The ‘Watch-ima-collet’: The Time-Ticking History of The Collet

And because engineering is in our blood, let's look (very quickly) at how they work.

It’s all in the hinge

A single-cut collet flexes at the bottom of the cut and only grips at the very top. A double-cut collet, however, grips throughout, effectively double hinging and closing more ‘parallel-y’. Blondihacks explains it all very well below.

Obviously, the more contact the collet has with the work/tool piece, the better the stability - and the more favourable the tool wear (thanks to reduced run-out).

But collets haven’t always looked (or worked) like this. In fact, when they were first used they looked very different indeed…

ER Collet Variations  

Turning back the clock

The origins of the collet seem to point towards watchmaking between the late 18th and early 19th Century. This was a time when industrial machinery and precision engineering were gaining importance not just for the economy... but also for our wrists/pockets.

Early forms of collets were said to be simple, tapered sleeves (vs cut/hinged ones) that were designed to hold tiny, cylindrical workpieces - i.e. the mechanisms inside a watch - in place.

But to better understand the collet developments to come, we need to first look at the machines they were used on: the lathe. So, it’s time to head back to the bustling village of Fleurier and witness the path that leads to the collets we know and use today. 

Never lat(h)e, always on time: the early developments of the lathe

Independent of the bigger, industrial lathes, there were two early types of lathes that focused more on precision work: the “Swiss Universal” and “English Mandrel”. They evolved to benefit watchmakers. In fact, it was the watchmaker, G. Ve Vauscher who seemingly invented the Swiss Universal in the 1700s. Where? You guessed it. Fleurier.

According to Lathes UK (who have a website full with info on lathes), the Swiss Lathe was made from one piece of bronze alloy. And its developmental aims were two-fold: make the machine as compact as possible and remove the shackles of a complex rope-driven countershaft. The result? A hand-operated crank with step-up ratio, spiral form gears and a slide-rest for ease of use.

Albeit useful at the time, the Swiss Universal was still slow and unable to hold small workpieces on their outside diameter. A problem that, in time, would be overcome by an important Charles S. Moseley.

Time to introduce the collet

Of course, watchmaking wasn’t just in Fleurier. In fact, across the rest of Europe, the Atlantic Ocean, and into the USA, Charles S. Moseley invented a lathe in the mid-1800s (circa 1858) that would end up making Vauscher’s redundant. 

“Why?”, you ask. Well, Moseley’s was capable of holding collets - or split chucks as they were then known - meaning watchmakers now had a lathe that could hold a workpiece by its outside diameter. (Houston, we have lift off!)

Moseley's reputation was infamous. He used only the best materials and craftsmen to build and assemble his lathes. As a catalogue that sold his lathes describes… 

"The Headstock Spindle which receives the Chucks, the Loose Bearing which is fitted to the Spindle, and the Front and Rear Bushings in which they run are all made of  the Best Quality of High Carbon Crucible Tool Steel carefully Tempered to a High Degree of Hardness and Ground to Standard and Alignment by Special Grinding machinery, using Special Carborundum and Alundum Abrasive Wheels."

But now we have a few twists and turns... and the collet development timeline begins to get a bit fuzzy…

Collet confusion

In 1862, 4-5 years after Moseley's lathe hit the market, John Stark Sr improved on Moseley's lathe design and made miniature precision work easier by introducing a high-speed headstock. That seems clear enough, right?

Well, he also claimed to invent the split collet (or “chuck”) itself. Yep, 4-5 years after Moseley’s lathes had already accepted collets. Hmmm…

In fact, a number of sources point towards Moseley being the inventor of the “wire chuck” - a specialised tool perfect for holding small, delicate workpieces (i.e. fine wires for watch internals) without damaging them. But it's not clear when this was invented or if it was a different chuck to that in his original lathe.

As a random side note: Moseley's "wire chuck" supposedly had a maximum pass-through capacity of 0.204” (5mm) too.

Nevertheless, John Stark Sr still played an important role in watchmaking. His company, Stark, made a range of specialised machinery and tools for watchmaking and clock manufacturing. After his 1862 lathe, he then introduced the “precision bench lathe” which made even lighter work of small, precision tasks.

Lathes UK shares Stark’s precision lathe came well before others (at least in its use of materials and techniques vs other lathes of the time). In fact, it allowed threaded chucks, faceplates and other fittings to be mounted, meaning watchmakers could produce quality work like never before. It's no surprise it was popular.

So it seems Moseley and Stark both made chucks. And we can't clearly say who came first. So, despite them both doing a similar job, let's just assume they looked/did it differently.

WWhat happened next?

Well, so far, we've been buried deep inside watchmaking territory. And as we know, collets aren't just used in watchmaking today.

Webster-Whitcomb's (or 'WW' as they were widely known) development in 1888/89 seems like the collet's last steps before entering the world of heavy-duty machining.

And unlike the other watchmaking lathes of the time, this lathe had been fed double dinners. For years.

Their '50mm centre height Webster-Whitcomb' watchmaking lathe was built to last. Its spindle and bearings were made from the very finest grades of hardened, ground and lapped steel so they could run at high speeds for seemingly forever. As watchmaking lathes go, this was the bee's knees.

But more importantly, this lathe introduced another form of collet to the market: the draw-tube collet.

Draw-back, aim, fire

Now, as we move into the 20th century, the “watch internal” techniques are exploding into larger, more industrial applications. Hardinge Brothers, or Hardinge as they’re now known, played a particularly important role.

Founded in Chicago by Canadian brothers Henry and Franklin Hardinge, Hardinge Brothers made industrial-use, super precision machine tools. Some information online suggests Hardinge invented the 5C collet in 1901. And because, circa 1918, Hardinge catalogues showed “draw-back chucks” (collets with male threads that pulled the collet into a taper), this seems plausible.

And because they underwent a change of hands to a collet manufacturing business in ~1930, this could be when the draw-back collet became the infamous 5C collet. 

Patents. Patents everywhere!

After Hardinge’s collet developments, the timeline starts to get real busy, real quick.

Documented over the next 70 years are a number of patents. For example, in 1929 Van Norman Machine Tool Co. patented this process for making a collet.

Collet Patent US1735804 | Source: Google Patents

In 1932, there was a patent for a feed collet from Luers John Milton allowing material to pass through the collet and stay centred.

Feed Collet Patent US1842036 | Source: Google Patents

1944 saw the Collet Chuck patent from Allison Chuck Products, Inc., which allowed you to engage or disengage the collet chuck without stopping the spindle. 

Collet Chuck Patent US2345069 | Source: Google Patents

And there were many, many more. It’s likely that sometime between here and the 1970s, the E-collet was introduced. Where, who or how is unclear. But we do know that the infamous ER collet came as a development from the already-existing E collet. Let’s look there next. 

The ER collet

Almost like destiny, we come full circle and arrive back in Switzerland. Because it was here that the next big collet development occurred. The ER collet. Building on the less documented E collet, the ER collet, like a lot of engineering advancements, came as a solution to a problem.

The problem: if you force a collet hard enough into the tool holder, it sticks. So, to get it out, you get to use every engineer’s favourite tool... a hammer. And hit it. Hard. And whilst it’s great for relieving stress, it’s not so great for the collet. Hence why (despite using a brass rod or bit of wood) many got and still get damaged.

This problem was brought to Fritz Weber and team at Rego-Fix, and in 1972 out came the ER collet. (It looks as though this might have been the first double-cut collet too.)

Alongside the benefits of double cut vs single cut, the ER collet added an extraction groove to the outside and then a special nut with a lip inside, which made the collet easier to remove. Fritz Weber and team took the E of the existing E collet, introduced the special removal features and added the “R”. Just the “R” actually came from Rego-Fix, not removal…

Time to collet a day?

Never! Since the introduction of the ER collet, more niche developments have hit the market. Whilst the premise is the same for them all, there are now collets better suited for more specific applications or to further ‘efficienc-ise’ manufacturing processes.

Royal Products introduced a “quick change” to speed up the changeover of collets.

Some companies now offer sealed collets to protect against contaminants and debris. And there are even higher precision collets for aerospace and pharmaceutical applications, which allow for better concentricity and less run-out.

Heck, there are even some hydraulic collets, called “power collets”, that use hydraulics to hold material steady under particularly high forces.

So, whilst we started in the beautiful, bustling town of Fleurier with the Swiss Universal lathe, we now have endless types, shapes and sizes of collets that enable a whole range of machining tasks in a whole range of machining environments all around the world.

For us, it is time to collet a day. But not without giving a special thanks to Tony from Lathes UK, whose website helped fill in a lot of the blanks with this article. His site is jam-packed with detailed information regarding all things lathes. Here’s a link to his site if you’d like to read more.

I’ve done my best to be as thorough as I can with this but if you spot a mistake, please let me know. Until next time!