Barrel Bound Mainspring?

[mlschlot]

I was reading an old article in the May, 1996 edition of the "Horological Times" discussing mainspring inspection and maintenance. In the article one of the faults listed in the mainspring inspection topic was "barrel bound". However, the author never explained what this meant. I've never heard this term used before, but assume they're referring to a situation where mainspring coil edges rub the confines of the barrel. Consequently, the edges of the spring coils are pinched and abraded (steel versus brass?) from rubbing against the barrel cap and great wheel.

I repaired a French movement once where someone had replaced the time train mainspring with one slightly too wide for the barrel. The clock would run very erratically because the edges of the spring coils were rubbing and binding. I was surprised the barrel cap didn't pop. However, I can't really say the edges of the spring were damaged; it was just too wide. More often, I run across coned mainsprings that bind and rub against the barrel cap as a result of being forcefully pulled from the barrel with pliers instead of a mainspring tool being used. Is that considered barrel bound?

 

[Grant Perry]

I wonder if it refers to a “set” spring that has lost its tension (terminology?). When you remove it and it doesn’t un-coil?

 

[tracerjack]

“Barrel bound” sounds like it means exactly what you have stated, that the barrel itself somehow binds the mainspring. That would happen to a mainspring too wide for the barrel and also to one that has become coned.

 

[shutterbug]

Or perhaps one where the barrel hook broke and/or the end of the mainspring? That way they are hard to remove from the barrel.

 

[mlschlot]

I wonder if it refers to a “set” spring that has lost its tension (terminology?). When you remove it and it doesn’t un-coil?

I've had clocks with that issue too. I encounter it mostly with 400 Day clocks that quit if the suspension breaks or some other issue occurs after a full wind. After the event, the clock is stuffed in a box and put on a shelf to gather dust for the next 40 years or so. I always referred to this phenomena as "spring memory" but I like "set spring" too.

 

[mlschlot]

Or perhaps one where the barrel hook broke and/or the end of the mainspring? That way they are hard to remove from the barrel.

Technically that would work as "barrel bound" too. The article used the term as if it was part of the established horological lexicon. I'm just hoping to verify if my understanding of the term is basically correct.

 

[mlschlot]

The article referred to the term as a condition to inspect the mainspring for after it was removed from the barrel. The same as you would inspect for rust, pitting, cracks, damaged "hole ends", etc., etc. If the edges of the spring were abrading against the barrel cap or great wheel, I'm not so sure the edges of the spring would necessarily show anything. Maybe you could feel a snag or something while cleaning or greasing the spring. I've tossed plenty for little nicks in the edge I interpret as a crack just starting, or that cause a trip to the Band-Aid box. It's an automatic revenge toss to the recycle box if there's blood on the floor.

 

[Lynsey]

Please refresh my memory...what is a mainspring tool?

 

[mlschlot]

Please refresh my memory...what is a mainspring tool?

A Bergeon, Ollie Baker, Webster (my favorite), lathe, or some other tool used to help safely remove and install mainsprings.

 

[Lynsey]

Oh, how embarassing. Mainspring tool. I have always heard it called a mainspring winder. I bought the Ollie Baker and love it. Had to wait 3 months for it, but it was well worth it. See what happens when you take time off from here? Cobwebs in the cranium. Thank you.

 

[mlschlot]

They certainly are! I stand by calling it a tool because they do so much more than just winding and unwinding mainsprings. Definitely on my "indispensable" tool list.