261 Series

Removing a clock mainspring barrel

Removing a barrel and spring

Most often the barrel with the mainspring inside of it can be removed from the clock without disassembly of the clock movements outer plates.

This can be done with a mainspring let down tool, a device that allows you to hold the tension of the mainspring with your fist rather than your precious and fragile fingers. The idea is to put the mainspring let down tool over the square post that the key is to go onto, and then move the "click" out of the way with a flat screwdriver, and slowly allow the mainspring to unwind in your fist as you control the speed of the unwind easily with your whole fist rather then the fingers with a key.

To try this with a key usually ends up being a painful experience on the fingers. You will see the click that with its tension spring that your supposed to hold back, this click is what holds the mainspring to wind in only one direction.

Of course if the mainspring is broken, there usually is no worry as there is not much tension on the mainspring to begin with, but just to be safe on the movement, its best to be sure is in the totally unwound position.

Hole End Mainspring replacement service

Hole End Mainspring replacement service

We can do the task of measuring and installing the mainspring if you choose to send it in.

If going with the mainspring replacement because the clock is still in good shape or out of production new, then if you choose to send the entire barrel with the mainspring in it, we can swap it out for $50.

We will take out the mainspring and measure the width / thickness and approximate length and then install the correct spring back into the barrel.

If doing this please send to Clockworks PO Box 339 Huntington MA 01050 with your contact information.

It may be best also to send us an email to [email protected] so we can look out for the package.

It will end up being the $50 charge, and then add the price of the mainspring as stated in the below chart, and then shipping back to you.

If you would like to send in your barrel with the broken mainspring, please fill out the form at this link so we know its coming into us.

Assessment of damage

Assessment of damage

When a hole end mainspring breaks in the barrel the impact may have caused damage in the rest of the gear train.

It is possible that the pivots that go into the outer plates have bent or the arbors bent some, its best check on this before finding a mainspring.

The length, width, and thickness would need to be measured and then you would match it up on the chart below.

Now if the mainspring has any size at all to it, it would require special tools to reinstall the hole end mainspring into the barrel.

These tools are over a hundred dollars, if the mainspring is larger then it would be very hard to put in and dangerous at the same time.

If the movement is 25-30 years old, it has lived its life anyway. A new movement would be less trouble, cheaper than a over haul, and would last another 30 years, and easier than the repair process.

If you would like to explore the new movement option rather than replacing the mainspring, Please provide the movement numbers off of the back plate of the movement itself and email this information to [email protected] There is another option also, just send us the clock mainspring barrel and we will swap it out with the correct new mainspring for a fee.

Measuring the Hole End Mainspring

Measuring the Hole End Mainspring

A Hole end mainspring is use when the mainspring is contained in a brass barrel.

What is being measured below is the sizes of the new mainspring to match up to the old one.

The width is measured first and matched up to the width below, then the thickness is measured with a micrometer, then the approximate length.

Match the width first, you can then see what spring is closest in thickness and length that will be closest to the old one.

The diameter column is what the spring will fit best, in the inside diameter of the brass barrel. WARNING: Wear safety glasses and gloves if working with a hole end mainsprings, they can and will be dangerous. If you choose, we have a mainspring replacement service, all you have to do is send us the entire barrel.

Hole End Clock Mainspring

Clock Pendulum Style Description

Metal Lyre

This is on the left side on the picture. This is a polished brass style grid metal lyre pendulum for 85cm and shorter movement lengths. The longer lengths usually look like the other picture with the twisted rods.

Brass Rod

The brass rod has the top mounting hook and also the threaded bottom with its nut to regulate the timing. The bob with it chosen diameter will go onto the bottom threaded rod and the rating nut under it.

Wood Stick

The wood stick will come unstained. This is so the stick can be stained the proper color to match the clock case. The wood stick pendulum consists of the stick with the hardware and also the bob in the diameter chosen. The good thing about wood stick pendulums is they can be shortened if needed.

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