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» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Converting Elmo 16-CL to silent speed

   
Author Topic: Converting Elmo 16-CL to silent speed
Ed Halter
Film Handler

Posts: 2
From: Brooklyn, NY, USA
Registered: Jun 2012


 - posted 01-21-2013 12:35 PM      Profile for Ed Halter   Author's Homepage   Email Ed Halter   Send New Private Message       Edit/Delete Post 
hey all

I have a couple of Elmo 16-CLs and I'm curious about converting them to silent speed, about 18fps. They're not the kind you can just switch the belts over.

Does anyone have any experience doing this and, if so, how?

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Robert E. Allen
Phenomenal Film Handler

Posts: 1078
From: Checotah, Oklahoma
Registered: Jul 2002


 - posted 01-21-2013 02:23 PM      Profile for Robert E. Allen   Email Robert E. Allen   Send New Private Message       Edit/Delete Post 
Ask the guys over at 16mmfilmtalk.com.

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 01-21-2013 08:08 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
I recently looked into doing something similar with a pair of Eiki EX-3500s. If you can live with 20fps as your "silent" speed, you can run them off of 50Hz AC with the belts set in the 60Hz position. There are a few different ways to do this, none of which is cheap: 60Hz AC->rectifier->inverter->50Hz is one approach; another is a VFD motor drive, though it is difficult to find one that will work on 120v single-phase power.

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Jonathan Froes
Film Handler

Posts: 26
From: phoenix az USA
Registered: Aug 2010


 - posted 01-21-2013 08:56 PM      Profile for Jonathan Froes   Email Jonathan Froes   Send New Private Message       Edit/Delete Post 
change your pulley size

www.mcmastercarr.com

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Ed Halter
Film Handler

Posts: 2
From: Brooklyn, NY, USA
Registered: Jun 2012


 - posted 01-21-2013 10:42 PM      Profile for Ed Halter   Author's Homepage   Email Ed Halter   Send New Private Message       Edit/Delete Post 
hey guys, thanks for all those suggestions. Pulley size...that's an interesting idea.

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Joe Elliott
Master Film Handler

Posts: 497
From: Port Orange, Fl USA
Registered: Oct 2006


 - posted 01-22-2013 12:17 AM      Profile for Joe Elliott   Email Joe Elliott   Send New Private Message       Edit/Delete Post 
Jonathan, excellent link. One of the most organized product web sites I have seen. If only Grainger would organize their web site that way!!

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Jonathan Froes
Film Handler

Posts: 26
From: phoenix az USA
Registered: Aug 2010


 - posted 01-22-2013 01:53 AM      Profile for Jonathan Froes   Email Jonathan Froes   Send New Private Message       Edit/Delete Post 
i've done a few mods to 16 projectors and always get pulleys at mcmastercarr. i'm not sure what's the reduction on the elmo but some projectors are 2:1 reduction. if you don't have timing pulleys on it i suggest you get it since there's no slipping.

your shutter shaft is a 1:1 ratio meaning 1 full turn per frame. at 24fps. 24hz(fps)x60secs = 1440 rpm. with that said your silent speed (18fps) at the shutter shaft should be 1080rpm.

you need to find out the size of your shutter pulley currently then check your motor pulley which should be smaller calculate the ratio between the two and that will tell you your motor speed from there you can get the right size pulleys for the silent speed.

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002


 - posted 01-22-2013 08:28 AM      Profile for Stephen Furley   Email Stephen Furley   Send New Private Message       Edit/Delete Post 
Take care that you don't overheat the film at the lower speed, particularly with black and white stock. The silver in the emulsion absorbs infra-red radiation much more than the dyes in colour stock. All of the silver, except for the sound track, is removed from colour print stock during processing.

Flicker may also be a problem with a standard 2-bladed shutter. Some projectors, e.g. certain models from Bolex and Graflex had shutters that could be changed from 2 blades to three, the bolex by moving a lever and the Graflex by moving a small locking tab on the shutter, allowing one of the blades to become two. I don't know if the Elmo had anything like this.

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