Film-Tech Forum ARCHIVE: Converting Elmo 16-CL to silent speed

This is topic Converting Elmo 16-CL to silent speed in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011377

Posted by Ed Halter (Member # 6999) on 01-21-2013, 12:35 PM:

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?

Posted by Robert E. Allen (Member # 1351) on 01-21-2013, 02:23 PM:

Ask the guys over at 16mmfilmtalk.com.

Posted by Scott Norwood (Member # 30) on 01-21-2013, 08:08 PM:

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.

Posted by Jonathan Froes (Member # 5861) on 01-21-2013, 08:56 PM:

change your pulley size

www.mcmastercarr.com

Posted by Ed Halter (Member # 6999) on 01-21-2013, 10:42 PM:

hey guys, thanks for all those suggestions. Pulley size...that's an interesting idea.

Posted by Joe Elliott (Member # 4006) on 01-22-2013, 12:17 AM:

Jonathan, excellent link. One of the most organized product web sites I have seen. If only Grainger would organize their web site that way!!

Posted by Jonathan Froes (Member # 5861) on 01-22-2013, 01:53 AM:

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.

Posted by Stephen Furley (Member # 1277) on 01-22-2013, 08:28 AM:

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.