This is topic VKF vs. "Fox" sprockets for mag prints in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Phil Hill (Member # 371) on 02-09-2009, 03:21 PM:
 
Hey yous hardware/film brains out there...

I have four 35mm projectors and they all have VKF sprockets. I'm looking to keep one or two of them thar machines for my home screening room and sell off the others.

My bottom-line question is: Will the VKF sprocket set work for 35mm 4-track mag prints or should I install my 2 sets of "Fox" sprockets?

If the Fox sprockets are required, would they be OK for non-mag "standard films or would I have to play the change-game for each type of print?

Thanks!
 

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Posted by Robert Minichino (Member # 3495) on 02-09-2009, 03:29 PM:
 
I have no actual experience here, so prefix all of the sentences with "in theory."

The VKF (as opposed to VKF-2 or positrol) sprockets will fit into the Fox/CS perfs on unshrunken film, but if the film has shrunk significantly (and for anything with CS perfs this is likely) you'll probably shred some film. The CS sprockets will work fine on normal KS perf film with a little extra stress on the sprocket holes.
 

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Posted by Phil Hill (Member # 371) on 02-09-2009, 03:44 PM:
 
Thanks for the info, Robert.

How can I tell if I have VKF vs. VKF-2/Positrol sprockets?

Thanks!
 

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Posted by Robert Minichino (Member # 3495) on 02-09-2009, 04:59 PM:
 
Calipers? The Lavezzi site has excellent dimensioned drawings for their sprockets.

http://www.lavezzi.com/QA/LavSprocket.html
 

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Posted by Tony Bandiera Jr (Member # 2365) on 02-09-2009, 05:54 PM:
 
Phil the positrol will have one tooth set visibly wider than the other, you don't need calipers to tell the difference.

I must respectfully disagree with Robert..the VKF's are LESS likely to damage shrunken film..I have some ancient mag stock (a test loop) where the LENGTH has shrunk, but it tracks just fine on VKF equipped machines.

In fact, in the literature lavezzi sent out when the VKF series was introduced, one of its selling points was better control and safer handling of shrunken or damaged film.
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-09-2009, 08:44 PM:
 
Should be no problem at all and the CS perfs are actually ALOT stronger then KS perfs are. So the use of VKF teeth on CS perfs is actually beneficial. For the sprockets to actually damage film the stock would have to be drastically shrunken and it would be shrunken to the point that it may not even wind on the taske up reel. I had a MAg/Optical print of Sand Pebbles once that was so badly shrunken that the filum wouldn't wind properly on the reel.. but on screen it played reasonably well using VKF's.

Mark
 

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Posted by Dick Prather (Member # 1136) on 02-10-2009, 03:15 PM:
 
Phil, The VKF sprockets were designed to run mag film with no problems but I had some shrunken mag that would not run properly on X-L sprockets. I replaced all my VKF sprockets with new CS sprockets and have had no problems since.

We ran all film on CS sprockets for years in the theatres. If you have lots of shrunken film I would recommend changing sprockets,
Dick
 

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Posted by Tony Bandiera Jr (Member # 2365) on 02-10-2009, 06:48 PM:
 
I've heard Phil has a lot of shrinkage...
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-10-2009, 06:51 PM:
 
Tony, Thats just from Phil swimming in the Ocean!
 

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Posted by Jack Theakston (Member # 4484) on 02-11-2009, 08:32 AM:
 
I've run all of my mag prints on VKF sprockets and never had a problem. They're also quite gentle on shrunken KF/BH perfs, too.
 

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Posted by Steve Guttag (Member # 268) on 02-11-2009, 11:36 AM:
 
We've definitely experienced some VKF sprockets not working with shrunk CS perf prints. Those clients of ours that run 4-track have CS sprockets too (now).

Steve
 

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Posted by Phil Hill (Member # 371) on 02-11-2009, 02:00 PM:
 
Thanks to all for your comments.

quote: Steve Guttag

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Those clients of ours that run 4-track have CS sprockets too (now).

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