Film-Tech Forum ARCHIVE: Damaged Chain Wheel

This is topic Damaged Chain Wheel in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Chris Byrne (Member # 1563) on 03-25-2003, 05:32 AM:

I was adjusting a couple of feed sprockets today for correct endplay when to my horror I discovered a fibre chain wheel had lost 3 of its teeth (on bottom feed sprocket shaft.)

It have only just noticed this, however this cinema has been giving me grief with higher Digital readings of late.

Besides a possible head wrap, is there anything else that could have caused this?

Posted by John Spooner (Member # 1565) on 03-25-2003, 09:13 AM:

Chris, we have had several fibre gears loose teeth over the years on the Kalee machines, the last time was the fibre shutter drive gear.
Unfortunately fibre gears are a weak point in the gear train and are designed to act as a safety device when the mechanism binds, the gear strips so much greater damage does not occur.
They get weaker as the years go by and are susceptible to gear backlash or too fast start-up.
Unusual for the take-off gear to strip as it really only has the take-up tension on it, so in your case it must have had a great amount of film tension for a time or a sudden fierce jerk which weakened the fibre teeth and they broke off. Polyester film being very strong will take the high tension whereas the old acetate would break before damage occurred.
When the old input fibre gear on the Kalee machines played up, it was common practice to replace it with a nylon direct replacement.
Please keep me informed of any results, my regards to you and Douglas. John Spooner. Adelaide SA.

Posted by Stan Gunn (Member # 554) on 03-26-2003, 03:09 AM:

Hi Guys
Kalees have metal takeup chain sprockets, unless it has been changed.

May be able to help you with a sprocket, contact me direct if you wish.

Regards
Stan [beer]

Posted by Douglas Curry (Member # 1485) on 03-26-2003, 02:17 PM:

/me points Stan to the 'Finding Friends' thred in the Film Yak section.. [beer]