Tid-Bit 13 - Mechanism Assembly Tips
Not long ago I was reading an excellent article on moving pivots when assembling a mechanism (Some Thoughts on Pivot Locator Hooks, Scotty Dean, 4/2010 NAWCC Bulletin Article, pg 186). Scotty Dean presented a number of examples of hooks and pushers that can be used to move pivots around when trying to get them to slip into their appropriate holes. His article reminded me of several phone calls from novice clock restorers who were working on their first Vienna Regulator mechanism, and having problems getting pivots to cooperate. The one that really stands out was from a gentleman who had replaced the weight line on a years-duration weight-driven Viennese mechanism, and who couldn’t get it to run after he had put it back together. The challenges he faced are the subject of this Tidbit.
It doesn’t take much pressure to inadvertently bend, or even remove a pivot when dealing with the finer pivots in Viennese or French movements. And, while I have seen time and again that an experienced craftsman can do phenomenal work with tools that only serve to expose a mere mortal’s lack of skill, the gentleman mentioned above epitomized the problems inappropriate tools can cause for beginners. While I like to think the tips I offer in this Tidbit for putting together mechanisms can be of value to both novice and experienced clock restorers – my real focus is on those who have not yet mastered the exquisitely fine touch that renders seemingly impossible challenges easy.
Back to my friend with the weight-driven year runner that wouldn’t do its thing. Fortunately he lived fairly close, so the next weekend saw him and his mechanism at one of my benches. Whilst he only bent 2 pivots using a pusher like the top one in Figure 1, well, that is still two too many. We discussed his procedure for assembling the mechanism while straightening the bent pivots – and from this discussion I learned that he had used a pivot locator identical to the top one in Figure 1.
Figure 1 – Pivot Locators
He also mentioned how difficult it was to get the front plate of the mechanism to slip onto the posts that held it to the back plate. Especially when trying to get all the pivots in their holes. And he commented that he really didn’t have any idea how he should approach a more complicated mechanism – say a 3 weight.
So – three challenges – how to locate pivots, how to cope with plates that don’t want to slide back onto the pillars that hold them in place, and how to approach more complex mechanisms.
Let’s start with the tools I use to locate pivots as I put mechanisms back together. At one point, after bending a pivot in a Vienna Regulator, I decided to make a pivot locator that would be a bit more forgiving. It is the second tool from the top in Figure 1. It consists of a very fine pin-vise with a piece of 0.010” (0.25 mm) pivot wire that is shaped so it can be used to push and pull pivots.
I still use this tool on clocks with robust pivots – say 0.025” or larger, but have found that I bend a lot fewer pivots if I use either my bench tweezers (the larger ones labeled AA) or, on more delicate mechanisms, the very fine pair of tweezers to the bottom of Figure 1 – a pair of number 5 tweezers appropriate for handling watch hair-springs.
Even a 0.010” piece of pivot wire with a hook on the end, or a pair of larger tweezers give me too much purchase when attempting to manipulate arbors and pivots in a delicate mechanism. This could lead to a simplistic rule – use the smallest/finest tool you can for really delicate work to keep you from exerting too much force. Sort of like using the right size screw driver for the screw you are working with.
But, even with the finest tool, you will still have problems putting a mechanism together if the pillars do not want to slide into the plates.
Many of the mechanisms I work on have the front plate held in place by tapered pins set through the posts that hold the plates apart, as shown in Figure 2
