Spring Steel : Making A Spring For Bolex Crank Handle

ic-racer

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The spring steel keeper on one of my Bolex cameras broke. This is very annoying as the handle will not stay put when not in use. It flaps around.

 
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ic-racer

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This is the part I need. Not so easy to find. This image is from a "Sold Out" page.

 
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ic-racer

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To make the spring I'll use a feeler gauge. I'll heat it red hot so I can bend it. Then I'll polish it and then heat it only enough to turn blue. That will turn it into a spring.

The original spring measured about 0.3mm, so I used the 0.011" blade from this set.

 
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ic-racer

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Heating the piece red hot (did not show well with the flash).
 
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ic-racer

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Bending it into rough shape. It will break if you try to bend it without doing the prior step.

 
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After polishing with a wire brush (does not show well with flash). Polishing removes the black residue from the previous heating so the color change of the next step is evident.

 
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ic-racer

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Heating just until it turns blue. Now it is a spring.

BTW, when I make parts like this I err on the side of 'just a little too big' as the parts can be filed smaller if needed. In this case it fit just fine, so I left it this size.

 
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ic-racer

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Works gerat! The spring grabs a pin on the side of the camera. Now my handle stays in place!!

 

eli griggs

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Don't forget K&S Precision Metals, sold in hardware stores. Hobby shops, Crafts stores, Home stores sells Phosphorus Bronze Spring metal in a sheet.

This can also be bought online.

Congratulations on making your repair and on the tip to use feeler gage steel, I know I'm not the only one that's found one or more of these sources of donation material from old toolboxes and yard sales, etc.
 

eli griggs

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Was this steel annealed after the first or second tempering treatments?

It'll be a shame if it breaks because it's too brittle from no annealing being done.
 
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eli griggs said:
Was this steel annealed after the first or second tempering treatments?

It'll be a shame if it breaks because it's too brittle from no annealing being done.
Click to expand...

Entire books have been written on annealing. In this case, the flame heating steps outlined above reliably make the long-lasting spring steel. It won't reliably work if the steps are not followed exactly. Ovens and quenching not needed due to the tiny size.
 

David Lindquist

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Very nice work. How did you cut the feeler gage to begin with? Shears? A very neat cut.
And from my own experience drilling a nice round hole in thin metal like that isn't easy.

Hardening, tapering and annealing of steels is a bit beyond my skill set.

David
 
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ic-racer

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The metal was thin enough to get a clean cut with "tin snips." (You can see the tip of them in post #7 above.)

The location for the hole was first center punched to keep the drill bit from wandering.
 
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