I'm servicing a Valjoux 7733 based Tissot 20700 chrono and so far it's been fairly standard and no surprises.

However...

I found a basic tech guide on the webs which was quite helpful, but when it gets to removing the chrono driving wheel is simply states: "Remove the driving wheel No. 8060, using a suitable tool."

"Suitable tool" can cover a multitude of options, depending on the mentality of the user, so any watchmakers with experience removing this component?

And what "suitable tool" was used?

The offending item.



The top of the wheel arbor has a groove that may be to provide a grip for a "lifter". The wheel appears to be pressed onto the fourth wheel pivot.

Any guidance appreciated.

@Archer, @ChrisN, @Deafcon, @Canuck, and anyone else who would like to advise.

 

Morning Jim

These driving wheels are indeed pressed on to the wheel extended pivot and you see them on many chronographs as well as other calibres where they can be used to drive a sweep seconds pinion.

I use a Presto for lifting these as it gives a straight pull.
https://www.cousinsuk.com/product/5-spoke-wheel-remover-bergeon

I also have an odd "wobble" tool which was recommended to me but that seems far harder to work with.
https://www.cousinsuk.com/product/wheel-hand-roller-remover-bergeon

Some people do add protection to the bridge and then slide in two identical screwdrivers opposite to each other under the wheel centre. Rotate each the same amount in opposite directions and you should get an even lift. This is far more difficult to do successfully though and I wouldn't recommend it.

Cheers, Chris

 

I use the Presto tool. You can use levers (rather than screwdrivers), but you have to be sure to lift each side equally, or you risk bending the post the wheel is pressed onto.

 

The Presto tool mentioned by @Archer is the only way to go re: removing those drive wheels, (IMO). This tool acts just like Presto hand removers. They have claws which fit beneath the wheel, and three “quills” which protrude downward to contact the bridge beneath the wheel. This tool is available with three quills for use on wheels with an uneven number of spokes, and four quills for wheels with even spoke count. Once in place, a deft squeeze and quills protrude downward, and the claws lift upward to lift the wheel off. Prying that wheel off can result in embedding the wheel in the ceiling tiles above your bench, or breaking the pivot off. Not to mention scarring the wheel and the plate.
The tool.

 

@ChrisN, @Archer, @Canuck

Thanks for the advice gents.

I was reluctant to even think of levering it off and thought I had a Presto, but it's an old broken hand remover, not a wheel puller.

My Aussie supplier stocks them, but as usual, when you need something, it's out of stock.

I might modify the old Presto to use as a straight up lifter and see how that goes.

 

Other suppliers might have it readily available. I think you’d be better biding your time, and getting the sweep wheel puller, rather than trying to convert a hand puller. The sweep wheel puller is a must in my opinion. Particularly when working on older calibres.

 

Unfortunately suppliers are thin on the ground here but I'll try a couple of others here, may end up having to go Europe or UK though.

I'll give my supplier a call on Monday and see if it's a computer stock issue or a real stock issue.

 

Could you maybe borrow a puller from a member of the fraternity, nearby? I guess chances are slim and none!

 

You guessed right . Our local fraternity is as rare as our suppliers, and I suspect those that have the tools may be reluctant to loan them to a relative stranger.

A quick question.

The wheel is a 3 spoker, so a six spoke puller would work, but I think a five spoke puller would also work.
Or is my thinking off track.

 

These drive wheel generally have an uneven number of spokes. Some have an even number of spokes. These Presto pullers come in two models. One model with three “quills” for wheels with uneven spokes. The other has four quills for wheels with even numbers of spokes. I have never had need for any puller but the one designed for wheels with uneven number spokes. I’ve shown a picture of mine with the three quills deployed. One spoke of the wheel fits between two quills, and the third quill fits between two spokes. The tool works just like Presto hand removers. Orient the tool over the sweep wheel as described, and as you squeeze the bows, the hooks close under the wheel, and the quills extend downward between the spokes as shown in the picture. The quills contact the plate beneath the wheel, and as you continue to squeeze the bows, the wheel lifts off. Simple!

 

After looking at this again I came to the conclusion that a wheel lifter would not work (properly) as there isn't enough clear real estate on the bridge below the wheel where the quills would push down.

That's probably why Valjoux added that little knob on the top of the wheel. So after thinking about it I found a pair of fine angle cutters and modified the jaws a bit to allow me to locate the cutters on the knob. I would have preferred end cutters, but don't have any fine enough.



I then gripped the wheel and holding the movement down with one hand and using a finger under the jaws to try and even out the lift, pulled up as straight as possible with the other hand.

And promptly whacked myself in the face!

But success, the wheel is off and no bent pivots or broken jewels.

 

There's another very "interesting feature" of this movement that I'll share later.

I found it after removing the escape/fourth wheel bridge.

Any guesses?

 

I doubt it, in the valjoux there is a lot of space between the wheel and the bridge, much more than on a flat indirect second three hander.

I personally don't like the presto much and have made a pair of custom levers, but in this case I think it works fine.

 

I mean the space available for the quills of the Presto to push down on.



But you're right about the space between the wheel and the bridge. Another reason why the Presto might not be able to do the job properly, but I'm only guessing there.

A tailor made pair of lifters would work due to all that space. Or even lifters with little cam like lobes at the tips that you could turn to lift.

 

If you can't have a presto, custom levers work well. Just polish the underside so that they don't scratch the plate, and be sure to lift the same way for each or you may bend something. The good thing is you can apply the right amount of pressure, the presto is a bit more make or break. I've had problems in some special cases.

It will avoid you a black eye anyway, you can't smack your face with them

 

I'm loving this blow by blow (literally) description.
LuckyLes

 

A tiny wafer of this steel spring stock can be used to bridge the gap between the bridges which allows the Presto remover to work just fine. I do that regularly.

 

I've never had a problem using the Presto on the 7733 or related movements. It's really a non-issue.

Hope your face is okay!

 

You should have seen me before I had my nose job!



I mentioned earlier an issue I encountered and it's this.



After I removed the chrono wheel and the bridge I thought I was almost done. Not so said the little Valjoux elf.
The third wheel bridge protrudes over the fourth wheel.
I thought "I'll just tilt it as it comes up and it'll be fine" (and the little Valjoux elf snickered).





Even with the wheel lifted as far as I dare, and tilted to the max, the seconds hand pivot is still engaged deep within the jewel (even protruding on the other side of the plate.



Am I doing it wrong?
Are there secrets from the "Académie Technique de Valjoux" that I'm not privy to?

At the moment I intend to treat it like a balance (clean on the plate) and clean the jewels etc as best I can manually, put the bridge on and put the plate through the cleaner as an assembly.

Advice once again greatly appreciated.