Riveting...

 

In our last episode your local horologist solved the mystery of the dangling mainspring in the Sessions Ramona clock. 

The broken click on the mainspring wheel was a mess and researching confirmed... it needed to be replaced. 

Let's review what we had in hand.

The click was damaged. Its spring was broken. The spring hook was fine. The ratchet wheel was fine. 

Hard to note in the picture above but the tip of that click was bent and it rode very loosely on its pivot, making it highly vulnerable to slipping.

Turns out there are replacement clicks to be found from clock suppliers like Timesavers but this collector of clock bits had a couple spare clicks on hand that came from a box of clock supplies sold at a local estate sale.

But to put a new click on, the old one must come off. And that means removing the rivet it rides on.

A consultation with Dr. Johnson of JohnsonArts and it was removed as seen in our opening photo above.

Once removed what remained was a large rivet hole in the spoke of the wheel. 

The replacement click looked promising. 

But the new click rivet was different than the one that was removed. That hole in the spoke from the old rivet was far too big for the new rivet.

Here's the new click and its rivet. Note the steel spring. Should be much more robust than the brass original. As will be seen later the spring is long enough to reach the existing click hook on the other wheel spoke.

The way click rivets work is that the click itself rides the rivet's "shoulder" while the end of the rivet is hammered tightly closed into the hole in the wheel shoulder.

And how it's all meant to come together when riveted to the wheel spoke.

Courtesy of Bob Croswell, NAWCC

But the hole in the spoke is too large. What to do?

Once again the gang at the NAWCC had the answer. Just put the click on a different spoke of the wheel. Drill a new hole. The click spring is long enough to still work the spring hook.

YLH started the hole with a hand drill.

But then realized that there was a better tool for this that had been acquired on the cheap a while back.

This outer space looking gizmo is a bushing tool. 

In short, it holds a metal plate (or wheel) in place and allows extremely precise cutting. The metal is supported by a stump and positioned with the clamps. 

A great tool for all kinds of horological metallurgy.

Here's the new click and the rivet set on an anvil ready for peening in our new hole on the spoke of the mainspring wheel.

When manually riveting you peen on that end of the rivet that is sticking upwards in the photo above. Refer back to the drawing above.

When testing the fit in the new hole, YLH used a bit of old mainspring to act as a shim to ensure there was a small gap between click and the wheel spoke, otherwise the click would be too snug against the spoke and wouldn't pivot. 

We don't want it tight up against the spoke nor very loosely fit. Just enough to have gentle play and no more.

Oh a hammering we shall go...

As recommended, many pauses were had to test the rivet and how snug the click was against the spoke. 

Came out great.

And flipping it over.

As noted the click spring easily reached the original spring hook and was gently bent to keep enough pressure on that click but not so much so as to require heavy torque to turn the winding arbor. Simple to adjust as needed. 

This clock cleaner gave the mainspring a nice going over and then reconnected it to the mainspring wheel. Then wound the mainspring in the winder and clamped it with a steel C clamp, ready to go into the movement.

Whenever removed or reinstalled a mainspring is wound up and constrained by a C clamp. That clamp is very strong.

Some cleaning and reassembly of the movement followed.

Here's the reassembled movement with the click parts peeking out.

Once the movement is fully reassembled the C clamp is removed as the click mechanism can now hold the mainspring wound in place. 

The movement was reinstalled in the case. It is flipped around from the image above as the winding arbor and center (hands) arbors must go through the front of the case.

Therefore when installed the mainspring wheel sits on the inward side of the mainspring so you can't see much of the click mechanism. The mainspring is hiding most of it but in the photo below there's a tiny bit of the click spring peeking out the back.

The remainder of the clock was in excellent condition. Really nothing needed for the case, door brass, hands, the pendulum, and the dial numbers.

Speaking of the dial, one of the features that YLH very much likes about the Ramona... there is no separate dial (face). It's all one piece of oak continuing along the entire front of the clock.

Nice.

She's running strongly in YLH's living room.