Clock not running slow enough.

[Bod]

I have an "Anvil" brand mantle clock, made by the London clock company in Perivale. (1930-35)
It will run reliably, but only at a speed of gaining 5 mins per day.
Lengthening the pendulum enough to reduce the 5 mins, slows the clock to a standstill. Raising the weight, restores the running and the gain.
Do I raise or lower the escape pallets to strengthen the pendulum impulse?
The works have been dismantled, old solid oil removed, no re-bushing required on the going train.

Bod

 

[heronviewer]

A very small adjustment to the pendulum length could be what you need - sounds as though you are making too big an adjustment .

 

[Roxie]

Is the clock level? If the "tick & tock" are not the same then this could cause problems as the pendulum will swing further one way than the other. Agree with Robert a little adjustment at a time (sorry no pun meant!!).
John

 

[finneyb]

No knowledge of clocks but from what has been said small adjustments could be made by adjusting the level of the clock - ie disregard whether it's level or not just adjust the level with a couple of wedges and see where it takes you. Might be more sensitive than adjusting the pendulum.
Brian

 

[CHJ]

Was the mainspring checked for cleanliness and suitably re-lubricated.
If not this may be a reason for it not supplying enough driving power to the escapement.

If this was not done then it's a job for someone who knows how to handle the spring and release the spring tension, a potentially dangerous procedure, and can damage the spring as well as the operator if not done in a suitably controlled way.

 

[Bod]

I've been lowering the pendulum a quarter of a turn on the nut at a time. Same result on 3 attempts.
The clock is in beat, but that's a fine adjustment from out to in!
The works are at present screwed to a block of wood, held in a vice, so everything is very firmly held.
The spring has been exposed, and lubricated, but not removed, because of the spring strength.
When it's stopped, it requires very very little touch on one of the gears to start the ticking, which soon stops.
Could the pendulum weight be too heavy?
I believe the pendulum is original, it fits properly. Just doesn't seem to get enough power at slow speed.

Bod

 

[NickN]

Would actually be worth trying, and easy to do, INCREASING the pendulum weight so that it has more momentum after each impulse - and if this has the opposite effect, makes it stop even quicker, then you have also answered the question of 'is the pendulum too heavy?'.

The easy way: simply stick increasingly large blobs of blu-tac on it, see what happens.

I own a few mechanical clocks of various ages and just occasionally you do get one that just doesn't want to keep time, whatever adjustments are made, though!

 

[DTR]

It will run reliably, but only at a speed of gaining 5 mins per day.

Would it be possible to have this clock installed in my office at work please? Thanks.

 

[Bod]

UPDATE
This is now running nicely, keeps good time for 4 days then loses slightly for the next 3, before winding on the 7th.
Got it properly in beat, and kept lowering the pendulum.
Gong sounds horrible.

Now on to one that runs too slow!
400 day torsion clock, 100+ years old, been in storage for a long time, runs consistently slow.
Once the bench is clear, and the dust settled, time for a complete strip down, possibly a new main spring.

Bod