Brass bushings versus jewel bearings

[ifibrin]

Is there any reason why brass bushings were/are used in movements? Is there some marginal benefit to using brass bushings over jewel bearings for certain applications?

I understand there may be cost savings if the pivot hole is drilled directly into the plate or bridge, but the cost saving if pressing in a brass bushing over a jewel bearing must be very marginal.

[HectorLooi]

I think it's purely dollars and cents, because I can't see any advantage of using brass over rubies. But I've only seen brass jewels in pocket watches and a couple  of cheap vintage movements.

If you do come across any worn holes in the mainplates or bridges, rebushing with brass is definitely easier and cheaper than jewelling it with a ruby. I can turn a brass rod into any size bush easily, but I have about 1000 scrap jewels bought from eBay and I rarely find a suitable jewel for the one I wish to replace. And buying individual size Seitz jewels can be quite costly.

[JohnR725]

Usually they're not separate brass bushings. If you look at a lot of watches they'll have an oil sink they might look like their separate but they're not.

As far as manufacturing goes you can drill a hole for a pivot or a larger hole for a jewel. But then you still have to push the julienne or mount it somehow it's additional steps. Then even at millions of jewels purchased they still have a cost which is more than a brass bushing there's more steps involved in manufacturing and putting it on the plate.

Then I still just can't quite think of any place where seen separate brass bushings? I don't suppose you have an example photograph?

One of the disadvantages of jewels? If you are importing watches in the United States not sure where that started but ended in the mid-60s we had tariffs to protect the watch industry. That meant that any watch imported in from anywhere almost would have an additional charge or possibly additional charges. Like the number of jewels bumped up the price it's why typically watches on the backside will say unregulated because regulated bumped up the price. There were some minor exceptions to this when the watch companies there were still in business in the late 50s and 60s set up manufacturing facilities on I think the virgin islands so watches were imported their finished by the companies are brought into the US as their own and that I think aloud the watch companies to avoid the tariffs on the movements. Otherwise the consumers were screwed because we had to pay a little more money for Swiss watches or anything from out of the country.

[rodabod]

There are some cases where it starts to become impractical to fit a jewel when it is in very close proximity to the edge of a bridge or plate.

[rodabod]

I did also recently find a table for the differences in friction between steel/brass and steel/ruby, oiled/un-oiled. There isn't a huge difference.

[mikepilk]

6 hours ago, HectorLooi said:

I think it's purely dollars and cents, because I can't see any advantage of using brass over rubies. But I've only seen brass jewels in pocket watches and a couple  of cheap vintage movements.

If you do come across any worn holes in the mainplates or bridges, rebushing with brass is definitely easier and cheaper than jewelling it with a ruby. I can turn a brass rod into any size bush easily, but I have about 1000 scrap jewels bought from eBay and I rarely find a suitable jewel for the one I wish to replace. And buying individual size Seitz jewels can be quite costly.

I don't have the tools to turn brass bushes. Cousins only sell brass bushes in packs of 10, which cost twice the price of jewels (sold as packs of 3).

I too bought a selection of jewels from ebay. I have found no problem in finding replacement jewels, usually for the automatic winding mechanism where brass bushes have worn out.

 

[HectorLooi]

2 hours ago, mikepilk said:

I too bought a selection of jewels from ebay. I have found no problem in finding replacement jewels, usually for the automatic winding mechanism where brass bushes have worn out.

 

You have to be born under a lucky star. I don't get such luck.

Even when it comes to screws, I can go through 500 screws and not find a suitable replacement. I started making my own screws recently. 

That reminds me, I've got a bag of 1000 screws waiting to be sorted. 

[mikepilk]

3 hours ago, HectorLooi said:

You have to be born under a lucky star. I don't get such luck.

Even when it comes to screws, I can go through 500 screws and not find a suitable replacement. I started making my own screws recently. 

That reminds me, I've got a bag of 1000 screws waiting to be sorted. 

I sometimes have to enlarge the hole a touch.

Screws - I have the same problem, and as for the selection of stems I bought, I've never found a match !