Reel Arm Bells on 5in cores vs 8in cores?

[Tj Hopland]

Interesting to hear about the belt system. I had never seen a complete one but now know why I have seen a multi groove pulley a few times. The ones I had had to adjust a few times appeared to be newer than the Hatke ones with a larger bell. On those the ball track mechanism was contained within the bell and made out of some phenolic material. I think those were the ones where the adjustment screw was fairly coarse and it seemed like just touching the screw made minutes difference. I have no idea if that set had been modified or was maybe badly worn, either of those issues could have effected how the adjustment worked.

There was another system that may have been a regional thing supposedly invented by a local operator. The shaft had octagon(ish) cam on it and there was spring loaded rocker arm follower that rode on the cam. The clapper was attached to a spring steel shaft and to the rocker arm. I assume that a combination of the length of the shaft and weight of the clapper made the osculation tunable. At lower speeds the clapper would just wiggle around and not touch the bell but at the set speed I assume it hit a resonate harmonic sort of thing where it would strike the bell. A nice thing is it would start fairly quiet and grow in volume as the speed increased.

Oh and for those that are wondering why the advertisements talk about 'no contact' and 'no scratching' is that what appeared to be a very common system was a pivoting arm with a fairly tiny brass roller at the end of it that rode on the film. On the back of the magazine was another arm with the clapper so when the diameter of the roll got small enough the arm would fall down and the clapper would strike the bell. The roller wasn't a full width thing with some sort of bearings it was maybe 2mm wide and just spun (if it was clean) in the end of the arm. The bonus design feature was this thing rode right in the middle of the frame, well I guess the film technically so the scratch was off center of what was projected. Before you removed the empty reel you had to stick your fingers in there to flip the arm back to the top so the empty reel would clear the arm to be removed. When you loaded the next reel you had to remember to flip the arm back down onto the film so it could do its thing.

[Ryan Gallagher]

Oh and for those that are wondering why the advertisements talk about 'no contact' and 'no scratching' is that what appeared to be a very common system was a pivoting arm with a fairly tiny brass roller at the end of it that rode on the film. On the back of the magazine was another arm with the clapper so when the diameter of the roll got small enough the arm would fall down and the clapper would strike the bell. The roller wasn't a full width thing with some sort of bearings it was maybe 2mm wide and just spun (if it was clean) in the end of the arm. The bonus design feature was this thing rode right in the middle of the frame, well I guess the film technically so the scratch was off center of what was projected. Before you removed the empty reel you had to stick your fingers in there to flip the arm back to the top so the empty reel would clear the arm to be removed. When you loaded the next reel you had to remember to flip the arm back down onto the film so it could do its thing.

Yeah our museum worthy Brenkert 80 Supreme in storage still has similar alarms fitted... although at least this version seems to fall clear of a standard 15" reel... but you'd have to lift it when putting the new one on.

IMG_5788.jpg

More photos of the rest of the projector here:
https://www.film-tech.com/vbb/forum/...dental-museums

[Brad Miller]

That alarm design on the Brenkert above is a great way to put emulsion scratches right down the center of the film. I've seen it happen.

[Scott Norwood]

For 70mm DTS, it should be easy enough just to note the timecode at the reel changes. At least the XD20 has a timecode display on the front panel. Obviously, this won't wake up a sleepy operator, but it provides a quick way to look up and see how much time is left on the reel, assuming that the film has already played at least once and someone has noted the times.

[Ryan Gallagher]

For 70mm DTS, it should be easy enough just to note the timecode at the reel changes. At least the XD20 has a timecode display on the front panel. Obviously, this won't wake up a sleepy operator, but it provides a quick way to look up and see how much time is left on the reel, assuming that the film has already played at least once and someone has noted the times.

Haha, there is the catch "Already played at least once", as we typically only play them once. But that is a good thought on the ones we tend to play every year such as 2001.

If one is paying that much attention one can also just look at how much film is left on the reels (as we did this season), but the timecode method does allow for you to set a phone alarm if one is that worried about missing it.