Film-Tech Forum ARCHIVE: Foil Sense Rollers Not Conducting

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Foil Sense Rollers Not Conducting

Author

Topic: Foil Sense Rollers Not Conducting

Edward Jurich
Master Film Handler

Posts: 305
From: Las Vegas USA
Registered: Jul 2003

posted 12-21-2004 10:49 PM

I'm trying to put some old foil sense rollers back into operation on a PRO-35. Problem is the rollers don't seem to be making contact with the shaft even though everything is metal. Using an ohm meter, the problem seems to be with the tiny roller bearings inside the rollers. Is there some sort of special lube for these things to make them conduct? There is room on the shaft for a small spring, I'm thinking of trying a light spring that would press against the rollers and the back of the shaft assemblys to make contact but still allow the rollers to spin.

| IP: Logged

Jonathan M. Crist
Jedi Master Film Handler

Posts: 531
From: Hershey, PA, USA
Registered: Apr 2000

posted 12-22-2004 12:13 AM

The roller bearings contain a conductive type grease which dries up. You have to replace the bearings with new ones which have the fresh grease. Kelmar has the rollers available in different sizes. They have a chart you can download to determine the size rollers that you need.

Had to do this on my system earlier this year.

[ 12-22-2004, 11:55 AM: Message edited by: Jonathan M. Crist ]

| IP: Logged

Edward Jurich
Master Film Handler

Posts: 305
From: Las Vegas USA
Registered: Jul 2003

posted 12-27-2004 11:52 AM

I was able to get the rollers working again by spraying "DeoxIT D5" into the bearings. It's a contact cleaner that cleans oxidation and lubricates. This is a very old can of this stuff I have and I believe it's now being manufactured by GC Electronics under the name "DE-OX-ID". This even worked on another machine where the ground is the sprocket and also didn't work. Spraying into the sprocket ball bearings got it to conduct again.

| IP: Logged

Ron Yost
Master Film Handler

Posts: 344
From: Paso Robles, CA
Registered: Aug 2003

posted 12-27-2004 01:12 PM

Um .. nope .. DeoxiT, ProGold, and other great contact/connector cleaning and lubricating chemicals are made by Caig Labs down in Poway (northern San Diego), Calif. On visiting their webpage I noticed their products are now available at RadioShack. News to me. [Smile]

One can also order directly from the Caig website. Good stuff! [thumbsup]

Caig Laboratories

I wouldn't want to bet how long those rollers will remain conductive if it's only the film residue of DeoxiT providing the conductivity, Ed. Not long, would be my guess. [Frown]

Ron Yost

| IP: Logged

John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 12-27-2004 01:31 PM

Conductive bearings:

http://www.entrenet.com/~stevend/equip/conduc_bear/conduc_bear.htm

quote:
I needed bearings that conducted electricity. My tests showed that if a bearing was not spinning then it had a low resistance. If I spun it, however, it had about 20Mohm resistance which is basically infinite.

http://www.thomasregisterdirectory.com/lubricants/conductive_grease_0018032_1.html

http://www.geocities.com/koneheadx/electricbearings.html

quote:
These photos below show how to construct electric bearings made from common roller-blade/skateboard bearings which are used in the place of motor brushes in order to send current in and out of the spinning rotor.

Shown below is a tube of conductive grease that replaces the silicone grease already in the bearings:

| IP: Logged

Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 12-27-2004 01:47 PM

I'll second the use Deoxit for cleaning electrical contacts. Been using the stuff since the early '70s (back when it was called Cramolin) for cleaning and/or treating broadcast TV camera cable and card-edge connectors. We always kept a can on the truck--it is indeed good stuff. The carrier in Cramolin actually attacked plastic, so it was reformulated as Deoxit.

Pay heed to their slogan, which is good advice when using this stuff, "The less you use the better it works." [thumbsup]

| IP: Logged

Edward Jurich
Master Film Handler

Posts: 305
From: Las Vegas USA
Registered: Jul 2003

posted 12-27-2004 02:35 PM

quote: Ron Yost
I wouldn't want to bet how long those rollers will remain conductive if it's only the film residue of DeoxiT providing the conductivity, Ed. Not long, would be my guess

I'll go back every so often and check, it was about 5 ohms across the rollers when I left. I'm wondering how long it'll last myself. I've used this stuff on switches that acted like they'd never conduct again and they lasted for a couple years after application.

| IP: Logged

Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 12-27-2004 11:01 PM

Just a spitball question...

If you have the kind of bearings that have the removeable shields which can be opened up, cleaned and repacked, could you add a bit of graphite to whatever grease you use to lubricate them? Could you thin the grease/graphite mixture with something (tricloroethane, turpentine or whatever) to allow it to get into the nooks and crannies better, thus allowing the conductive graphite to coat the internal parts?

I guess the question could be rephrased, "What do they put in grease to make it conductive?" And, "Couldn't you just regrease the bearings?"

| IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.