Bushings for mainplate material ?

[rogart63]

I have got a Seitz tool. Thinking of boaching up some barrel arbor holes in the mainplate . And replacing the with new bushings. What material should i use. Is the ready made bushings i can buy already. Or do i have to lathe them myself. 

On the seiko 6139 the is a small bushing in some material. On the mainspring barrel bridge Think  it's  brass. Would like to be able to get a a little less wobble in the mainspring barrel. 

[jdm]

 

On the mainspring barrel bridge Think  it's  brass. Would like to be able to get a a little less wobble in the mainspring barrel. 

What about a jewel. Soft barrel bushing are a common defect for Seiko. Maybe they do that so they don't last forever and a new watch has to be purchased.

[oldhippy]

As jdm mentions I would be inclined to use a jewel.

[clockboy]

The best option is a jewel but I found the issue with a jewel is many bridge plates are too thin to take one. A while ago I did do a post where I completed this repair & I had to custom make the bushing out of brass.

[Mark]

The only problem with jewels is their expense. Plus, not always easy to obtain certain sizes for barrel arbor diameters. And finally you may find that the barrel bridge material may be too thin to support a friction jewel in certain movements.
If the wear is minimal then it may be possible, although not attractive, to use a hole closing punch then broach and smooth broach in order to open to the desired diameter, smooth broach creates a kind of hard skin on the metal.
Using bushes may not be desirable if the metal is too thin.


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[rogart63]

Jewels okay but as Mark say there are expensive and sometimes impossible to find. Even if they are the owner maybe doesn't want to pay for the extra. 

Seen Adrian at VTA doing nice barrel arbor jewels for 61/63 movement. 

But if i now would want to do a bushing what would be the best material. Bronze or brass? Bridges are often brass i think? 

[WatchMaker]

The previous forum post clockboy mentions must be...

This is a very interesting video! 

Bushings are usually made from brass btw. This being the case you could follow the great engineering approach above or you can buy modellers brass rod in all kinds of diameters relatively easily where you might strike lucky with the dimensions you need (or at least the external diameters and use straightforward drilling to refine the internal diameter you need).

I see your main aim here is to reduce play and mainspring barrel wobble. This is an interesting topic in itself and not something I've ever been conscious of in watches I've repaired. Is this a matter of professional engineering pride or is the wobble causing tangible issues in the watch you're repairing?

[Mark]

I see your main aim here is to reduce play and mainspring barrel wobble. This is an interesting topic in itself and not something I've ever been conscious of in watches I've repaired. Is this a matter of professional engineering pride or is the wobble causing tangible issues in the watch you're repairing?

It's a common enough problem. And of course, if it's not dealt with then it can get to the point where the sideshake causes the barrel to foul the centre wheel.


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[WatchMaker]

That makes perfect sense if play becomes that extreme. My watch repairing activities pale into insignificance compared to other people on the forum so I seem to have managed to escape this malady statistically so far for watches I've worked on! It's certainly something I'll keep a better eye out for from now on though. I learn so much on this forum! :-)

[clockboy]

 

 

It's a common enough problem. And of course, if it's not dealt with then it can get to the point where the sideshake causes the barrel to foul the centre wheel.


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if my memory serves me well I think that was the issue with the watch i repaired.

[StuartBaker104]

I have used seitz bushes in a mainplate and found them to be a good choice as they are slightly tapered so easy to get a good fit... although you do have to remove the excess length carefully - if you have a faceplate for your lathe this should be straight forward. They are made of "hard brass" and John Senior sells them individually by size making them quite economical. http://www.obsoletewatchandclockparts.com/Jewels-and-Bushes.htm

Recently I also bushed a mainspring barrel, but turned a custom bush from brass rod. The barrel wall was very thin and I elected to solder the bush in place.

Either way, you should plan on finishing the bush hole with a smoothing broach which will work-harden the surface.

[oldhippy]

I have been reading about this with great interest. The problems one can come across when you have too much wear at the ends of the barrel arbour. Not only can it foul the centre wheel as Mark has pointed out. It can cause any amount of wear, from the ratchet wheel teeth wearing down which can cause slipping when trying to wind, crown wheel wear which can affect all the winding wheels, the barrel bridge can suffer by being rubbed by the ratchet wheel and the barrel teeth can wear to be uneven. Jewels are the best to use that is if you can find the right one like any bush you use it is down to the right one. Bronze as you know is much harder than brass that would be my next chose. If you have the means and experience, you should be able to turn some bronze rod in your lathe to the right measurements. You might find the thickness of the plate is poor, there for the best thing to do is buy a new barrel bridge or bottom plate depending where the wear is, if not available try to find a suitable donor movement.