Seth Thomas Adamantine Clock

I repaired this Seth Thomas Adamantine clock last week. The movement is No. 89C, a popular movement for mantel clocks, using a semi-deadbeat escapement. This one needed a lot of work, including making a new dial (it had a terrible replacement dial), making a new front strike mainwheel bushing, and replacing both click rivets and clicksprings (the clicksprings were the unreliable flat steel type, one of which was broken). I routinely replace these with round spring wire springs. See the slideshow below for photos of some of the repair steps. Here are some movies of this clock in operation:

The time mainspring is 0.016 inch thick (thinner than average) yet the escapement takes a great motion!

Here is a slide show of some of the repair steps:

Job 4767.

Share this post:


One comment

  1. Very cool. My wife recently bought an early Seth Thomas adamantine clock which has got me started on learning about clocks. From what I can figure, at some point in the clocks life the original movement was replaced and it now has the 89 in it – there is a hole under the 12 on the face to regulate the older movement but another one under the dial has been added to accommodate the 89. You can also see where the case itself has been modified inside on one side to make clearance for the gears.

    Anyway, I just wanted to let you know that I really appreciate the detailed slides and video of the movement – it really helps to see the actual thing working as I’m reading through books and trying to get a better understanding.

    Thanks again,


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.