Any use of this milling machine nowadays?

[rafau]

Hi!

I got this vintage milling machine (gearwheel cutting machine) some time ago and restored it a bit. It was rusty and totally stuck, now looks a lot better and everything works smooth

Still some cutting discs and the chest are waiting to get polished/sanded/painted.

 

 

Do you think this antique tool still come in handy in contemporary watchmaker’s workshop from time to time? I know it looks the best on the shelf under a glass cover but can still do the job if necessary

 

 

 

 

 

[jdrichard]

I could use something like this to cut gears. Where did you get it?


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[nickelsilver]

This is a rounding up tool (also known as topping tool). It will profile gear blanks that have been divided with appropriate slits or reduce and/or rectify the concentricity of existing wheels. It doesn't have the ability to divide, the cutters are designed to use the existing gear to index each toothspace.

These were used a lot 120+ years ago to adjust gearing when making watches; before the "American system" took over watches were largely individually hand fitted.

With a good set of cutters they are useful, in certain circumstances. I use mine a couple of times per year I guess.

[rafau]

Thank you for the details! I knew it’s not able to create a gear wheel from the „blank” but can be used to cut or correct the teeth in an existing gear. I appreciate your comment and explanation.
I got it as a gift from my father who was a watchmaker and still has some equipment stashed in his basement. My grandfather and his father-in-ław were watchmakers too and this tool was inherited by younger generation in my family.
Here’s how it looked like when I got it. Quite a miserable condition Almost totally stuck.

Edited July 22, 2020 by rafau

[nickelsilver]

That's awesome that it has been passed down through the family. It looks like you have the "full set"* of cutters and supports *(there's always a size you don't have...).

 

I especially like that you did a sympathetic restoration, many times tools like this will get everything pressed against a buffing wheel to make it shiny, and all the original charm (and sharp edges) disappear. If you want to clean up the cutters I would suggest electrolytic removal, there are thousands of descriptions on the net, just need a DC power source and washing soda. It will remove the rust and keep the cutting edges as intact as they can be. My first machine was a gift from my teacher in school- it was far more rusted than yours, and the few cutters with it also very rusty. I managed to get them serviceable with the above method. When I got a better machine I gifted the old one on to another watchmaking student.

 

Out of curiosity , what is the diameter of the cutters? At first glance this seems to be a standard sized machine, but at some angles it seems larger. There were some that were made for clocks- these are larger and are very rare. A standard cutter is about 23.5mm.

Edited July 23, 2020 by nickelsilver

[rafau]

I will surely try the electrolytic method of cleaning. The cutters edges seem to be in fairly good condition but removing rust from some of them will be tricky.

They are exactly 23.4mm in diameter so I believe they are ordinary cutters. And they are to be used for pocket watches only as I assume?

[nickelsilver]

21 minutes ago, rafau said:

I will surely try the electrolytic method of cleaning. The cutters edges seem to be in fairly good condition but removing rust from some of them will be tricky.

They are exactly 23.4mm in diameter so I believe they are ordinary cutters. And they are to be used for pocket watches only as I assume?

Yes that would be a normal machine then. The usual cutter sets like you have, 20 to 25 cutters, are geared (haha) more for pocket and large wristwatch sizes, just because that was mostly what was made back then. There are cutters for very small wheels, and there are cutters for round bottom teeth and flat bottom teeth, there are cutters that were made to adhere to different gearing norms, there were even simple angle cutters that are useful on chronograph wheels with triangular teeth.

 

The cutters haven't been made for some time. Carpano was a major maker but I think they went out of business mid 20th century; Fraises Guye made them (or at least had old stock) up to around 2000, they were absorbed by Selection SA about 10 years ago.

 

These cutters differ from "normal" cutters two ways: first, they have teeth on a bit less than 3/4 of the perimeter*, the rest being the blade that indexes the teeth, and second, they have an enormous number of teeth, essentially making it a circular file. A watchmaker I know who was a toolmaker at  McDonnel Douglas back in the day and has an extraordinary mechanical mind sort of reverse engineered how they were made; basically a simple pantograph. The teeth are cut with essentially a trapezoidal dental burr, with a cutter head on a kind of pivot, and controlled by a rod with a 10 or 20x model for the profile. Imagine holding a pencil 1/4 of the way from the point, and running the eraser over a gear tooth model- the point will trace the profile, smaller. He made functional mock up that seemed pretty good, but we both agreed it was still a heck of a lot of work to make a cutter- easier to remake the wheel with a normal cutter!

 

*Some cutters are simply the 3/4 or so of teeth, with the rest of the "circle" cut away. These were used with a backing plate that had the adjustable index blade.

[rafau]

Wow! Seems like you know everything about those machines. Here’s one of the cutters and the maker is the most popular as you said. I will need to figure out the sizes and numbers meaning.

 

[nickelsilver]

I saw a chart way back where someone had cross referenced Carpano numbers to modules. But- you can have several different tooth "spaces" depending on which norm is used, on the most basic level toothspace is related to pi quite simply, 1/2 pi for a factor of 1.57 which means tooth thickness and tooth space are the same. But winding and setting parts often use a different factor, 1.4something for the tooth thickness, so a much larger tooth space for the same module. Not to mention even if all the above were not an issue, you'd have to determine the module of the gear you want to modify, then hope the Carpano chart is actually accurate.

 

Much easier way is just compare the cutter to the tooth space, with a good loupe and backlight. It takes a few tries on practice gears to know when it fits, but you get the hang of it.

 

If making a new wheel, you'll do the math anyway for the tooth space, then slit with appropriate saw, then check your cutters with a micrometer and loupe to catch the "sides", and off you go. A lot of my cutters have permanent marker notes on them of cutter thickness (tooth space).

 

Of note too, these work well down to around 30 teeth, in soft metals like brass or German silver. Below that tooth count the geometry gets all messed up. Back in the day I used mine mostly for replacement hour wheels. Those are simple and forgiving enough you can actually slit them with a compass and a screwhead file if you want to, then round them up. I think the last time I used it for an actual wheel was for a basket case cylinder movement that needed a wheel; had one that was a little oversize in my magic box so mounted it to the pinion and ripped it down.

 

 

[rafau]

Almost all done. Just need to sort the cutters out to get the drawer filled up