Buren 370 Disassembly

[frenchie]

Hi everyone,

 

I'm working on a buren watch right now (very nice 370 movement in there, I'll post pics later). It needs a new mainspring but I already have a replacement.

picture of the movement (not mine) : http://forums.watchuseek.com/f11/pre-hamilton-buren-cal-370-a-654132.html

 

My question is : how do you disassemble the darn thing ??? I'm especially curious about how you remove the copper colored wheel that sits on top of the bridge. I don't want to force it, I'm sure there is a trick...

 

Thank you for any help !

[bobm12]

Hi frenchie,

 

Good to talk to you again. As for the Buren, I haven't worked on those yet but in my mind I believe you need to first remove the "bar" on top...there is a screw there. Maybe it is a bigger disassembly until you get to it. I would go this way: first make sure the main spring doesn't have any more tension by "unwinding" it (by holding the click open). Then I would go for the balance wheel to avoid damaging it (just in case). Then the "bar" and finally other wheels. Of course, I'm thinking the movement will be already out of the watch.

 

In any case, take plenty of pictures!

 

Cheers,

 

Bob

[clockboy]

Best of luck with this one Frenchie.  A new one with me as well could be an interesting post to follow. 

[Geo]

You will have to remove the centre wheel stabilising bridge first as Bob says.

To remove the five spoked wheel you ideally need a "sweep wheel puller". This loos like any normal Presto type of puller, but when examined closely, you will see it has one hook on one side and two hooks on the other to allow it to grip in between the five spokes. If you do not have the proper tool, be very careful if you try to lever it off, as the extended shaft will snap way too easily.

Here's what the tool looks like. Sorry it's not the bast image as it was taken with my iPad camera.

[Marc]

The wheel in question is the centre seconds drive wheel which is a push fit on to an extended third wheel arbor which protrudes through the train bridge, and drives the centre seconds pinion.

 

As I said, it is a push fit so should simply pull off, however, the extended third wheel arbor is very delicate and if you try to lever it of from just one side you will snap it.

 

You can get "presto" style pullers for this (or modify a set of hand pullers) but in the past I have successfully used fine hand levers, working diametrically opposite sides of the hub at the same time, between the spokes. Levering at the rim runs the risk of damaging teeth, distorting the wheel, and again, breaking the arbor.

 

If you can't lever at the hub one approach is to use two thin blades (single edged razor blades are good) and slide then in between the bridge and the wheel to wedge the wheel gently upwards, however, this runs the risk of scratching the bridge.

 

Reinstallation is done with a staking set.

 

Good luck.

[Marc]

You just beat me to it Geo.

[frenchie]

You are awesome guys, thank you !!!!!!

 

Will try later tonight and see what happens :)

[StuartBaker104]

I used a pair of swiss army knives a couple of times for this job before i got hold of the correct tool. Much easier to hold than razor blades! To protect from scratches cut a v shaped slot in a piece of paper and put it under the wheel first. Have also heard of people doing this inside a plastic bag to stop the wheel going into low earth orbit.

Always anxious about the jewel on the other end when refitting these. Back in the day there was probably a special movement holder with a pin to support the pivot when refitting... Or (thinking out loud here) should I be using a small flat stake in the bottom of my staking set?

S

[frenchie]

Always anxious about the jewel on the other end when refitting these. Back in the day there was probably a special movement holder with a pin to support the pivot when refitting... Or (thinking out loud here) should I be using a small flat stake in the bottom of my staking set?

S

 

Good question, hadn't thought of that... any advice ?

[Geo]

I've done a few and haven't had any problems. If you have a staking set use that to keep the alignment, but only use firm finger pressure when pressing the wheel on with a suitable stake.

If you do not have a staking set, press the wheel on as you would a hand, but be very careful to ensure you push perfectly in line with the axis of the shaft. If not, you will either bend or break the shaft.

[frenchie]

Thanks again for all the help guys !

 

Update :

- I used the 2 razor blades in a plastic bag method, and that cool wheel popped right off :) 

- New mainspring installed (yes, by hand, no I don't have a winder yet, yes I wound the spring the wrong way the first time, and no I did not spend 10 minutes looking for a wild barrel harbor that went for an orbital flight... yes I found it :) )

- next step : cleaning and assembly !

[frenchie]

Alright, quick update:

- Santa got me the right presto tool !!!

- Case all cleaned up, crystal cleaned and polished up nicely

- Movement is all cleaned up and put back together, mostly...

- I'm not sure how/if I'm supposed to lubricate the center second pinion (the pinion that goes from the center second drive wheel to the dial, where the second hand attaches). Any advice ?

 

BUT : there is a bend in the balance spring that I had not noticed earlier...  Will try to fix it but I have located a replacement already (I am very optimistic :) ) I've practiced "Fixing" hairsprings on a couple of old beat up practice movements, it'll be my first real one !! (I went from destroying a hairspring in 15 seconds, to taking more than 5 minutes before it broke :) )