Film-Tech Forum ARCHIVE: Christie M35 Shutter assemblies and blades dont fit

This is topic Christie M35 Shutter assemblies and blades dont fit in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Frank Dubrois (Member # 3042) on 05-04-2006, 07:19 PM:

This is an ongoing problem that I can't seem to figure out. We bought a NEW shutter assembly and tried to put the blade on the shaft. The blade gets about 1/2 way on then wont go any further. Sometimes we get lucky and a shutter blade will actually slide on without a problem, but 99% of the time, they do not fit. I'm wondering if this is a common problem, and if so, how do you go about getting the shutter blades to fit on the shaft? The only solution I found is to lightly grind the shaft until the blade slides on...when it does, everything works fine, but I don't see why a used (or new) shutter blade shouldnt just slide on to a new (or sometimes used) shutter assembly. All parts are at room tempature. I beleive the blade needs to easily slide onto the shaft in order to time these machines. I've run into situations where I needed to replace the shutter belt, and have been unable to time the machine because the shutter blade will no longer loosen up so I can time it. Any professional insight would be greatly appreciated!!

Posted by Mark Gulbrandsen (Member # 72) on 05-04-2006, 08:48 PM:

"I'm wondering if this is a common problem, and if so, how do you go about getting the shutter blades to fit on the shaft? "

This is not unusual and I've had it happen to me a buunch of times. Make sure that the clamping ears on the blade hub are seperated far enough to slide the assy onto the shaft. If the lamping ears seem to be ok but it still won't slide in place then reaming the hole so it's diameter is true to its length is the correct way to get it to fit. You can get a small adjustable reamer for this purpose but excercise extremely great care in doing this with a drill... and take almost barely minute cuts with the reamer until it just slides onto the shutter shaft freely. Ideally reaming any part should really be done in a lathe.

"The only solution I found is to lightly grind the shaft until the blade slides on...when it does, everything works fine, but I don't see why a used (or new) shutter blade shouldnt just slide on to a new (or sometimes used) shutter assembly."

Used blades have had the hub sections slightly distorted (squeezed together) to clamp it onto the shaft... so it can be this distortion that causes the problem... sometimes. Sometimes a batch of parts can miss a certain production stage such as reaming or the tooling (reamer) becomes worn and is not caught in time... alot of parts can get made with that worn tooling and they slip through QC, or are just sent on their merry old way.

NEVER grind any shaft for a part to fit in place. Shafts such as this are precision ground over their length sometimes to tolerances of .001". Grinding a shaft is as taboo as using WD-40 and Lubriplate in a booth!

Hey, Another Film-Techer told me recently that you really work at a theatre in Wisconsin [Wink]

?

Mark

Posted by Frank Dubrois (Member # 3042) on 05-04-2006, 09:07 PM:

I thought the blades were balanced in some way because of the small indentations drilled, so I hesitated to ream the blade side at all, but rather go for shaft.... It all works.

Posted by Mark Gulbrandsen (Member # 72) on 05-04-2006, 10:31 PM:

The shutter hub is balanced to take into consideration the single blade. Reaming removes infinitesimal amounts of metal and won't affect the balance at all.

Mark

Posted by Gordon McLeod (Member # 33) on 05-04-2006, 10:35 PM:

It is not unusual to find many shutters difficult to slide on
as mark said the clamp on used ones can be crimped in as can there be build up on the shaft

Posted by Monte L Fullmer (Member # 2797) on 05-05-2006, 02:42 AM:

..many times I replaced those single blade shutters, I would find the metal buildup on the shaft to where I had to lightly knock that build up off to get the new shutter on the shaft.

..and had to spread the pinch the ears a bit to get them on the shaft..

Another tip to look out for as well..make sure that the screws that are tapped into the lead counterweight that locks down that blade are tight - remember coming across a few that the blade was wobbling some during the rotation and found the counterweight screws had worked loose.

A good maintanence procedure with these Christies...

-Monte