How to Replace a Balance Staff, Part 2: Removing the Hairspring and Roller

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To replace a balance staff, we have to take apart the balance assembly. For essentially all watches, we’ll end up with 4 units:

  • the balance wheel (wheel and screws)
  • the balance staff
  • the hairspring unit (collet, spring, and stud)
  • the roller unit (roller table with jewel, possibly with 1 or 2 pieces)

We start by removing the hairspring, then the roller, then the balance staff. As we’ll see in later posts, we re-assemble in reverse order by inserting the staff, then the roller, then the hairspring.

Removing the Hairspring

You have a few options for removing the hairspring. One is to use levers shaped for removing collets. They look and work much like levers for removing watch hands.

A second option is to use a V-shaped collet removing tool. The vintage K&D tool in the picture is probably what I use the most.

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The curved end is slipped under the hairspring. The sharp edges in the slot, with some light twisting, will loosen the collet. This tool comes in a couple sizes.

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A third option is to “twist up” the collet. (Fried describes this method in The Watch Repairer’s Manual.) You stick a flattened pin or oiler into the collet’s slot, twist slightly to open the gap and loosen the collet, and then twist, pulling up. This will loosen it, and the effect is like “unscrewing” the collet from the staff.

In all cases, our main worry is deforming the hairspring. Easy does it. Don’t let the tool slip, and avoid bending the spring at the point where it is pinned to the collet.

Removing the Roller

Then we remove the roller from the staff. Again, we have a lot of options.

First, if you have a vintage Platax tool (shown in this post by Christian at The Watch Guy), by all means use it. But you probably don’t.

A second option is a handheld roller removing tool. These are inexpensive and popular.

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To use this tool, the sharp jaws of the tool are placed between the roller and the staff. With a light squeeze on the ends, the roller should detach from the staff.

I’m not a fan of this thing, I must say. I don’t feel like this tool affords precise control, and around half the time it either doesn’t work at all or loosens but doesn’t remove the roller.

The third option is my favorite: the staking set. I prefer it for many reasons:

  • it is precise and well-controlled
  • watchmakers have been removing rollers with staking sets for well over a century, so buying single-use tools is unnecessary
  • I’ll need the staking set for removing and replacing the staff anyway, so I might as well break it out now
  • just as some people irrationally want to buy everything they own at Costco, I need no excuse to open up the staking set
  • my son likes to help with the staking set, and that fellow can wield a brass hammer better than most little kids.

Stumps for Removing Rollers

If you’re new to staking sets, the best book by far is The Watchmakers’ Staking Tool, by George Lucchina and Archie Perkins. The first section, written by Lucchina, briefly describes the history and evolution of staking sets. The second section, written by Perkins, gives a long overview of what the parts are and how to use them for common watchmaking tasks. Archie Perkins is one of the great writers about watch restoration, and this section is fantastic.

Perkins recommends two stumps for removing rollers. For this stump, the roller is placed facing up, and the roller table rests on the stump.

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This stump is similar, but notice the cut-out slot to accommodate the roller jewel. In many older pocket watches, the roller jewel extends from both sides of the table and would be snapped off if you used the V-slot stump.

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Here’s what it looks like in action.

Your staking set ought to have a few of these stumps, so we must measure for the best fit. If the stump is too small, the balance wheel won’t fit. But if it is too wide, the roller table is supported only by its edges, so it might bend or snap when you punch out the wheel.

With a staking punch, the balance staff is tapped downward, detaching the staff and wheel from the roller table. Perkins recommends these staking punches for tapping out a balance staff:

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They have a recessed tip to accommodate the pivot and a clean-out hole if things go awry.

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Your staking set should have this punch in several sizes, so again we measure. Your balance staff is broken, but we want to pick a punch with a close fit so that the pressure on the staff is even and consistent. Try a few until to find one that fits over the pivot without binding on the staff.

With your staking hammer, lightly tap the punch until the roller detaches from the staff.

The Next Steps

If all went well, you have a hairspring, a roller with its jewel, and a balance wheel with a broken staff still in it.

In our next posts, we’ll learn how to remove the old staff and insert the new one. The process is different for friction-fit balance staffs and riveted staffs, which get their own posts.