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Loop end mainspring slipping off winding arbor

clarke

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Oct 25, 2009
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I can't for the life of me get the arbor hook to catch on the inside of the mainspring. I've done it successfully before, but not this one. I bend and crimp and reshape until I'm blue in the face, with no success.
Are there any tricks of the trade to make this easier? Or it just more trial and error efforts?
Or should I just use a brand new spring and toss the old one?
c.
 

bruce linde

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you should post photos... and make sure you're trying to put it on the right way. if there's enough of an edge, you should be able to catch it.

i've been learning that there's no such thing as looking too closely... got magnification? :)
 

shutterbug

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Yep. The hook might be the problem. They are not all that hard to make, and you might be fixing to learn how :)
Don't overlook the advise to look at things closely. If you have the spring turned over, it will never catch.
 

R. Croswell

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Sometimes the problem is the 2nd. coil. There must be some space between the 1st. coil and the 2nd. coil. The hook need to go through the hole, not just start into it. If the 2nd. coil is flat against the 1st. then the hook can't go through the hole far enough to catch.

Picture of the arbor and hook without the spring would help. If the "hook" is more like a peg with a flat top, then sometimes filing the trailing edge so the hook slants upward toward the leading edge, and slightly undercutting the leading edge will held "suck" the hook into the hole in the spring.

RC
 
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kevin21

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Though I'm not the original poster, I thought I'd use this thread since it has posts that I used in trying to get my winding arbor to catch. Alas, I have had no luck. See my pictures and words below..

I have tried many times and definitely made sure I am winding it the right way. I have tried filing the catch as was suggested in another thread with pictures that totally helped. I think I have the catch in a decent shape. I have tried, with both a screwdriver and various pliers (even bought some round-nosed pliers) to re-shape the inner coils to be tighter on the arbor. None of it seems to work.

I have tried putting the arbor on while the spring is uncoiled and while it is in a clamp. I have tried winding in my winder and also tried putting the spring into the movement, containing the second wheel and winding. In all cases, the arbor slips with very little tension.

No idea what to do...
Kevin

Photo Jan 17, 4 35 40 PM.jpg Photo Jan 17, 4 40 19 PM.jpg Photo Jan 17, 4 41 19 PM.jpg
 

bruce linde

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in the three photos, the spring is the wrong way around... yes?

also, (with the caveat that i am a hobbyist and not a pro) i have had good success grabbing the inner end of a mainspring... maybe from the halfway point of the hole and toward the tip... and bend it inward slightly so that it's not a smooth arc like the one pictured, but more like this... check the slight bend near the tip, with the top white line.

Photo Jan 17, 4 41 19 PM.jpg

if you're working with the spring pictured, the hole seems too far back from the tip to me.... i think it should be more like where the top white line is as opposed to how much extra tip you have on yours... that might be part of the problem.
 

Willie X

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The inner loop should be round and slightly smaller than the arbor. A good bit of force will be required to slide the spring onto the arbor. Willie X
 
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kevin21

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Thanks for your input. I will try your ideas tomorrow. And yes, I didn't think about the orientation of the spring when I took the picture, my bad... I was so focused on trying to get good pictures :)

Willie, I have had the loop quite small to the point where I couldn't hardly get the arbor in, but I will try again...
 

Willie X

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When you force it on, try to make the hook go through the little gap at the start of the second turn, then rotate the hook into the hole. This gap is very clear in bruce's last photo.

Note, when all is well you should be able to see the tip of the hook sticking up slightly above the edge of the inner hole. Read RC's post #3. If not, something is not right.

Willie X
 
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kevin21

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So, I have been able to get the spring completely wound on my winder (with the arbor connected). I have left it this way. I saw in a previous thread where shutterbug said to completely wind the spring once one gets it to catch so that it will be "shaped". How long should I leave it this way. I have done this (wound it up tight and then immediately unwound it) other times I got it to connect, but no shaping happened and as soon as I loosened it into my c-clamp and put it on the movement it failed to stay caught when I tried winding it tight there.
 

Willie X

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If you wound it up tight, you don't have to wait to unwind it, or capture it in a clip. I usually run them up tight and back down a couple of times. It's rare for one to uncatch. :oops:

Willie X
 

kevin21

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Aug 30, 2021
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As soon as I went to unwind it using the winder, it uncaught and completely unraveled. I didn't have the c-clamp on, but no harm was done. This is what has been so frustrating for me. I have been through this at least 10 times, maybe even 20. I get it to catch, I wind it up, but then at some point later when I try to unwind or rewind it, it slips. This gives me no confidence that this is going to work long-term in a clock. I'm not sure how to get that confidence...
 

Willie X

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The hook looks odd but the shape looks like something that should work.

I think your spring may not be properly annealed at the inner end, or maybe the spring is not flat where the hook fits.

Can you see that the hook goes completely through and above the hole's top edge?

Willie X
 
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kevin21

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The hook is .0385" above the arbor, but...

When I went back to the winder (if you can imagine I left it in disgust after the last slippage), the catch had no slipped, the spring had broken!!

So, now I guess I have to get a new mainspring. Is this something I have to measure? I know there are three items of concern; are those width, length, and spring strength? I am working on a New Haven movement from a Tambour No 81 clock. I believe the clock was made sometime in the 1930s or maybe as late as 1940. Is there some repository that would tell me the spring to use? The one that broke is the strike chain mainspring, hould I be replacing the time chain mainspring as well? Or do I just wait until it breaks?
 

RJSoftware

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The first few loops of inner coil should be annealed/softened. What I do is pull center coils out, back curl them, so I end up with about a foot of the inner coil sticking out at angle of spring body. By pulling inner end of spring out one side or other, bending the curl out, I have access to heat a good portion of the center loops to soften them.

I heat that section with propane torch till it turns dull red, usually about 6 or so inches. The extra is just to make handling easier. The mainsprings usually make a black skin of suit before turns red. I pull torch away slowly and count 30 seconds between advancing distance of torch to spring. Else simply removing torch causes instant air cool making spring more brittle. Small parts air cool instantly.

Then inner coils are compliant. I curl them back into place. I know people rightly get concerned over creating center cone from pulling out one side, but easily reversed by pulling out a touch other side.

When the inner coils are compliant they collectively wrap arround arbor creating a tighter grip.

Also to consider is the shape of mainspring punch hole. Usually I can get away with round one, but a rectangle is better.

You can heat the end and bend over to near flat. Think of folding paper in half. Then with metal cutting dremel wheel cut two parallel slits on folded end. Then grind out between.

Heat up again and unfold. Now you created a rectangular hole. The flat edge should grip better. Trim edges but don't go too thin. Also don't overwork as metal will lose strength the more you bend it
 

shutterbug

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Kevin - When a job gets to a point where frustration sets in, it's usually because you are overlooking something simple. Try reversing the springs. If the problem follows the spring, try a new spring. If the problem follows the arbor, you have a bad hook.
And double check the spring orientation. In your pics the spring is upside down. You mentioned that you had noticed that, but always double check.
 

Elliott Wolin

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Novice here, but FWIW, I once had a lot of difficulty getting a spring to catch on the hook on a clock I got pretty cheap. Eventually, after many attempts at bending the spring where it should catch the hook, I finally got it. Not sure how it got bent so far out of shape in the first place, though.
 

kevin21

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Thanks for the swap idea shutterbug. That's a good troubleshooting step! Unfortunately, as I said in my last post, the spring I was working on snapped about 2-3 coils from the center, so I have to get a new one. I will re-post my questions from there since it would appear no one saw them...

I guess I have to get a new mainspring. Is this something I have to measure? I believe the three items of concern are width, length, and spring strength? I am working on a New Haven movement from a Tambour No 81 clock. I believe the clock was made sometime in the 1930s or maybe as late as 1940. Is there some repository that would tell me the spring to use? The one that broke is the strike chain mainspring, hould I be replacing the time chain mainspring as well? Or do I just wait until it breaks?
 

Rob Martinez

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Yes, measure the length, width and thickness. Might not all be needed but good to know and have for comparison with the replacement you get from India.... However, now (after measuring length) might be a good time to do as mentioned above and heat, cool slowly, and cut another hole. Yes, it will not last as long between windings but it is a good use of the existing spring, good practice, and will help you best diagnose what may have caused the original problem: arbor [length, cut depth/angle], spring [bent too much/not enough], whole [size, worn], all three? It is also a good use of your time while waiting for the replacement to come in.
 

kevin21

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Thanks Rob for your thoughts. I have measured my broken spring and it appears to be 3/4" x .018" x over 96". Not sure whether it is 108" or 120". As far as a new spring, I don't have to order one. I inherited supplies from my step-father and have a couple of brand new springs (actually he passed away 20 years ago so they are at least that old but still in their original box and plastic wrap. I also have an old Gilbert movement of his, that looks very similar to the New Haven movement I am working on, that has what appear to be brand new springs on it. I plan to use those for now. At around $20 for new springs, I can't see going the spring-repair route since for me that would mean buying new tools etc. Hopefully my issue was with the spring that broke, but we'll see.
 

RJSoftware

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When repairing, avoid sacrifice. The sacrifice can often end up a better project than the intended. Acquisition is a peculiar mistress, in hindsight it's a marriage of Murphy's law and exploration. Just remember, original is the gold. I would never sacrifice a Gilbert anything for New haven.
 
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kevin21

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Not sure what to say to your comment RJ; I'm not smart enough to know the difference between Gilbert and New Haven, though I can say the spring I took from the Gilbert was pretty knew looking so was not anything original and it caught first time by my arbor so I was able to put my movement back together and have it run overnight on my test stand. Striking properly and keeping good time.
 

RJSoftware

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Not sure what to say to your comment RJ; I'm not smart enough to know the difference between Gilbert and New Haven, though I can say the spring I took from the Gilbert was pretty knew looking so was not anything original and it caught first time by my arbor so I was able to put my movement back together and have it run overnight on my test stand. Striking properly and keeping good time.
Well, alls well that ends well. But if you happen upon a sweet Gilbert case, no movement, then you'll know. No shame in what you did and congrats on a easy repair. Start looking for an empty Gilbert case, within same erra of your Gilbert movement and you got another nice clock. The mega sin in clock repair world is marriage. That's where you mix parts from different manufacturers. Main springs are forgivable, because they are soo similar. But a Frankenstein is a marriage in the extreme.

Imagine if someone decided to toss out the New haven movement and install a Hermle with Westminster chimes. The holes in back of case won't align, so they just make new ones. Then they decide it needs tubular bells, so they have to cut hole in bottom of case so hammer levers can strike tubes. But levers wont reach so they bend them to fit out hole and establish elaborate levers with cables that strike tubes. But the clock wont hang right so they chop top off a Grandfather clock and build a platform for the New haven to set on. I guess you can see where I'm going with this.
 
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shutterbug

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3/4 X .018 X 96 was a standard size used in many clocks of the period. Also a standard size to have on the shelf, so a bit of investigation might show that you already have one ;)
Most of us prefer to reduce the thickness to .016 and lengthen the spring to 105 when replacing to lessen the wear on the movement.
 

kevin21

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I will try never to build a Frankenstein clock...

And yes, shutterbug, I do have a couple of "new" (they are actually at least 20 years old but still in original packaging) mainsprings from my father-in-law's stuff that are the size you mention but decided to use the one from the Gilbert because it was easier to get at. As I said, the Gilbert's mainsprings look pretty new. I think it was a movement my sister-in-law used at a class about 10 years ago when she was trying to learn about clock repair. That's the reason it has no case.
 

Elliott Wolin

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I will try never to build a Frankenstein clock...
I once had to, depending on your definition of "Frankenclock."

My movement had broken parts so I purchased another movement that I thought was identical. When I mixed/matched parts to get one working movement it ran 30% too fast. I then realized the second movement was built for a different pendulum length (not sure if it was marked on the movements, but back then I didn't understand the markings on movements). Fortunately, the relevant gears from the original were usable so I swapped them back in, and it ran fine.
 

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