigantic time saver. Do all the final cutting, or any small jobs with the aperture file.

-Aaron

Posted by Gordon McLeod (Member # 33) on 04-22-2004, 11:33 AM:

The problem have with a nibbler is often they will slightly distort the brass blank.
I tend to always start with a pinhole plate and use a burr in a dremmel tool to open up to the approximate size then a augur bit file
Gordon's RIDICULOUSLY LONG link
and for the corner a needle file

[ 04-22-2004, 02:54 PM: Message edited by: Adam Martin ]

Posted by Ian Price (Member # 14) on 04-22-2004, 12:13 PM:

Note to self:

When cutting plates, you are removing material that is opposite what you see on the screen, because the image is reversed in the lens. So if you need to remove aperture material from the top of the screen on the right side. You need to file material from the bottom of the plate on the left side.

I have to stick my tongue firmly in the left side of my mouth and screw up my face to get this right. [uhoh]

Posted by Randy Stankey (Member # 64) on 04-22-2004, 12:57 PM:

Stand next to the projector, facing the screen and grab the plate with your left hand. Pull it out and swivel your hand/arm toward you and set it down on the surface in front of you so that the side of the plate that is supposed to face the screen now faces you.

Doing this, you have flipped the plate from left to right so that what you saw on the screen is the same as you see on the plate.

Now, all you have to remember top and bottom. If you are working on the top edge of the picture the bottom edge of the plate is already in position for you to work on it. If you are working on the bottom edge of the picture, just remember to give the plate a vertical flip.

Once you do this enough times it becomes automatic and you hardly have to even think about it.

Posted by Trevor Bailey (Member # 75) on 04-22-2004, 11:06 PM:

Before getting anywhere near aperture plates, I feel it is imperative to check your lamphouse and image alignment on the screen. There are too many variables to go into here, but in a nutshell:

-light should be centered on your aperture
-lamphouse/projector should be centered on the screen
-verify true screen center left-right (measure)
-with RP-40 and lenses ensure center (left-right)
-do not move anything between cutting flat and scope

I don't know how many places I've found it necessary to adjust lateral alignment when changing lenses. Some even need vertical alignment when changing lenses.

Initial alignment and aperture cutting is not something for an untrained person. Get a qualified tech to show you how, so that you won't have all the "little" problems.

[ 04-23-2004, 04:14 PM: Message edited by: Trevor Bailey ]

Posted by Rick Long (Member # 213) on 04-23-2004, 12:22 AM:

RULE #1: Do the alignment first. LAST THING YOU TOUCH IS A FILE.

Posted by Phil Blake (Member # 2012) on 04-23-2004, 10:43 AM:

I agree with the others , go very slowly and gently with the cutting , It is hard to undo, Our plates in one cinema were over cut , we had to use a hammer and a parallel punch to spread the brass again , then file it back , Big Job.

Posted by Frank Angel (Member # 248) on 04-24-2004, 07:24 AM:

Ian said,

quote: Ian Price
When cutting plates, you are removing material that is opposite what you see on the screen, because the image is reversed in the lens. So if you need to remove aperture material from the top of the screen on the right side. You need to file material from the bottom of the plate on the left side.

Do you have any idea how difficult this can get for those of us with dyslexia?! [Eek!]

Posted by John Hawkinson (Member # 1135) on 04-24-2004, 03:41 PM:

So, what is special about Lavezzi Aperture files? How are they different from, say, #4 cut swiss files or needle files? Maybe someone could post a picture?

--jhawk

Posted by Gordon McLeod (Member # 33) on 04-24-2004, 03:45 PM:

I think they are awkward in shape and over priced
I use the auger bit for most of the cutting and needle files in the corner

Posted by John Walsh (Member # 168) on 04-24-2004, 05:26 PM:

Aperture files usually have one side smooth, or "blank" so you can file one side of an opening, but the blank side will not file the other side of the opening.

Posted by Floyd Justin Newton (Member # 1316) on 04-24-2004, 07:52 PM:

WHATEVER you do, take your time and don't rush!! I've seen more
kids gouge out plates to the point where new plates had to be
bought. And they wonder why they aren't paid [bs]

!

fjn
Local 294 Ret.