# CuckooCuckoo Pendulum ?

#### SgtJCJ

##### Registered User
I am new to clock repair. I was successful in the first few and it hooked me. I am building a craftsman/mission style clock for my wife for Christmas out of a movement I got at an antique show. I have the movement functioning quite well now. My question now is about pendulum length. If I have a movement that requires a pendulum of 9", where is it measured to/from? Second may be a question for some physicists. If the pendulum must be 9", is it measured to the bob's mass center, or where it connects to the rod? This could potentially be a huge difference depending on the bob's connection point. I have done a search on the bob's connection point, but the only answers I found were way above my head. Thanks all.

#### Willie X

##### Registered User
First, good luck with your new hobby.

On cuckoo pendulum measurements, they are usually listed as from the center of the leaf to the hinge point at the top.

Note, don't waste a lot of your time measuring. Just get a cuckoo pendulum stick and a leaf bob of your choice. Slide it up or down until the clock keeps time, that's it. No measuring needed.

You mention a mission case. A cuckoo movement is designed to power a very light pendulum over a wide arc. You can use a light metal pendulum but a large or heavy one probably won't work well.

Willie X

#### shutterbug

##### Moderator
Staff member
NAWCC Member
I agree in principle with Willie, but would get the longer pendulum. They are easy to shorten, but very hard to lengthen

#### SgtJCJ

##### Registered User
I understand the concept of the sliding bob. And, yes, longer is better to start with. I lost my board stretcher a long time ago. I am finding that you are completely correct in using a heavy bob. Too much drag, I think. I am just trying to give the appearance of a longer pendulum by changing the mounting point on the bob itself. If the mounting point is irrelevant, but the center of the mass that makes the pendulum length difference, I can adjust the weight of the bob having the top of it heavier than the bottom to give that appearance.

#### Scottie-TX

Deceased
You can in fact make pendulum longer by adding weight at or above center of stick. However you won't add two inches but perhaps a quarter to half inch. Too much added weight and again you'll run into power problems.

#### Willie X

##### Registered User
If you want a noticeably longer pendulum you will have to modify the escapement. I have seen modified cuckoo movements in cheap wag on wall clocks sold to the tourist trade. Pendulums are 20 to 24 inches long. Main mods are to add a suspension spring and an escape-wheel with fewer teeth.

Willie X

#### Scottie-TX

Deceased
Yupper! That's the cubic zirconium upgrade. Go 4 th' GUSTO!

#### Randy Beckett

NAWCC Member
What kind of cuckoo movement do you have?

#### shutterbug

##### Moderator
Staff member
NAWCC Member
You can in fact make pendulum longer by adding weight at or above center of stick. However you won't add two inches but perhaps a quarter to half inch. Too much added weight and again you'll run into power problems.
I think you're wrong about that, Scottie. It will cause a faster escapement, not a slower. To make that happen you need a compound pendulum - weight added above the rotation point of the pendulum.

#### Tinker Dwight

##### Registered User
Hi SBug
Scottie right, adding weight at the center of the pendulum will make it
run faster, allowing one to increase the length.
It does so by moving the sum of the moments up the rod. ( sum MR^2 ).
This is what he wants. Not a slower pendulum.
Tinker Dwight

#### SgtJCJ

##### Registered User
Randy, I have a Regula 34.
All, I have added some simple blocks of wood with a slide to the top of the pendulum. I ave been able to add 2" to the overall length of it. However, it just isn't the right way to do things and looks bad. With the size of the case I am building, it will be hidden, but, I'll know it's there.

#### Randy Beckett

NAWCC Member
I don't see why you couldn't use one of those decorative pendulums made for a quartz movement in this application. They are very light with a fixed bob, but you could make a weight that could be hidden on the backside of the rod and moved up and down for rate adjustment. I would think that the length could be increased quite a bit this way, with the rate adjuster high up on the rod, though I'm pretty sure it wouldn't be 2 inches.

Christmas present for your wife. I wouldn't tear into an escapement modification at this late date. I never modified one this way, but I doubt the parts are totally, Plug and Play.

Edit- I was typing while you posted. You may not like the looks of what you have now, but you have proved that it will work. Just make a metal (lead, steel, brass) weight of the same weight of your wood block and attach it to the backside of the rod at the same place your wood block is now. You can still use your bob for fine tuning the rate.

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#### Tinker Dwight

##### Registered User
Perhaps you should consider a different movement.
Cuckoos generally have short pendulums. Typically
more than 100 BPM.
What length pendulum do you expect to have?
Tinker Dwight

#### SgtJCJ

##### Registered User
I will not be taking on the changing of the escape wheel prior to Christmas. I will be adding a small denser weight like Randy described at first. I will be attempting the escape wheel on a second movement I have. Once complete and tested, I will swap the movements.

I am hoping for a 10+ inch pendulum, which is not unheard of. Regula makes a 34 with a 28.5cm length.

#### Randy Beckett

NAWCC Member
Sounds like a good plan. Great Christmas present. I wish I could think of something that good for my wife.

#### Tinker Dwight

##### Registered User
I will not be taking on the changing of the escape wheel prior to Christmas. I will be adding a small denser weight like Randy described at first. I will be attempting the escape wheel on a second movement I have. Once complete and tested, I will swap the movements.

I am hoping for a 10+ inch pendulum, which is not unheard of. Regula makes a 34 with a 28.5cm length.
I'll look at the 34 models I have and measure the pendulums.
You know that the verge span has to match the escapement.
You change on and the other news to match.
Tinker Dwight

#### ANTIQUECUCKOOCLOCK.ORG

##### Registered User
would love to get a peek at the clock when you get her done!

Sneak Peek

#### SgtJCJ

##### Registered User
Tinker, no I didn't know I had to change the verge as well. Where does one by the wheel/verge pair?

I may just have to buy a new movement.

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wow... nice job.

#### Tinker Dwight

##### Registered User
Tinker, no I didn't know I had to change the verge as well. Where does one by the wheel/verge pair?

I may just have to buy a new movement.
I don't know if these are available as parts. You might check with blackforestclocks ( forgot the URL but a search should
find them ).
If not you have two options. On get a donor clock movement with what you want or learn how to make your
own verge.
Tinker Dwight

#### ANTIQUECUCKOOCLOCK.ORG

##### Registered User
I do specialty restorations, but i would need the clock movement in hand. My parts collection is pretty massive. If you are up to it ill be glad to help out.. The donor clock is the way to go but with the endless variables it would be a real "hit-or-miss" for getting a right donor motor.

#### SgtJCJ

##### Registered User
Almost done. All the wood is finished. The movement is installed. I had to fabricate a longer pendulum wire to clear the bottom. Now I have to fabricate really long cuckoo bellow wires and bird perch. Should have it completed by Christmas.

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