First Atmos repair, and a question or two

[shutterbug]

I've found an unusual issue in my first Atmos clock repair. The arbor hook for the inner spring coil is broken. I think I can fix that part, it's just unusual for such a weak spring to have the hook break. My curiosity is piqued by the extra inner portion of spring inside the barrel. What purpose does that have? It's not hard to put back in place, but it's odd.

 

[MuseChaser]

I promise to be of NO help at all... but if you'd be willing, able, and it's not too much hassle, I'd LOVE to see some pictures of whatever work you do on your Atmos. Still very gun-shy about taking the plunge into Atmosland ... but also still very interested in doing so.

 

[etmb61]

I've found an unusual issue in my first Atmos clock repair. The arbor hook for the inner spring coil is broken. I think I can fix that part, it's just unusual for such a weak spring to have the hook break. My curiosity is piqued by the extra inner portion of spring inside the barrel. What purpose does that have? It's not hard to put back in place, but it's odd.

Are you refering to the bridle?

Glossary - Mainspring - Auto Spring

Eric

 

[Ed O'Brien]

The bridle (small piece of mainspring) in the m/s barrel is designed to aid in maintaining the tension of a fully wound mainspring which is part of the Atmos design.

 

[shutterbug]

OK. Good to know. Most clocks don't use them. The thing kinda jumped out at me, so I hope I have it back in the correct way

 

[shutterbug]

I promise to be of NO help at all... but if you'd be willing, able, and it's not too much hassle, I'd LOVE to see some pictures of whatever work you do on your Atmos. Still very gun-shy about taking the plunge into Atmosland ... but also still very interested in doing so.

I'll see what I can do. I think I can do at least part of it They are not all that different from 400 day clocks, but letting the spring down is quite different, as is the winding system. I'm steeling myself for the task of putting the little chain back in position with the correct tension on it. You can take that big tank off without hurting anything and have a look at how it works. That might help you get the nerve up to try it. If you do that, put the tank in the freezer for about 20 seconds and see how the coil reacts. Fascinating.

 

[Ed O'Brien]

You need to find a readily available set of Atmos assembly instructions for basics, though they will not cover poising of the fork, putting the clock in beat, measuring the charge in the bellows, properly adjusting the chain, properly setting up the regulator adjustment, poising the suspension spring tube proper (extremely limited) lubrication, adjusting amplitude and a few other quirks that will prevent an Atmos from running.

 

[shutterbug]

Well, I think it's a success. It was a bit frustrating at times.
So here's the way I approached the repair:
First I let down the mainspring, removed the gas chamber, spring, and connecting parts and set them aside.
Then removed the dial, bezel and motion works. I could wiggle the dial and bezel out around the hands, so just left them in place.
Then the front plate came off, and the wheels were removed, then took apart the mainspring barrel.
Found the hook that was broken, and brazed it back in place.
Oiled the mainspring, and put the barrel back together.
Put the winding arbor back in place and tested it. All fine so far. Reassembled the main parts and oiled the pivots.
Now the fun part. The spring that the gas chamber manipulates has to be compressed and held in place at the same time the winding arbor is tensioned and held in place, and at the same time the chain is manipulated through the hole, put on the pulleys and locked in place with a little pin.
Whew! You need at least 6 hands! So here's how I approached it. First I compressed the spring and held it in place with two zip ties. Then I tensioned the chain, making sure it was on the pulleys, pulled it tight through the plate and held it in place with a push pin through a link in the chain. Now I could wiggle the end of the chain through the brass plate that the gas chamber pushes against, and hold the end link with a pair of forceps. Now I was able to cut the ties, letting the spring push against the plate and the forceps. With that part tensioned, I put the little pin through the second link (that's where it was when taken apart), letting it hold the tension from the spring as I removed the push pin and the forceps. Whew! Now I was ready to test the winding mechanism. I gave the spring part a push and watched the clock wind correctly. Three more pushes, and back together it all went.
Fun! But nothing requiring a doctorate in mechanical engineering I'm including some pictures of the progress. Enjoy - and I hope they help if you try it yourself! They are not in order, but if you note the picture names you'll figure it out. The clock is running in my shop right now, and I'll have to make sure it continues running and regulate the time.

 

[shutterbug]

Rethinking this, it might have been easier to just not hook up the return spring on the winding arbor until it was all together.

 

[KurtinSA]

I was thinking the same thing!

Kurt

 

[Jeff Hamilton]

Next time drop me a line. I would have gladly given you a new arbor. I would love to know how it got broken off. There is no real pull put against the hook, that spring is really light.

 

[shutterbug]

Thanks Jeff! Very kind of you. I'll definitely keep that in mind!
Yes, I was quite surprised to see the hook broken. I was expecting something else entirely