Film-Tech Forum ARCHIVE: Static and CNR

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Posted by Antonio Marcheselli (Member # 373) on 12-20-2003, 08:20 PM:

Hi everyone

I'm having some static problems, our humidity is too low (we are asking for hudifiers).
Some time ago I found that many of the CNR platters were not connected to the column. In other words, if I check the resistance between the platter and the CNR column there was NO conducibility (ALL the column are ground connected of course!). Usually there is conducibility when platter is stopped but NOT when it is moving. I solved this problem before putting a special grease, with graphit in it. It is not the best for bearing but since the platters are rotating very slow and the graphis is very small it is not a problem.
I started putting the grease with the help of a brush inside the bearing, without taking off the old grease. The result was time limited, after few weeks the problems came again.
So I disassembled a platter, I take off the bearings, I cleaned them from the old grease and I put only the new grease with graphit. The result was perfect but again, time limited.

I still have all of my platter nor ground connected while rotating.

Is there a chemical product that increase the conducibility and it is suitable for bearings?

Or any other suggestions...

Thanks!

Bye
A

Posted by Max Biela (Member # 1919) on 12-21-2003, 02:49 AM:

Hi Antonio!

What are your static problems?

What about the Projector? There must be a few rollers that are grounded so you should not have problems like popping sound.

The CNR Platters are very good in loosening sticking film layers, at least if they were not timed as stated in the manual (max. speed 60-65 RPM). If you set the max. speed to 35 RPM you get the best results because the platter still needs some time to ramp up to full speed. At 60 RPM, the film will wrap around the Pay out unit every time the arm gets pushed into full speed position. Normally if this happens there are the rollers around the Payout unit which protect the film from getting scratched, but if there is some film inside of those rollers which was pushed there by the other film layers wrapping around them, there is the danger for the film getting caught by the film which runs normally through the pay out unit... [thumbsdown]

Solution: Time the platters at max. speed 35 RPM and you wont have this problem.

Some time ago, Cinemeccanica sold an Anti-static "cleaner" (which was not a cleaner) for mounting it on (endless-loop) platters for working with polyester-film:

I would not use anything with graphit on the bearings, think of make up or take down of prints!

Max

Posted by Darren Briggs (Member # 1071) on 12-21-2003, 06:17 AM:

Are all your platters effected this way?
I find if a print becomes problematic, flip the take up orientation of the print, i.e. if you take up with the soundtrack up, on the next run, tkae it up with the soundtrack down, doing this for a couple of days normally settles the print down totally.
Overnight you can try the THX greenhouse trick.
Put a tub of water in the center of the plate and cover the print overnight. This can help loads in getting rid of static on the print. Ensure you leave a note on the plate, so that the next projectionist doesnt just rip the cover off and knock the tub of water over the print thought!!!

In combination with the flipping of the print the static should not cause a problem.

Darren

Posted by John Pytlak (Member # 331) on 12-22-2003, 01:28 PM:

Max Biela wrote:

quote:
Some time ago, Cinemeccanica sold an Anti-static "cleaner" (which was not a cleaner) for mounting it on (endless-loop) platters for working with polyester-film:

The unit in your photo seems to be a corona discharge ionizer. High voltage AC on needle points in the unit ionize the air, making it conductive, so that any static charge on the film has a conductive path to ground. Similar units are made by Simco, Kinetronics, Meech, and other manufacturers of static control equipment. Properly used, they are very effective in controlling static.

Posted by Max Biela (Member # 1919) on 12-22-2003, 02:12 PM:

Hi John!

Yes, but the Kinetronic also has 4 brushes to clean the film, the Cinemeccanica not. They are VERY useful with "old" polyester prints. Does anybody know if Cinemeccanica still sells these units? They look so nice on CNR platters [Razz]

I've also heard that Cinemeccanica sold a PTR-Cleaner along with CNR platters (I think they call it "Drypur or so..). Has somebody a photo of it? Were on the platter was it mounted?

Max

Posted by Gordon McLeod (Member # 33) on 12-22-2003, 02:23 PM:

Drypur rollers were a completely different animal to PTRs as they picked up dirt and it then migrated through the (silly putty) to the centre core. It did require that the plastic strips be placed on them when not in use to prevent them drying out
They were effecive at eliminating static and didn't complain about oil on the print
They were developed in Belleville Ontario Canada and drypur is still in business there

Posted by Max Biela (Member # 1919) on 12-22-2003, 02:38 PM:

Hi Gordon,

so if I understand you correctly you will have to change teh complete Drypur roller? Is there a website with more details about it?

Max

Posted by Gordon McLeod (Member # 33) on 12-22-2003, 02:44 PM:

The rollers required replacement when no more dirt could migrate through the material or if someone left the bands off and they dryed out
Last timeI contacted them it was
Restoration House Film group Ltd
Box 298 Belleville Ontario Canada
K8N 5A2
(613) 966-4076

It has been about 2 or more years since I delt with them

Posted by Antonio Marcheselli (Member # 373) on 12-22-2003, 05:14 PM:

John,

I have kinetronics on all of my platters. What do you mean with "properly use"?

I have so low humidity and the print is so warped that the kinetronics brushes cannot touch both sides of the print itself... [Frown]

Bye
A

Posted by John Pytlak (Member # 331) on 12-22-2003, 09:19 PM:

By "Properly Use", I mean that they are properly positioned to discharge the film in the most effective way, that the frames are properly grounded, that the corona points are kept clean and free of dust buildup, and that the high voltage power supply is monitored to be sure it is working well. If you are not careful, they can generate ozone.

Get yourself some evaporative humidifiers, capable of putting a few dozen liters of water vapor in the air each day. If the film is "warped" with curl, you really are much too dry.

Posted by Max Biela (Member # 1919) on 12-23-2003, 02:59 AM:

Hmmm.. some of our films are also warped because of our low humidity but we had NEVER any problems with static! We also have CNR platters, no kinetronics cleaner or other static control equipment, just 2 conductive rollers on the projector which are grounded - belive it or not - it helps.

Darren, what is the reason for flipping the print?

Max

Posted by John Pytlak (Member # 331) on 12-23-2003, 10:51 AM:

quote:
...what is the reason for flipping the print?

Film curl lends some rigidity to the film, so when there is some static cling, the print will tend to pull-in easier with one orientation vs. the other. Changing the winding orientation (soundtrack-up vs. soundtrack down) on the platter can sometimes help the print better resist pulling multiple laps.

Posted by Antonio Marcheselli (Member # 373) on 12-23-2003, 02:21 PM:

John,

Thanks for your suggestions, we clean the kinetronics carefully each week. Yes, the humidity is under 30%, is very low. We're asking our AC manufacturer for a humifiers systems.

About CNRs, I still think that a better ground can help preventing any static buildup. What do you think about Electrolube products? On Electrolube web you can found a grease that is conductive. I'm waiting for infos, I will try it on CNR's bearings.

Max, yours is a great idea. The Cinemeccanica recommended timing is good... when you have no static problems. I will try a slower settings asap... However, why does CNR are so simple... Why Cinemeccanica does not add some "smart" to the platter? For example: the platter that doesn't accelerate immediately at full speed when the payout arm is at the maximum position... And much more...

Bye
A

Posted by Max Biela (Member # 1919) on 12-23-2003, 02:44 PM:

Hi Antonio!

Yes, and the best is the Pot on the Pay out unit.. If you adjust it before the first show, the platter will turn slowly when its hot after some shows (and the arm is in the 0 RPM position..).

have you downloaded the video "Show West - Cinemeccanica"?
The Cinemeccanica guy said something like "When the arm gets pulled to the full-speed position, the platter will not run at full speed until the arm stays there for a little while and then it would ramp up to full speed when the platter wants it". I thought this IS a feature of the new CNR-N platters???

Max

Posted by Antonio Marcheselli (Member # 373) on 12-23-2003, 04:53 PM:

I'm used to ignore what Cinemeccanica's guys say... [evil]

Kidding.

I don't know, I just think that it should not be a "new" feature, it should be something present from the beginning. There is no need to be a genius to understand how important is a feature like that (and MANY others!).

(just saw the video: does the platter in the video has this new feature? Don't seem to me...)

Bye!
A

Posted by Antonio Marcheselli (Member # 373) on 12-24-2003, 02:32 PM:

addendum: I have the new "N" version and I didn't know!!!... It doesn't seem to me that the platter spins slowly until the payout arm is in the maximum position for a "long" time... The time the platter approach the maximum is connected to the phisycal time the motor needs to bring the platter to the maximum speed!!!

Perhaps older models does it worst!

Bye
A

Posted by Max Biela (Member # 1919) on 12-24-2003, 03:08 PM:

Hi Antonio!

no, the older CNRs do exactly the same.. even the old ones with black platter decks.. it seems to me that he CNR platters are getting more bad with every "update" they get! The oldest version of it seems to be the best (with black platters and the take-up elevator): They are far more robust than the new CNRs, had a felt brake for brake down (the new platters are turning free) and the electronic platter-brake brakes the platter FROM THE SIDE and not from the bottom of the platter so that they don't need this long "finger".

Does anybody know why cinemeccanica had changed the design?
Max

Posted by Antonio Marcheselli (Member # 373) on 12-24-2003, 08:58 PM:

I had the brake for CNRs at my previous job, we throw them away replacing them with a stong pair of gloves... I was used to Kinotons, CNRs seemed toys to me the first time!

I really believe that a new electronic control of the spin of the platter can made the CNRs MORE and MORE reliable and professionals.

I know that Cinemeccanica is developing a new core for CNRs. Perhaps the version "Z" will have a decent design!

John,
Do you believe that stand-alone humidifiers can be enough for a booth? Each projector has its own fan that send the exhaust on the roof and the AC system does not recycle the air, just put it in and not take it out. So the air changes continuously. Do you believe that some hi-performance humifiers can be enough or we are just wasting our money?

Bye
A

Posted by John Pytlak (Member # 331) on 12-29-2003, 01:50 PM:

I agree that the conditioned air being sucked up the stack to cool the lamps can make it hard to keep the humidity in the ideal range of 50 to 60 percent RH. But each humidifier can add a few dozen liters of moisture to the air per day, which can really help, even if you don't get to 50%. Note the new MIT lamphouse would allow using air from an OUTSIDE source to cool the lamp, so there are ways to reduce the load.

Posted by Dick Vaughan (Member # 540) on 12-29-2003, 02:42 PM:

Wow Gordon, Drypur are still around.

We tried the 35mm units out in the mid 80's with limited sucess and also tested them on our old Mk 1 IMAX reel units at the request of our friends at the plant in Oakville.

The rollers must have been a good 4" across and a pair were mounted on the top deck plate just before the final feed to the projector. After about 10 shows we started to find traces of the orange silly putty sticking to the rotor so the test was abruptly terminated [thumbsdown]

At that time of course the projector also had a discharge device and an air jet blowing ionised air back along the film just before it reached the input sprocket.

Both devices were found to have limited effect and were removed about 1990.

Posted by Gordon McLeod (Member # 33) on 12-29-2003, 03:25 PM:

The only problem I had with drypurr was don't let them make contact with fotoguarded prints that was a reactive big mess
We still have the hv static bar and the vacume cleaner as well as 2 ptrs on the input
We used the drypur on the 35/70 in theatre 1 to clean on rewind of our 3d 70 stuff
used to get about 3000 passes per print on them
also helped keep the dubber mag tracks clean

Posted by System Notices (Member # 2357) on 10-07-2005, 01:09 AM:

It has been 647 days since the last post.