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# Thread: Using just one weight on a two weight Seth Thomas movement

1. ## Re: Using just one weight on a two weight Seth Thomas movement (By: R. Croswell)

I calculated - roughly - how low I would need to keep the single weight and it is just not a reasonable solution. So I am back to using two weights. I like the idea of a bead or decorative item attached to the strings to stop the weights on the underside of the seat board. Some delicate glass cutting and drilling and it should start going together.

Originally Posted by R. Croswell
Or simply attach (crimp on) some sort of brass sleeve or little ball that would contact the seat board when that spool is full. You may have issues with driving force when the weights are at the top and angle between the cables is large. If the cables were directed over pulleys under the seat board such that they were parallel you will have more constant power over the run cycle that will be a greater advantage than any thing gained from not having the friction of the pulleys.

RC

2. ## Re: Using just one weight on a two weight Seth Thomas movement (By: THTanner)

Just my opinion and remember I'm not at all good with figures or changing of a clock movement but looking at drawing won't work using a single pulley at the bottom since both trains will cause the cable to be pulled from different sides thus not allowing it to move. I don't have any program to draw up something but why not have a pulley for each side next to each other in the middle just below the seatboard. You can have hangers coming straight down from the seatboard so no issue of the pendulum hitting. So if you can picture this you'd have the cable from the left and right both going to the middle and running over the top of those pulleys and then straight down where they'd meet the weight. You'd gain a bit of overall length needed for an 8 day wind since the cables would be going horizontal for a bit instead of going vertical the entire time.

3. ## Re: Using just one weight on a two weight Seth Thomas movement (By: Jasons34)

It actually does work pretty well, it is just cumbersome and gets in the way. The purpose of the pulley at the bottom is so that the single string can turn the pulley and keep the weight in the center as it descends when the time side unwinds and then to again remain in the middle as the strike side unwinds.

Originally Posted by Jasons34
Just my opinion and remember I'm not at all good with figures or changing of a clock movement but looking at drawing won't work using a single pulley at the bottom since both trains will cause the cable to be pulled from different sides thus not allowing it to move. I don't have any program to draw up something but why not have a pulley for each side next to each other in the middle just below the seatboard. You can have hangers coming straight down from the seatboard so no issue of the pendulum hitting. So if you can picture this you'd have the cable from the left and right both going to the middle and running over the top of those pulleys and then straight down where they'd meet the weight. You'd gain a bit of overall length needed for an 8 day wind since the cables would be going horizontal for a bit instead of going vertical the entire time.

4. ## Re: Using just one weight on a two weight Seth Thomas movement (By: THTanner)

Too bad it wasn't a chain movement. One could set it up as a Huygens instead
You not have to worry about winding because you only wind one side.
Tinker Dwight

5. ## Re: Using just one weight on a two weight Seth Thomas movement (By: THTanner)

Is the customer aware that the single weight design will place more force on the time and strike train when the weight is in the upper position, therefore wearing the movement more? Another downside is that the change in force will cause the movement to have timekeeping variations between the early and late part of the winding cycle, similar to a spring driven movement.

6. ## Re: Using just one weight on a two weight Seth Thomas movement (By: dad1891)

Originally Posted by dad1891
Is the customer aware that the single weight design will place more force on the time and strike train when the weight is in the upper position, therefore wearing the movement more? Another downside is that the change in force will cause the movement to have timekeeping variations between the early and late part of the winding cycle, similar to a spring driven movement.
This can be avoided with a fixed pulley to bring the cables closer together.
Tinker Dwight

7. ## Re: Using just one weight on a two weight Seth Thomas movement (By: dad1891)

Yes - I discussed this with them and we abandoned the single weight. And without the two pulleys per side in the usual case, I will probably be able to run it on 6 or 7 pound weights instead of the usual 8s. At this point two weights will be used and will fall pretty much straight down with perhaps a small angle to a roller near the bottom of the movement to keep the line away from the lower posts since the line will be coming off of the outside of the small drum.

Originally Posted by dad1891
Is the customer aware that the single weight design will place more force on the time and strike train when the weight is in the upper position, therefore wearing the movement more? Another downside is that the change in force will cause the movement to have timekeeping variations between the early and late part of the winding cycle, similar to a spring driven movement.
- - - Updated - - -

Nice brass chains would look better too.

Originally Posted by Tinker Dwight
Too bad it wasn't a chain movement. One could set it up as a Huygens instead
You not have to worry about winding because you only wind one side.
Tinker Dwight

8. ## Re: Using just one weight on a two weight Seth Thomas movement (By: THTanner)

Just to add my 2 cents.

You can use extra cable pulleys and cable. You can arrange pulleys so the cable is partial hidden, perhaps routed to the back unseen. Then come back around again to view.

You can double pulley a single line (pulley at top and bottom, cable wraps around twice) for example see Vienna. I think the rule is the more you pulley the system the more weight required. Don't know.

You could also strip out the strike side and make it time only. Or talk them into a two weight system.

RJ

9. ## Re: Using just one weight on a two weight Seth Thomas movement (By: RJSoftware)

Thanks RJ - I was able to talk them into a two weight system, but since it is glass and mirrors all around the cables and weights will have to be visible - but at least two weights is a lot simpler.

btw I am about to wrap up the time stamp clock - how do the pictures and drawings look?

Originally Posted by RJSoftware
Just to add my 2 cents.

You can use extra cable pulleys and cable. You can arrange pulleys so the cable is partial hidden, perhaps routed to the back unseen. Then come back around again to view.

You can double pulley a single line (pulley at top and bottom, cable wraps around twice) for example see Vienna. I think the rule is the more you pulley the system the more weight required. Don't know.

You could also strip out the strike side and make it time only. Or talk them into a two weight system.

RJ

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