French Portico pendulum problems

KBwindup

NAWCC Member
Hi all

I am currently working on the a/ m clock. The pendulum that came with it is the typical starburst pendulum bob and rod associated with portico clocks but it is wrong. The Bob need s to be almost within the brass housing and well up out of view from below the clock dial which is obviously incorrect.

The length in French inches, as marked on the movement, is equal to 151.1 mm which would put the pendulum well in view below the dial as you would expect.

I am currently experimenting with a lighter temporary pendulum but it s still loosing a LOT of time.

Any suggestions on where to go with this ??

Eamonn

20220521_104948.jpg 20220521_104930.jpg 20220504_110510.jpg 20220504_110806.jpg
 

wow

NAWCC Member
Jun 24, 2008
6,313
915
113
77
Pineville, La. (central La.)
Country
Region
Are you sure the pallets are not skipping teeth on the escape wheel? Do you get a wide swing on the pendulum? I do not see anything on the movement showing the drop of the pendulum. The only other thing I can think of is that the escape wheel has been changed.
 
  • Like
Reactions: KBwindup

Uhralt

NAWCC Member
Sep 4, 2008
5,501
804
113
Country
Region
Maybe the friction cannon of the minute hand is too loose, so that there is slippage that causes the clock to lose time? Another thing is that the original pendulum might have been a mercury pendulum. The center of gravity of a mercury pendulum is rather high, so rods need to be longer which would make the pendulum more visible.

Uhralt
 
  • Like
Reactions: KBwindup

Uhralt

NAWCC Member
Sep 4, 2008
5,501
804
113
Country
Region
A pendulum like this has also a rather high center of gravity and might work:

1653139756347.png
 

Dave T

NAWCC Member
Dec 8, 2011
4,096
337
83
NC
Country
Region
I just worked on a very similar clock, and had to replace the suspension. I had a Hermle suspension that seems to be working very well, and here's a short video that might help. This clock runs well and will run at least two weeks on a single wind. But I don't know what it's rated at.
 
  • Like
Reactions: KBwindup

Uhralt

NAWCC Member
Sep 4, 2008
5,501
804
113
Country
Region
I just worked on a very similar clock, and had to replace the suspension. I had a Hermle suspension that seems to be working very well, and here's a short video that might help. This clock runs well and will run at least two weeks on a single wind. But I don't know what it's rated at.
These movements are 8-day movements but most of them rum for more than two weeks when in good shape. Usually they start losing time a bit during the second week.

Uhralt
 

Dave T

NAWCC Member
Dec 8, 2011
4,096
337
83
NC
Country
Region
These movements are 8-day movements but most of them rum for more than two weeks when in good shape. Usually they start losing time a bit during the second week.

Uhralt
Thank you, that's good to know. Just checked mine and I'm pretty certain I wound it on May 8, and the time is perfect. Can't believe it. Best time keeper I've got!
 

Uhralt

NAWCC Member
Sep 4, 2008
5,501
804
113
Country
Region
Thank you, that's good to know. Just checked mine and I'm pretty certain I wound it on May 8, and the time is perfect. Can't believe it. Best time keeper I've got!
The clocks that lose time during the second week mostly have recoil escapements. If yours has a deadbeat escapement, it may not lose significantly time until it stops. I have two crystal regulators, one with a recoil anchor escapement and one with a Brocot escapement, which is a dead beat. The Brocot one keeps time until about a day before it stops. The other one starts losing around day 10 after winding. At the end of two weeks it may be two or three minutes late. I wind both clocks weekly, that's easier to remember than a 14-day cycle.

Uhralt
 
  • Like
Reactions: Dave T

Dave T

NAWCC Member
Dec 8, 2011
4,096
337
83
NC
Country
Region
I agree on the winding. I just want to see how long this one will run before it stops. It is a deadbeat.
 

KBwindup

NAWCC Member
I just worked on a very similar clock, and had to replace the suspension. I had a Hermle suspension that seems to be working very well, and here's a short video that might help. This clock runs well and will run at least two weeks on a single wind. But I don't know what it's rated at.
You are rhe second person to suggest that type pendulum, that might be a sign.
Thanks for that.
Eamonn
 

KBwindup

NAWCC Member
I just worked on a very similar clock, and had to replace the suspension. I had a Hermle suspension that seems to be working very well, and here's a short video that might help. This clock runs well and will run at least two weeks on a single wind. But I don't know what it's rated at.
Thanks for that
 

KBwindup

NAWCC Member
Are you sure the pallets are not skipping teeth on the escape wheel? Do you get a wide swing on the pendulum? I do not see anything on the movement showing the drop of the pendulum. The only other thing I can think of is that the escape wheel has been changed.
Hi
The length of the original pendulum is marked at the bottom of the back plate in French inches.
The escape pallets are working fine, don't know about the escape wheel, they did well if they found a replacement,
 

Forum statistics

Threads
174,396
Messages
1,523,873
Members
52,192
Latest member
danarog
Encyclopedia Pages
1,063
Total wiki contributions
2,971
Last page
Hard Life for Wristwatches by Roy Gardner