Bolex EBM - Loop Formation Help

[Marko Steinberg]

Hi all,

 

I've recently acquired a new Bolex EBM in really good condition and decided to take the challenge of modifying it myself (battery, video assist etc). I'm glad the camera works and the motor is still running however, I've ran a few rolls of dummy film through it, and on all of them, the bottom loop is really short. Is this normal, or is it something I could potentially fix? I've attached an image but this is not from my camera, but is the exact same problem. 

The camera would in general probably need an overhaul, but trying to get at least one proper roll of film through it to see the results. hence why I want to address this issue as well. 

Any help is highly appreciated! 

[Dom Jaeger]

If the sprockets are not properly timed with the claw when auto-loading then when you open the loop formers the loop will shift up instead of being centred, causing a short lower loop. You can manually reposition the film after auto-loading to centre the loop, but to get it set up right a Bolex tech probably needs to adjust it. Basically the rotational position of the sprockets needs to be set so that as the film feeds through the perf gets immediately picked up by the claw and then by the lower sprocket. It can be tricky to get right. If you try to set it yourself be careful to maintain the sprocket height position as well, since they can sit higher or lower.

This is assuming the lower loop is immediately short after auto loading, and doesn’t shift after a while of running. That would be a different problem.

[Marko Steinberg]

Hi Dom!

Thanks a lot for the quick and detailed reply, it is very helpful. 

Unfortunately, it seems it's the latter problem that you mentioned. The lower loop is fine whilst the loop former is engaged, but as soon as the loop former is released, the top loop pulls up and the bottom one is automatically shorter. When I adjust the film by hand, as soon as I run the camera, the bottom loop becomes shorter. 

I'm assuming it's best if a Bolex technician has a look? Any other advice or info is highly appreciated. Thanks! 

[Simon Wyss]

If the claw is misaligned or damaged or there’s sticky grease to it, the film section between the loops doesn’t get transported correctly. I can take care of your camera.