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Author
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Topic: Elmo 16-CL pulley dimensions
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted January 05, 2010 07:51 AM
Hi Dino,
I have both types of 16-CL, and have the pulley dimensions for you, but I am at the office at the moment, and the measurements are at home.
I'll post the answers for you here as soon as I get hold of them.
______________________________
OK! Now arrived home, so here are the dimensions of the pulleys you asked for. As you may have read in a previous post, I have turned down one of my motor pulleys on a lathe to give me 16fps on our 50Hz mains supply - but that's another story - it's just in order to let you know that I took all pulley measurements while I was doing the job, using a vernier calliper. All measurements are across the flanges of the pulleys - NOT across the valleys.
EUROPEAN VERSION - 50Hz only, but can change film speed:
MOTOR PULLEY
18fps = 24mm. diameter
24fps = 30mm. diameter
SHUTTER SHAFT PULLEY
18fps = 63mm. diameter
24fps = 58mm. diameter
USA VERSION - 24fps only, but can change supply frequency:
MOTOR PULLEY
50Hz = 30mm. diameter
60Hz = 26mm. diameter
SHUTTER SHAFT PULLEY
50Hz = 58mm. diameter
60Hz = 61mm. diameter
You can easily see that the 24fps setting for both versions uses the same size and ratio pulleys for the 50Hz supply.
I hope this helps. I'm interested in your reason for wanting this information.
Cheers,
[ January 05, 2010, 09:45 AM: Message edited by: David Pannell ]
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted January 07, 2010 02:41 AM
Hi Dino,
A little confusion here, I think.
The 20fps results from simply using my USA version of the 16-CL on its 60Hz setting, on our 50Hz electricity supply. This results in the shutter shaft turning at the equivalent of 20fps, as there is a fifth difference in frequency and therefore a fifth difference in speed.
I achieved the 16fps speed simply by turning down the 60Hz section of the USA version motor pulley from 26mm. dia. to 21mm. dia.
I then purchased a new USA pulley from Richard Patchett, as the European pulley is as rare as hen's teeth.
Thus, the EU model remains unaltered, giving 24fps and 18fps.
The USA model gives 24fps and 20fps with the standard pulley, and 24fps and 16fps with the turned down pulley.
I hope that makes the procedure clear.
If you are wanting to achieve 18 or 16fps with your USA machine, as well as retaining the 24fps, I'm afraid your only option is to turn down the motor pulley in the correct ratio.
You need to bear in mind that it is important to maintain the correct ratio between the motor and shutter shaft pulleys, otherwise you will have to adjust the motor position as well, whenever you wish to change speed, as the belt would be either too tight or too loose on one or the other settings.
Having said all that, it isn't a difficult task, and certainly well worth the effort if you wish to screen silent films.
Good luck, and please let me know if I can be of any further help.
BTW, if you swapped the belt to the 50Hz position, you would get 24fps + 20% = 28.8fps!!!
THEREFORE, my considered recommendation would be to purchase a new spare pulley from Richard Patchett, (so there is no chance of ruining the stock pulley), and turn down the larger diameter to give 24fps - this would be the normal 50Hz position, and then turn down the smaller diameter section to give 18fps.
Although the calculation of the correct ratios would seem the way to go, and you can do this initially, as you get nearer to the correct size, then a more reliable method would be to do it practically by turning down a millimetre at a time, and use a stroboscope till you get the speed exact - that's how I did it!
Best regards,
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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So is there NO way to alter the speed of a US elmo in the US?
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