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How to wind the spring of a Bolex B8?

Bolex B8 spring

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#1 Joel Pierre

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Posted 01 May 2013 - 11:36 AM

I have completely disassembled a Bolex B8 to clean and lubricate it.
 
After complete reassembly the camera, I have a problem with the spring: I can not wind the spring that only a quarter turn before it is blocking, and of course, the mechanism works only on of this quarter turn spring wound (about one second, which is very little).
 
CEbsoSpVTN8_engrenages.jpg
 
I have certainly done something stupid, but I do not know what. Could it be the relative position of the gear spring should be respected?
 
But which one? Anything else?

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#2 Dom Jaeger

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Posted 01 May 2013 - 07:45 PM

Hi Joel,

 

the limit gears on the winder side of the motor in your photo look OK, you don't need to worry about any gear alignment when the motor is fitted.

 

When winding the motor up the motor body stays stationary, only the inner shaft connected to that central gear turns (and the limit gear next to it). They look OK, nothing blocking the teeth, so the only other cause I can think of is that one of the uni-clutches in the winding mechanism might have been put in backwards (upside down). There is one under the winding handle which allows the handle to slip when turned counterclockwise, but grips and turns the motor shaft when turned clockwise. The other is a large diameter but very short spring fitted under the circular winder plate which allows the plate to turn clockwise but not counter-clockwise.

 

If the winder handle turns freely counter-clockwise then that clutch (under the little plate with 3 screws on the winder side) is OK. I'd then check the spring under the winder plate, which has to be accessed from under the motor. I wrote a guide to servicing pocket Bolexes, which has photos that might assist you:

 

http://cinetinker.bl...-bolex-d8l.html

 


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#3 Simon Wyss

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Posted 02 May 2013 - 02:05 AM

Dom has it perfectly right. One little thing to remember is that Paillard springs are mounted pre-tensioned. One should not be able to wind up completely which would risk to tear the spring from its attachment to the barrel, and also should the spring not unwind fully in order to take constant torque to the mechanism.

 

Therefore one needs a spring winder and a torque spanner.

 

Of course, you can remove the spring stop. You’ll be able to go further winding and have longer takes. If the mechanism is well maintained. An important detail of such pimping is removal of the spring (CAUTION !), fine-grinding its edges, and polishing it entirely, unless its convolutions might not slip well. Once replaced in the barrel, free of burrs, particles, and grease, you lubricate it with graphite.

 

But since one can wind the spring while shooting (tripod) one better restores the original state.


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#4 Joel Pierre

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Posted 02 May 2013 - 03:09 AM

 

I wrote a guide to servicing pocket Bolexes, which has photos that might assist you:

 

http://cinetinker.bl...-bolex-d8l.html

 

 

Thank you for the answer.

 

I specifically follow your step by step guide to disassemble and reassemble the Bolex. Everything seems to be consistent.
 
CEckf0dLrJA_triskell.jpg
 
The mechanism locks as it should. But spring seems relaxed. It only works for a second:
 
 
 

 


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#5 Joel Pierre

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Posted 02 May 2013 - 03:10 AM

One little thing to remember is that Paillard springs are mounted pre-tensioned. Therefore one needs a spring winder and a torque spanner.

 

 
I also think that the spring is relaxed. It is very low. As unfortunately I do not have the necessary tools to restore power, I fear that the camera is ruined.
 

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#6 Dom Jaeger

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Posted 02 May 2013 - 07:42 AM

Don't worry Joel, I doubt that your camera is ruined.

 

You can check the spring motor when it's removed from the camera by holding it firmly and turning the square-ended shaft clockwise with a shifter or spanner. It will wind the spring inside and want to force the shifter back around (so be careful). One rotation should be enough to show you that the motor itself is not jamming.

 

The limit gear stops the spring from completely unwinding, when it hits the stop the motor is a bit relaxed because it is nearly unwound. After winding about 11 rotations the other long tooth of the limit gear again hits the shallow valley and stops the motor being overwound.

 

If the motor is able to be wound with a shifter, the problem is in the winding mechanism. It looks like the uni-clutch for the winding handle is OK but what about the clutch for the winder plate? That's the big spring that wraps around the round plate and has a hook that fits into a slot in the body. If that is in upside down it will bind when you try to wind up the motor. The round plate should rotate clockwise but bind anti-clockwise.


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#7 Joel Pierre

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Posted 02 May 2013 - 11:39 AM

I turned the square axis of the spring with a wrench. There is very little resistance and when I release the wrench, the return spring does a quarter turn (regardless of the number of revolutions of the axis).
 
The spring winding mechanism seems properly mounted.

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#8 Dom Jaeger

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Posted 03 May 2013 - 12:09 AM

 

I turned the square axis of the spring with a wrench. There is very little resistance and when I release the wrench, the return spring does a quarter turn (regardless of the number of revolutions of the axis).

 

 

OK well that sounds like the spring has indeed broken or detatched from one of its anchors. Simply removing the motor from the camera wouldn't have caused that, it was probably already on its last legs and running it a few times has finished it off. Unusual for an 8mm Bolex motor (since the limit gear protects them from overwinding), but perhaps some corrosion got in there.

 

It's odd that initially you couldn't wind it more than a quarter turn but now it keeps turning without actually winding up.. but maybe the broken mooring inside was jamming it and has now worked free.


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#9 Simon Wyss

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Posted 03 May 2013 - 12:48 AM

Check with Bolex about a replacement spring or buy another B 8 (from me). I also have two H 8 Reflex for sale, one with the Vario-Switar EE.


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#10 Joel Pierre

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Posted 03 May 2013 - 01:59 AM

I have other Bolex cameras. I had used it for low-value, to learn how to disassemble and lubricate other. What I feared was that the removal of the mainspring does entail such inconvenience.
 
Thank you for your advice.

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#11 Simon Wyss

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Posted 03 May 2013 - 05:47 AM

Il m’était un plaisir.


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