Rating pendulum

[Bob Reichel]

Have a 1785 Vulliamy movement (beautiful) and having problem speeding up the rate. The pendulum rod is rectangular and is bottomed out inside the very heavy brass, lead filled bob. I am loathe to cut away some of the rod to gain speed. Do I have any alternates? Heavier suspension spring? All the parts, rating nut, suspension spring, etc. look original. The crutch foot is in the middle of the pendulum rod slot (vertically). I have already shortened the suspension spring, as there were two holes in the top of the rod. It came to me using the longer hole and I've moved to the lower hole with no real affect.

[Bob Reichel]

Have a 1785 Vulliamy movement (beautiful) and having problem speeding up the rate. The pendulum rod is rectangular and is bottomed out inside the very heavy brass, lead filled bob. I am loathe to cut away some of the rod to gain speed. Do I have any alternates? Heavier suspension spring? All the parts, rating nut, suspension spring, etc. look original. The crutch foot is in the middle of the pendulum rod slot (vertically). I have already shortened the suspension spring, as there were two holes in the top of the rod. It came to me using the longer hole and I've moved to the lower hole with no real affect.

[Bob Reichel]

The clock movement has not run for 35 years. The case was destroyed in a Xmas stocking accident--then the restorer and the broken case both disappeared.
We are in the process of contemplating the remake of the case from old pictures. Want to assure the pendulum length in order to provide the right space inside the case.
The case is a fairly plain dark wood case with fish scale fretwork side panels.
Yes the dial, the plates and the number on the pendulum bob are all the same (1291). So you can see where I'm coming from. According to my Mumford beat setter, we are varying BPH between 8371 & 7795 (mostly around 7789 & 7855.
Can't give you picts at the moment as Canon has my piece of junk again!

[Scottie-TX]

How slow is your clock running? What quantity over what period of time?

[Eckmill]

Like Scotty asks, what kind of rate change are you looking for? Certainly a tougher suspension spring will have a speeding-up effect but not a desirable fix for a fine clock.

I'm not familiar with clocks by Vulliamy except his famed design for a dead-beat escapement, a shorter arc of pendulum motion will have a slight effect on the rate in the direction you seek due to the time the escapement is locked on the dead faces. Excessive force from too much driving weight could do that.

[shutterbug]

You may just have a dirty movement. That could certainly slow things down. Is it possible to put more threads on the rod with a die? That would be an easy fix without defacing the clock.

[Bob Reichel]

Fella's, I have to admit something. After I had made that shortening of the pendulum by shortening the suspension spring----I only thought I hadn't made a difference and became concerned that a change in the strength of the suspension spring was necessary.
The rating now is very close and I do have some adjustment left and will continue to adjust until it is correct.
Sorry, if I cried "Wolf", when I should have checked closer.

[Scottie-TX]

SHOOT! We LOVE "wolf". Yell it as often as you like. You make it easy for us: You fix your clock before we know what's wrong with it . Yeah. We can do "WOLF"!