Could anybody work on a screw this small?

[Bill2024]

I was in London recently and took the chance to visit the Clockmakers Museum which is now hosted at the Science Museum. It’s free and well worth a visit if you are in that neck of the woods. 

One of the exhibits was this screw made by Waltham. The blurb says you can fit 47,000 of them in a thimble

I assume it was used in a watch and they didn’t just make it because they could. It made me wonder though, how on earth anyone could work on something that small.

You can “see” it in the centre of the box in the picture; although you can’t really tell what it is. For all I know they cut a grain of sand in a half and put that in the box!
 

[nickelsilver]

The tiniest screws are usually ones used to hold down cap jewels or Geneva stud holders in small high end calibers. 0.30mm threads are sometimes seen here. Smaller than that I've only seen on really small balance screws. I've made 0.25mm thread balance screws; that required making an adjustable die with a 0.30 tap. I asked my tap supplier if they had a 0.25 tap as they didn't list one, and they said yes, then called back to say they do but they are reserved for one specific customer. I think that customer must be Nivarox. Luckily 0.30 and 0.25 have the same thread pitch.

 

Waltham made some amazing automatic cam operated lathes already back in the late 1800s, really the first of their type and the origin of the term "screw machine" which became what all cam operated lathes were called- up until the Swiss innovated with lathes where the workpiece itself moved, sliding in the headstock collet. These are called a- wait for it- Swiss Lathe.

 

Die is 8mm diameter like the old standard dies (which are no longer made, at least good ones).

Edited 7 hours ago by nickelsilver

[mikepilk]

Have a look at this video, from about 8min 

 

[Bill2024]

2 hours ago, mikepilk said:

Have a look at this video, from about 8min 

 

That’s a great video - thanks for posting it. 

2 hours ago, nickelsilver said:

 

The tiniest screws are usually ones used to hold down cap jewels or Geneva stud holders in small high end calibers.

 

Sometimes to look forward too when I start looking at the ladies watch movements I guess. Although it’ll be a while before I get my hands on anything high-end I suspect. 

[mbwatch]

This 1896 book details a lot of the machinery Waltham had developed before 1900 https://archive.org/details/evolutionofautom00mars_0/mode/2up

Edited 4 hours ago by mbwatch
better link

[rehajm]

Yah, the Charles River Museum has a few of those old Waltham factory machines including a screw machine or two they fire up from time to time, though I've never seen it run. I think the American Precision Museum in Vermont has one too....