Film-Tech Forum ARCHIVE: Foil Sense Rollers Not Conducting

This is topic Foil Sense Rollers Not Conducting in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Edward Jurich (Member # 1787) on 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.

Posted by Jonathan M. Crist (Member # 413) on 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 ]

Posted by Edward Jurich (Member # 1787) on 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.

Posted by Ron Yost (Member # 1850) on 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

Posted by John Pytlak (Member # 331) on 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:

Posted by Paul Mayer (Member # 355) on 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]

Posted by Edward Jurich (Member # 1787) on 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.

Posted by Randy Stankey (Member # 64) on 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?"