Seth Thomas scape wheel problems

[Spidicus]

I have a Seth Thomas time-only movement on the bench that was mounted in a Ships clock case. (see picture) The movement showed evidence of less-than professional repairs. I cleaned it and polished the pivots, then rebushed it as needed. There seemed to be lots of power; however, when I got it back together it ran erratically. Closer examination of the deadbeat escapement revealed that two or three scape wheel teeth were falling on the exit lift face of the anchor, while the rest were falling on the exit lock face as they should. I'm guessing either I've got a couple short teeth, or that arbor isn't running true. Just eyeballing it, it appears that some of the teeth are a teensy bit shorter than the others. Does anyone know a fix for this? If I put the arbor in the lathe I could get all the teeth to the same length, but would the clock run after such a drastic modification? This seems like kind of an unusual movement, what with two big mainsprings driving one time train, so I wouldn't count on being able to find a replacement. Any thoughts welcome.
Phil

 

[Willie X]

Look up 'topping escape wheel teeth'.
Willie X

 

[Vernon]

You will be faced with making an adjustment to the pallets if you topped the wheel. Look for something bent first: teeth, pivot or arbor.

Vernon

 

[shutterbug]

Also read up on how to balance the power between the two main wheels. They can work against each other otherwise.

 

[wow]

If you will remove the escape wheel and show us a close up photo of it, we can advise you much better.

 

[Uhralt]

I agree with what the others said.
This seems to be a ST #10 movement. It is not rare and comes up on ebay quite frequently. If everything else fails, a replacement could probably be found.

Uhralt

 

[Spidicus]

Update: I put the escape wheel in the lathe and turned it by hand against a reference, and indeed two of the teeth were a bit lower. Using the technique from LaBounty's article on massaging escape wheels, I was able to draw the two offending teeth out far enough to get things ticking properly again. Thanks to all for their comments!

 

[Spidicus]

The offending 'scape wheel...

 

[wow]

Yep. Several teeth are short. You could try to salvage it by turning and cutting the longer ones down but, as was already mentioned, the pallets would probably have to be altered too. Uhralt’s idea may be best. Search for another movement.

 

[Willie X]

You need to be cautious when spreading or planishing a tooth (or teeth).

I had an S-T (89) escape-wheel tooth that crumbled when I tried to spread it a bit, earlier this year. Never had one do that before. Had to replace the tooth.

Willie X

 

[Spidicus]

Yes, begins to look like a new wheel is needed. Turns out, after a couple hours running on the bench it began behaving erratically again. With multiple short teeth present, it's possible that someone may have already tried to top this wheel. Unfortunately the anchor is a solid piece, so no bending, and I lack the skill to rework the pallets. The darn deadbeat is so fussy, and the tolerances so small, that I can hardly see the problems without the 'scope. Thanks again for your help.

 

[Dick Feldman]

A new escape wheel may not solve your problems. You said:

There seemed to be lots of power;

A movement lacking power will have the effect of the escapement not operating properly.
Have you tried to push the time train wheels by hand, noting the locks and drops?
A fair way to tell if an escape wheel is off is to press 4-6 teeth into modeling clay, making an impression with the side of the wheel. Then rotate the wheel to see if the impression matches the next set of teeth.
All too often, an erratic operating clock is blamed on springs or on the escapement when the real problem is lack of power in the train. If you have any lateral play in either the escape wheel or the verge pivot holes, those arbors wandering will seem like a bad verge or bad escape wheel. The amount of allowable side play in the pivot holes for the verge and escape wheel should be zero.
Fairly serious escape wheel problems can be solved by drawing out teeth, comparing the profile and topping the teeth using the clock train as a source of power. Are you positive you had the arbor centered when you used your lathe to check teeth? Did you use a dial indicator on the arbor near the wheel to make sure it was running true?
If you seem to be having a problem with short escape wheel teeth, it should always be the same teeth. Have you marked the teeth to be assured the problem is always with the same teeth? Generally, escape wheel teeth are damaged by someone forcing the escape wheel or verge. Short escape wheel teeth due to wear is very unlikely.
If an escapement is out of adjustment, it is many times due to someone experimenting without proper knowledge or skills. If you have a low power situation as well as an escapement out of whack, there are two or more things wrong with the clock. Two problems are more than twice as hard to trouble shoot than one. Solving one problem or the wrong problem may not make the clock movement run reliably.
JMHO
Dick