This is topic LeVezzi POSI-TROL sprockets L4CS31??? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Steve Beverly (Member # 4540) on 12-28-2008, 10:56 PM:
 
Does anyone know what projector this fits:

LeVezzi POSI-TROL sprockets part number L4CS31
 

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Posted by Mark Gulbrandsen (Member # 72) on 12-29-2008, 10:22 AM:
 
Ask the seller for dimensions, O.D, Bore, Etc, then we amy be able to help... thats not a currently made sprocket. I will also look in an old LaVezzi catalog and see if it's listed.

Updayte: They are holdback sprockets and have a 5/16 bore and a half inch counterbore at the end... not sure what projector they are for... These cannot be used on the intermittent.

Mark
 

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Posted by Steve Guttag (Member # 268) on 12-29-2008, 12:25 PM:
 
The L4CS31 will fit:

Simplex E7 lower feed
Century projector lower feed

According to the LaVezzi chart.

Now the L4CS31, being a holdback sprocket are no longer being made. There was a period of time where most projector manufacturers had different sprockets for holdback (check your Century, Simplex or even Noreleco manuals). The diameter of a holdback sprocket was slightly less (on the order of 7-mils for a 16-tooth sprocket).

Most, if not all projector manufacturers now use the same sprocket for both duties and the "feed" sprocket size is the one used. Thus, the L3CP31 can be used in place of the L4CS31 (though not really vice-versa).

Steve
 

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Posted by Richard Fowler (Member # 893) on 12-29-2008, 12:55 PM:
 
When film stock was nitrate and life of a print was several years in the marketplace; the different diameter sprockets tolerated film shrinkage.
 

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Posted by Steve Beverly (Member # 4540) on 12-29-2008, 09:09 PM:
 
AH, just my luck. I was hoping they'd work on a Super (I want to go all Positrol). However, there's a guy selling 3 of these on 35mm Film Collector dot com for 25 bucks each new in the box, new old stock from 1960 which I though was a decent price though I could be wrong. They fit 5/16ths shafts to answer Mark's question.

Since they won't work on my SuperSimplex, maybe one of you E-7 or Century guys could use one or two of these. However for some unknown reason it won't allow me to post the link but I'm sure you can easily find it, it was posted there on the 26th. I don't know this guy so I don't know his reputation. I would, of course, therefore take any precautions you deem appropriate before buying which is just common sense.
 

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Posted by Jeremy Weigel (Member # 4208) on 12-29-2008, 10:43 PM:
 
Same ones being sold here on the forums perhaps?

Link
 

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Posted by Steve Beverly (Member # 4540) on 12-30-2008, 11:37 PM:
 
Yep, dat's da guy.
 

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Posted by Christopher Seo (Member # 7) on 12-31-2008, 12:42 PM:
 
Steve,

What's the reasoning behind a smaller diameter (would you say, 'tooth pitch'?) for the holdback sprocket only?
 

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Posted by Mark Gulbrandsen (Member # 72) on 12-31-2008, 01:39 PM:
 
I believe it put one more tooth in contact with the perfs and hence less strain on the film itself. With Estar this is less of a factor but if you've ever run old brittle acetate you then know what I mean. The downside of shorter pitch sprockets is that they wear out quite a bit faster. When I had the sprockets made for my VistaVision projector I had the pitch made just a tiny bit less than normal. This proved to me much easier on the film than a standard pitch sprocket would have been.... That custom 32 tooth VV intermittent sprocket is also a Positrol!!

There are several articles on the pitch of projector sprockets in International Projectionist Magazine a long time ago that explained the trade offs involved in sprocket diameter vs. noise vs. sprocketwear vs. film wear and so on. WIll have to dig and see if I still have those mags around...

Mark
 

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Posted by Steve Guttag (Member # 268) on 12-31-2008, 07:52 PM:
 
I don't think the diameter is enough different to get you an extra perf. Furthermore...even the AAII had a "holdback" sprocket...with 32-tooth, the diameter is so much larger, the odds of getting an extra perf are even more slim. I know I tried an NOS "H" sprocket and it sung to the high-heaven...regardless of take up tension...including when feeding an AW3 platter. So I'm not quite sure what the "benefit" of it was supposed to be.

Steve
 

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Posted by Edward Jurich (Member # 1787) on 12-31-2008, 07:55 PM:
 
I have the sprockets. I was given these in about 1960 from an operator because I assume they could no longer use them with mag prints that were coming to local houses. I thought being so old they might be useful for someone. Actually, I changed the post to will donate if you can use them for the cost of priority mail. I hate to just throw them out.

Here is what they look like


 

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Posted by Steve Beverly (Member # 4540) on 01-01-2009, 12:25 AM:
 
Now I'm REALLY upset that they won't fit a Super
 

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Posted by Robert Throop (Member # 61) on 01-01-2009, 09:31 AM:
 

quote: Edward Jurich

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I was given these in about 1960

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quote: Steve Guttag

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So I'm not quite sure what the "benefit" of it was supposed to be.

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quote: Robert Throop

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I didn't think the Positrol was introduced until the mid seventies about the same time as the VKF.
Bob

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I believe you are correct Robert. The wide Posi-Trol tooth uses many attributes from the VKF tooth.
 

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Posted by Edward Jurich (Member # 1787) on 01-01-2009, 10:27 AM:
 
UPDATE...it appears I found a home for these, hope they can be used. LaVezzi never got back to me, guess they are too busy for non-business e-mail.

I am 99.99% sure I got these sprockets from the Hiway theater in Chicago at the same time I got some used Brenkert sprockets from the operator. And that would have been either 1960 while I was in high school or after I got out of the Air Force. I was still visiting the operator at the Hiway when I got out of the Air Force so it could have been closer to 1965. That was a long time ago but for sure before 1969. But anyway, if the general opinion is these are useless I will toss them. I am trying to clear out 50 years of junk that somehow seems to have gotten out of hand

Here is some information

LaVezzi - POSI-TROL SPROCKETS

LaVezzi - VKF SPROCKET

I filled out their contact form and asked when they first manfactured these. If they say 1975 I am going to wonder where I got them

Well, I got my response and it would appear I got these sprockets at a later date than I thought. I can not imagine where because I was out of contact with any theater in the 70's and I do not recall getting them in later years. Someone must have broken in and placed them in the box with the other sprockets

Edward,

Sorry it took a while to respond to your inquiry, we were doing our inventory this week.
We made this part over 20 years ago and cannot find the drawing to get a particular date
for you. We believe it was the 70s or 80s.

Hope this helps,

Regards,
Carol Steen
LaVezzi Precision

[ 01-08-2009, 12:30 PM: Message edited by: Edward Jurich ]
 

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