Help with 24 Jewel Bunn Special

[jdrichard]

I have gear 2 teeth missing on a 24 Jewel Illinois Bunn Special Pocket Watch. Not sure where to source this part. It is a small wheel attached to a larger wheel. 

[jdm]

  On 2/15/2021 at 11:04 PM, jdrichard said:

Not sure where to source this part.

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My understanding is that when is about this kind of vintage pieces one can't expect to find ready parts, and even donor movements may be hard to find, expensive, or not guaranteed to be 100% identical. So in many cases the only choice is making a new part. However for this one you might get away finding an acceptable replacement from some assortment of NOS or used parts.

  Quote

It is a small wheel attached to a larger wheel.

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That is, a pinion. It can be cut on the watchmaker's lathe with a divisor disc, milling head attachment, and gear cutter(s).

I haven't ever done that myself (but certainly want to) so I will stop talking in theory and let others give further advice. 

[JohnR725]

It would probably help if You knew what the part was called you're looking for. At the link below you can also look at the parts it looks like this is a setting wheel.

I snipped out an image from the website indicating it's a setting wheel

Then the Illinois 1923 parts book the closest you're not come to a cross reference.. So basically it's going to work in a whole bunch of 18 size Illinois pocket watches. The easiest will probably be to find a scrap movement that you can get the part from. Otherwise it's a gear cutting project as already suggested.

https://pocketwatchdatabase.com/search/result/illinois/1397944

[jdrichard]

  On 2/16/2021 at 10:33 AM, jdm said:

My understanding is that when is about this kind of vintage pieces one can't expect to find ready parts, and even donor movements may be hard to find, expensive, or not guaranteed to be 100% identical. So in many cases the only choice is making a new part. However for this one you might get away finding an acceptable replacement from some assortment of NOS or used parts.

That is, a pinion. It can be cut on the watchmaker's lathe with a divisor disc, milling head attachment, and gear cutter(s).

I haven't ever done that myself (but certainly want to) so I will stop talking in theory and let others give further advice. 

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I would really like a gear cutting system, but can never find one.

[jdrichard]

  On 2/16/2021 at 10:45 AM, JohnR725 said:

It would probably help if You knew what the part was called you're looking for. At the link below you can also look at the parts it looks like this is a setting wheel.

I snipped out an image from the website indicating it's a setting wheel

Then the Illinois 1923 parts book the closest you're not come to a cross reference.. So basically it's going to work in a whole bunch of 18 size Illinois pocket watches. The easiest will probably be to find a scrap movement that you can get the part from. Otherwise it's a gear cutting project as already suggested.

https://pocketwatchdatabase.com/search/result/illinois/1397944

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Hey thanks, appreciated.

[WellAdjusted]

Parts interchangeability is significant between Illinois 18 size models, as the image shows. Donor movements abound, and Dave's Watch Parts/Dashto has most of the specific parts you'd need for an 18s Illinois if you don't want a whole movement.

The 6th model movements were made during a period of tighter, more precise manufacturing and finishing, so one of those would be an ideal donor movement if it has the parts you need. The 2nd models go back to the 1870s and are a bit rough.

[jdm]

  On 2/16/2021 at 12:02 PM, jdrichard said:

I would really like a gear cutting system, but can never find one.

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The Chinese sell one for a reasonable price. That is the sincereclocks Ebay seller.

[JohnR725]

  On 2/16/2021 at 1:04 PM, jdm said:

The Chinese sell one for a reasonable price. That is the sincereclocks

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Is this what you're thinking about for gear cutting?

https://www.ebay.com/itm/Watchmaker-Precision-Lathe-with-Index-Plates/284180696803

What I find interesting with the above lave is it looks a lot like a vector lathe sort of

https://www.hswalsh.com/product/lathe-vector-watchmakers-48-collets-hl11

There is an example all set up to cut gears. Then while I know it's blasphemy for me to say this but even though this may possibly be the traditional way watchmakers cut gears it's a really poor way to do it. Then it's hard to tell in the pictures is there any difference in quality between the vector lathe and the other name? Even the one in this link to me I don't know looks cheaper somehow but maybe it's my imagination. I know with some other Chinese machine tools they come in various grades like in this country the harbor freight variety there made sheep some work great some don't and that may have higher-quality versions or made the better specifications hopefully they don't do it with the watchmaker's lathe as you would want to make sure you get a better quality version

https://www.ebay.com/itm/1Set-Brand-New-Watchmakers-Precision-Lathe-Assemble/124350711492

In real life even though watches are small going to a bigger lathe adds a heck of a lot of stability to what you're doing. You really want things rigid and all is belts and pulleys not the best way to do it even if all the books show that's how watchmakers cut their gears.

  On 2/16/2021 at 12:31 PM, WellAdjusted said:

Parts interchangeability is significant between Illinois 18 size models, as the image shows. Donor movements abound, and Dave's Watch Parts/Dashto has most of the specific parts you'd need for an 18s Illinois if you don't want a whole movement.

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Looks like you have your choice partial movements at the second link and part number 33 on the first link. $12 and if you scroll down the page pictures of all the movement parts.

http://daveswatchparts.com/IllinoisMaterial.html

http://daveswatchparts.com/IllinoisMovements.html

  On 2/16/2021 at 12:31 PM, WellAdjusted said:

The 6th model movements were made during a period of tighter, more precise manufacturing and finishing, so one of those would be an ideal donor movement if it has the parts you need. The 2nd models go back to the 1870s and are a bit rough.

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That's one of the unfortunate problem of American pocket watch parts. Get a nice book shows all the parts they claim the interchange and they may or may not really interchange. Look at the 12 size watches some of those were made over quite a number years and end up with all sorts of interesting variations. But this is a pretty basic parts it should work.

Edited February 16, 2021 by JohnR725

[jdm]

  On 2/16/2021 at 7:43 PM, JohnR725 said:

What I find interesting with the above lave is it looks a lot like a vector lathe sort of

https://www.hswalsh.com/product/lathe-vector-watchmakers-48-collets-hl11

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That is the Chinese watchmaker's lathe imported, rebadged, reboxed and resold for an higher price. In addition it comes with some accessories made in Europe. Boley also sells it https://boley.de/en/shop/1617.mini-lathes/685000.mini-lathe?q=Vector

To know a bit more about the history of the Chinese lathe (which has been around for since many decades one can read http://www.lathes.co.uk/chinese-watch-lathe/

I wrote the below to summarize prices and options. It's not a priority for me right now, but I probably will get one at some point. Mark also has one.

 

 

[JohnR725]

The concern I have with Chinese lathes are or anything from the Chinese is the quality? I've seen stuff they've made of very high quality and other stuff not made of high quality and sometimes it's hard to tell in you cannot always tell from the picture. Sometimes you buy something based on a review and at the time you get yours the difference is quite a bit. But there is a lot of potential there

Then I forgot up above but I'm familiar with the vector lathe. We have one that came in the box purchased secondhand from a school that went out of business. It actually is a really nice Lathe I just wouldn't recommend it for gear cutting.

for gear cutting you really want something bigger and heavier even when cutting Watch gears. It's usually assumed that cutting tiny parts requires tiny cutting tools may be the cutters are tiny but ideally the machine should be bigger and heavier.  Then it's always nice to get away from indexing plates and go to a worm gear with A stepping motor it really opens up a lot of possibilities.

[jdm]

  On 2/16/2021 at 9:22 PM, JohnR725 said:

The concern I have with Chinese lathes are or anything from the Chinese is the quality?

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Well, as mentioned Mark and other people "on the Internet" have spoken good about it. There are other bits of discussion here and there on this forum. It's not just the hobbyist that that consider price first, as other choices whatever their natura can cost easily 5 times as much.  

 

[jdm]

Here's what a well known watchmaker told me on the subject of cutting pinions. I was wondering about the work sticking out too much on order to make it reachable with the cutter wheel. 

I've only cut pinions between centers a couple of times. It is an excellent way to do it, but the setup time is usually more than it's worth. Usually you can start with a larger bar, and neck it down and maintain rigidity. For example, a 0.8mm pinion with 8 teeth. I would use perhaps a 3.5 or 4mm bar, then step it down until I had enough of the right diameter sticking out to cut the teeth. The steps will provide clearance for the cutter teeth. Smaller diameter cutters are helpful here, most of mine are 8-12mm diameter. The cutter might bite into one of the steps but it doesn't matter. So with a 10mm cutter I would have a maximum of 7 or 8 mm sticking out of the indexer typically; at 8mm I can comfortably cut 3mm worth of pinion teeth which would almost always be plenty. Then it goes back in the lathe and all the features are turned (pivots, shoulders, rivet etc). In the sketch that's a 4mm bar, with 8mm sticking out. Stepped down, cutter just kisses the steps (could bevel them if wanted but like this is fine). 3mm of pinion can be cut.