Vintage Hamilton Watch Restoration: 1956 Accumatic "B"

If watches had a family tree, somewhere on the Hamilton trunk would be the 1956 Accumatic. It's the model that pitched in the genes that continue to dominate the models in today's Hamilton line up.

The Accumatic line was introduced in 1956 and joined the Automatic K line that was introduced a couple of years earlier. The Accumatic models utilized movement made by ETA... the same ETA that produces the movements in today's modern Hamilton line. The lineage all Accumatic A-series models in the 1960's and '70s are decedents of the original Accumatic (and it's sibling, the Accumatic II) introduced in 1956.

Really, if you wanted to be picky, the precursor to the Accumatic was the Illinois Automatic line introduced in 1954... but we don't talk about that part of the family tree very often.

I jest, of course, as the Illinois line quickly became the Hamilton Illinois line which evolved again into the the Hamilton line - and thus entered the generations of Hamilton models that utilized Swiss-made ébauches.

An ébauche is a fancy way of saying partially complete movement. Swiss (and other) ébauche makers would sell their calibers to other watch brands who would complete the movements to their final specs and desires. So most of the watch brands in the 1950s and 60's competed with each other while utilizing the same basic components under the dial. That's not too unlike today's watch industry but the source of the movements is likely to be the Far East somewhere.

Anyway - one interesting branch of the family tree are the "B" models that feature a power reserve indicator, otherwise known as a wind indicator (as in wind a watch, not a breeze). The power reserve is the amount of time a watch will run on a full wind and the power reserve indicator is a numerical scale that represents potential hours from a full wind all the way back to zero. I think it's a very interesting complication - and I'm sure a lot of other collectors do too.

Hamilton used "B" models to denote something different when an existing model was changed but continued to be produced. For example, there are B models when Hamilton switched from the 14/0 sized movements to the 12/0 movements that replaced them and created models like the Boulton B, et al. B models were also used when Hamilton switched over from Illinois-branded calibers to Hamilton-branded calibers in the 1956-57 timeframe. The watches look the same on the outside (for the most part) but the movement inside is different.

The Accumatic was made for three years, starting in 1956. It had white or black dials and dials with all numerals or with luminous markers and numerals. The case is sometimes referred to as a "flying saucer" design and reminiscent of other models produced over the same timeframe with similar lugs.

The Accumatic "B" was not cataloged so I can't say for certain if it was only produced for a short while or it was an option alongside the regular Accumatic. I know it's an Accumatic "B" because it says so inside the case.

You can check out the Accumatic II B on this post and it used an Illinois movement, maybe it was just a way to use up inventory? For example, the 1954 Signamatic B had a power reserve indicator.

My project watch arrived in a few pieces but nothing too intimidating. The power reserve indictor shows about 16 hours remaining in the barrel, but it's not running. The hour and minute hands don't watch the sword-style hands shown in the catalog but Hamilton was known to use whatever hands they had available, especially during busy seasons like Christmas or graduations. I love the red tipped second hand, that's always very fun to find.

The case back unscrews and it's clearly marked Hamilton. No surprises here.

It's a little grungy inside but the case back clearly shows that this is an Accumatic "B". I've seen Accumatic II "B" cases as well.

One of the pieces that came with the watch is a new stem, complete with it's original Hamilton envelope. That's always good to know but if you couldn't find part number 614872 you could always find the stem for the ETA caliber that the movement is based on. The movement inside the Accumatic is a Hamilton 672 but it's based on an ETA 1256.

There's a white crown inside the kit too so I have pretty much all I need to get this watch back together.

Here's an interesting find. The rotor is a generic replacement. Perhaps something happened to the original and a watchmaker way back when ordered a replacement. It reminds me of the "who's gonna know, they're gonna know" memes you'll often see. Does it really matter if the rotor / oscillating weight doesn't say Hamilton? Depends on who you ask, I suppose.

There are no case screws to hold the movement inside the case. The movement is sandwiched inside a movement ring and the movement ring is secured inside the case by the gasket and case back. I like this kind of design - it's easy to reassemble.

With the dial and hands out of the way you can start to see the business end of the wind indicator. It's a mini dial that rotates around the hour wheel. It's not driven by the hour wheel though. There are additional parts that drive the wind wheel and they connect to the mainspring barrel. Three screws secure the bridge that holds all the parts in place.

With the bridge and the wind wheel out of the picture you can start to see the complexity of the power reserve complication. The small pinion at about 9:00 is driven by the outside of the mainspring barrel on the other side of the main plate. That pinion turns the outside of assembly of wheels that drive the wind wheel. All of these parts just lift straight off.

The assembly is comprised of several wheels that are a planetary design - they all rotate around the center. This very cool design allows the inside of the assembly to rotate and increase the wind indicator when you wind the watch. While the watch runs, the outside portion of the assembly will cause the wind indicator to rotate the other direction, all the way down to zero. The little spring sticking out of the bridge prevents the wind indicator from going past 40. So you can wind and wind and wind the watch manually but the indicator will not go past 40.

I noticed a couple of interesting things once I remove the wind indicator bits. The set lever is not attached to the set lever screw. Maybe that's why there was no stem - the set lever holds the stem in place. Furthermore, the detent on the yoke is broken. This part is what you feel pop when you pull the stem into the set position or push it back in to the wind position. You can see the broken part on the right side of the yoke.

Here's a close up of the broken arm. This is not unusual and this arm eventually fails from fatigue after 60+ years.

Flipping over to the back of the movement, three screws secure the automatic framework to the movement.

One screw, in the center, secures the framework to the oscillating weight.

Just for fun, I'll wind the watch and see if it runs... it does, and not too bad but the bear error is a little high. More on that in a bit.

Stripping the parts down to the main plate and you'll notice another gear inside. This flat gear is driven by the mainspring barrel, but not the outside of the barrel that drives the center wheel. This gear is held in place by a flat head screw.

Looking at the barrel, the barrel cover has teeth around the center - that's what drives the wind indicator. The barrel also features a longer arbor that extends well through the main plate to drive the wind indicator.when the watch is wound.

While all the parts are being cleaned I dug out my stash of yokes for this caliber.

Everything is cleaned, dried and ready to be reassembled.

The partially reassembled movement is ticking away with a nice motion. Notice the TXD on the balance cock. That's the import code for the Illinois brand. So this movement is actually an Illinois movement like in my Accumatic II "B" I posted about.

The amplitude has increased and the beat error is 2.7ms. That's under my personal specs of 3.0ms so I'm going to leave it as. That's partly because this design has a fixed stud location on the balance cock and the regulator has to be manipulated to get the balance off. So there's a lot of risk of damaging the hairspring if I attempted to reduce the beat error. I've learned the hard way that it's best to let sleeping dogs lie.

With the movement running nicely, I can turn my attention to the dial-side of the main plate. I'll start with adding the new yoke and detent.

Next on are the cannon pinion, minute wheel, hour wheel, setting pinion and the wheel that drives the wind indicator.

A small set bridge covers the minute wheel and set pinion with two tiny screws that are very easy to lose if you're not careful.

The assembly of stacked wheels goes on last before I put the final bridge in place.

Home stretch... the movement is ready for the wind indicator wheel and the dial. There's a zero indicator on the bridge so I'll drop the wheel in place using the zero for alignment.

Ready for the dial and hands to go in place.

The dial is held in place with two dial foot screws. The wind indicator is at 28 but that's just because of the position I dropped it in place. Once I wind the watch fully it will increase to 40 and from there it can run it's way down to zero... hopefully.

I also received a Hamilton 672 oscillating weight to complete the restoration. That conflicts with the TXD import code but "who's gonna know?". (They're gonna know)