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03-5-2020 11:49:13  #1

Hermes Rocket drum spring broken, how to remove drum?


Drum spring is snapped. I am prepared to fix (cut notch into spring) the spring as soon as I can remove the drum.
I've removed all casing, and still can't remove drum.  
It just spins on the screw and is in a pretty tight space to work in.

Any ideas?

Throw up into your typewriter every morning. Clean up every noon - Raymond Chandler

10-5-2020 14:16:47  #2

Re: Hermes Rocket drum spring broken, how to remove drum?

Usually these are secured by a nut on the back side of whatever is supporting the spring housing. The screw is used to adjust tension, and the nut is used to affix both tension as well as the whole unit to the chassis or carriage support rail. Often I think there are proprietary tools to get to this tiny space. I just re-cut a slot in the spring of my Underwood 18; getting it back on and properly tensioned was the real pain. Next time it breaks, I'm going to have to look for a source of 5mm wide spring steel.
While you have that spring out, clean everything with a good solvent then make sure it's dry. I use a liquid vehicle/ dry graphite spray for spring motors in motion picture cameras with spring motor clockwork. The dry graphite allows the spring coils to slide. Oils will often attract dirt and also cause the coils to bind when the motor sits for a while. Eventually, oils will polymerize and then you get coils stuck together leading to breakage. I learned this from a Paillard-Bolex trained motion picture camera technician who told me that oiled spring motors often prematurely break.
I'm the FNG here though, but the spring attachment points on typewriters is what I've seen so far in the last month of having 11 different machines apart. Social distancing has me working on typewriters, motion picture, and still cameras, when I should be finishing my master's thesis and culminating project presentation.
Phil Forrest


12-5-2020 17:34:01  #3

Re: Hermes Rocket drum spring broken, how to remove drum?

Phil, do you have a link to the graphite you use?  I think quite a few of us may be interested in that product.


12-5-2020 17:51:40  #4

Re: Hermes Rocket drum spring broken, how to remove drum?

The graphite is, dare I say, made by 3 in 1. It is their specialized dry lock lube. It does not leave a waxy residue at all, I've found after testing. I was taught to use dry flake graphite in spring motors that had gotten gummed up with 40 years of oil plus graphite. That just creates a paste that binds stuff up. If a spring motor has been completely flushed, it needs new graphite. I see this in overhauling Bell and Howell 70 series motion picture cameras. In the last several years of working on these weekly, I've never seen a broken mainspring, just ones locked up with tar from never being properly cleaned and lubed. A friend of mine in Michigan supposedly has a 70DR with a broken mainspring but I'm still doubtful. Anyway, the liquid vehicle is really effective at soaking between the coils and properly lubing the spring. It's reasonably volatile and evaporates pretty quickly, so a few applications while running the spring is necessary for a complete coating. With a carriage spring, it's not nearly as tensioned as a motion picture camera which runs for ~50 seconds on a single wind, but the carriage spring receives far more cycles and is never allowed to relax, so it can be more prone to breakage.
Phil Forrest


12-5-2020 17:55:05  #5

Re: Hermes Rocket drum spring broken, how to remove drum?

Good to know, thanks Phil.


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