How to repair a broken pusher

[anthonyd 0]

Hoping for a sticky here Here's what I did over the last three days after an unfortunate accident:

 

Ok so in an attempt to try to make my Breitling 6.75 waterproof I deicded the pushers needed to be removed and new O-rings put on them.

 

As you can see from the picture below there is no indication of any sort of clip that holds the pusher in:

The image above is taken with the pusher fully depressed.

 

So looking at it from the side here I decided it muct be a screw type arrangement:

 

 

I grabbed the pusher with a pair of pliers and turned. Much to my amazement it turned just fine and the pusher came off. Then I had an Oh shit moment when I realise the pusher was infact broken:

 

 

Taking a careful look I realise that there is actually an insert that seems to be press fitted into the case. I assume that the pusher is assembled into this insert, the C-clip added and then the whole assembly press fitted into the case, making it impossible to remove the pusher once it is in.

If you look carefully down the hole here you can see the insert:

 

So anyway I was stuck with the following which needs to look like this, but be assembled back into the case:

 

Clearly trying to glue the pieces back together is not an option, this would be what woodworkers call a butt joint, one of the weakest glue joints. What I needed if for the piece with the red circle above to be recreated with a spiggot on it. The remaining piece then needs to be drilled out so that the spiggot can be loctited back on.

 

Here's how to do this:

 

Firstly let me start by saying I have no formal metal machining training, I am self taught and onyl know what I know from experience and reading around. If and real machinists feel i I have any facts here incorrect please let me know and I will edit this post.

 

Also you will need a lathe of some sort, I really dont think it is possible without one. I use the famous chinese 7x12 mini lathe which, if adjusted correctly can be very precise.

 

So I did what I always do when doing any sort of machining, I first drew it up on a 3D package.

 

This is what we want to create:

 

 

But before we start, this project hinges on our ability to drill out the existing piece. Since I do not have a replacement part here this can only be attempted once. If you screw this up, do not dispare, I have an idea on removing all the material inside this cap and the creating a female mating part that can be glued into it, but thats for another tutorial.

 

I mounted the end cap on the lathe, making sure to get it running with near zero runout. We will be drilling a 0.7mm hole in a part that has a diameter of 1mm. That leaves only 0.15mm of leeway on each side, so if we have a runout of 0.1mm the drill will break through the sides.

 

 

I used a HSS drill bit, starting at 0.5mm (because my chuck will not hold anything finer) and advancing in 0.05mm steps up to 0.7mm. Depth is 2mm.

Drilling is done at a relatively high speed (around 1000rpm) but the drill is advanced very very slowly, remember this is probably stainless we are drilling. The bit was also removed every 0.025mm and more cutting fluid applied.

 

 

And after all of that we have success:

 

 

Pat yourself on the back, the scary part is over.

 

I then decided the turn the remaining part out of brass, the reason for this is because brass lends itself better to machning very fine parts. Due to the small size here we cannot use a centre on the lathe turret and since we are only tuning lenghts of under 2mm a travelling steady is totally impractable.

 

It is a good idea to start with a nice thick piece of brass so that there is a good solid support for where you will be turning. If you try to turn a 2mm piece of brass down to 0.7mm about 10mm away from the chuck the stock will just end up bending away from the knife and you will end up with a taper going from thick to thin. You definitly dont want this! Starting with a thick piece of brass and turning the end down to 0.7mm will mean that the small 0.7mm piece is nicely supported by the large diameter stock.

 

I used a piece of brass scavanged from a tap, it is about 8mm in diameter. Here it is mounted and faced in the lathe:

 

 

Here we start turning. Note the shape of the knife. I ground a new knife out of HSS for this job. Often the cutting point is rounded as the last part of the grinding process. This gives a nice finish when machning but puts more stress on the stock when cutting. Since we are not interested in the finish but rather in the precision of the cut I have ground this knife to a very sharp point. Apparently this is recommended for small diameter work like this.

 

 

When you get down to about 1mm diameter take very shallow passes. My lathe's cross carrige has gradient markings in 0.001" (0.025mm), towards the end I was using half a gradient per advancement. It is also a good idea to do multiple passes of the knife for each advance forward of the knife. This will allow for any flex in the stock.

 

After about 15 minutes on the lathe success:

 

 

 

And here with the outside pusher pressed on:

 

 

 

Note how I ensured that there is a gap between the body of my new pusher and the end piece. In this gap the spiggot is exposed. This will serve at the placeholder for the waterproofing gaskets.

 

Now simply press the new pusher into the case from the inside, and add a bit of loctite to the end cap. I used loctite 638 which is a bearing retaining compound, but loctite blue or red would work just as well.

 

Voila - watch fixed:

 

 

 

[Nisv 0]

 

You know you'll have to become a TD here now offering customized pushers, right?

[anthonyd 0]

 

You know you'll have to become a TD here now offering new pushers, right?

 

 

I rather spend my time warning folks not to try to forcefully remove them

 

I'm just glad I got it fixed. This watch has an unlucky history:

 

I bought it from a member here are month or so ago. When it arrived the movement was unreliable and kept stopping. The seller assured me this was not the case when he owned it. I decided to stip down the movement and try to lubricate the sec at 3 drive train. While removing the minute counter hand, the entire hand stem came off with the hand!!!

 

I then decided the watch should be scrapped and bought another 6.75 from Mary. After a month of looking at the broken watch, I coudl not stand it and ordered a new movement from Mary along with a white face (original one had blue face as did the replacement I ordered.)

 

The movement arrived last week, I installed the face and hands and, while putting it all into the case I decided it would be a great idea to waterproof the pushers

 

The rest is emaplined above. I swear, that caseback is not every being removed again

[Nisv 0]

Well, hats off to you, Sir

It's always good to read about successful DIY repair adventures, especially where handmade parts were used

[onionbag 1]

Well done anthonyd, an elegant solution to a tricky problem. Speaking as a machinist your approach to the task was meticulous and thoughtful, I'm very impressed.

 

One wee tip, when turning tight tolerance diameters I never trust the machine scale, I use a dial test indicator set against the tool post to give me an accurate reading of the depth of my next cut.

 

I hope you get a sticky and look forward to the next instalment.

[pollux1 3]

Fantastic write up, the level of workmanship is astounding.

[anthonyd 0]

Well done anthonyd, an elegant solution to a tricky problem. Speaking as a machinist your approach to the task was meticulous and thoughtful, I'm very impressed.

 

One wee tip, when turning tight tolerance diameters I never trust the machine scale, I use a dial test indicator set against the tool post to give me an accurate reading of the depth of my next cut.

 

Thanks onion.

 

Yes the machine scales was not really relied upon. Towards the end I was measuring with a micrometer after every pass. I like the DT idea thought, I would just need to fashion a mount for it.

 

I cant say this idea was truley my own.

 

A small while ago I bought a new rotary table from a local machining shop for a good price, however is had had a fall and the hand wheel was stiff to move. Turned out that the 10mm steel shaft had been bent. When I asked a machinist and machinery supplier if he could source me a new shaft he had the idea of cutting off the bent section and rebuilding it, then joining it to the straight piece (I could not make a whole new shaft as the end had a worm gear which i way out of my skill level). He suggested the idea of using a spiggot on one end and a hole on the original piece. I successfully did this and pinned it instead of loctiting it, but his idea was the brainchild behind the one I outlined above.

 

Regarding the next installment, well that was really only if i failed to drill out the original pusher, so it is probably unnecessary, and given my history with this paritcular watch I am reluctant to experiment any further

[WebWind 1]

Great work

[robznet 0]

Superb job mate - well done!

[MikeMcNair 0]

:yoda:

 

You know you'll have to become a TD here now offering customized pushers, right?

 

 

considering i just deleted the "you've got a PM" emails from only the last week, and it was over 212!!!!! i'm gonnna say he has more to do with his time than be a TD lolololol

[myaz 3]

I love how it reads: pusher is broken, I pull out the lathe, grind another one, insert it back in and voila. Holy excrement!

For a nano second, I started to think something like that is doable if only for the lack of a lathe. Then I woke up.

Great and interesting tutorial.

[anthonyd 0]

:yoda:

 

You know you'll have to become a TD here now offering customized pushers, right?

 

 

considering i just deleted the "you've got a PM" emails from only the last week, and it was over 212!!!!! i'm gonnna say he has more to do with his time than be a TD lolololol

 

 

Do what I am doing mike. Next month I will be movinh to South Africa, bet most of the people sending you PM's would not be keen to post their watches there for services

[anthonyd 0]

I love how it reads: pusher is broken, I pull out the lathe, grind another one, insert it back in and voila. Holy excrement!

For a nano second, I started to think something like that is doable if only for the lack of a lathe. Then I woke up.

Great and interesting tutorial.

 

Myaz, I am by no means a competent machinist. I have only had my mini lathe for about year, so this is well within most people's reach if they ahve a lathe. Careful, collecting metalwork tools is as addictive as watches.

 

Then again, if you referring to lathe work as "grinding another one" maybe this is a but above you :yoda:

 

For the record a lathe cuts, not grinds. It is highly frowned upon to use grinding attachments on lathes as the fine grinds can cause havok with the lathe.

[powderfreak 0]

Wow, that was an amazing writeup, you have a talent for fixing stuff - unlike me, I am a pro when it comes to destruction and breaking watches :yoda:

[Luthier 1]

Yeah, sure, we all can do it, and we all have lathe and proper skills.

:yoda:

Great job, Anthony!

[myaz 3]

I love how it reads: pusher is broken, I pull out the lathe, grind another one, insert it back in and voila. Holy excrement!

For a nano second, I started to think something like that is doable if only for the lack of a lathe. Then I woke up.

Great and interesting tutorial.

 

Myaz, I am by no means a competent machinist. I have only had my mini lathe for about year, so this is well within most people's reach if they ahve a lathe. Careful, collecting metalwork tools is as addictive as watches.

 

Then again, if you referring to lathe work as "grinding another one" maybe this is a but above you

 

For the record a lathe cuts, not grinds. It is highly frowned upon to use grinding attachments on lathes as the fine grinds can cause havok with the lathe.

ooops. Thanks for the correction.

[anthonyd 0]

Wow, that was an amazing writeup, you have a talent for fixing stuff - unlike me, I am a pro when it comes to destruction and breaking watches

 

 

Lets not forget who broke the pusher in the first place by twisting it with a pair of pliars

[greg_r 81]

How did I miss this? Great post!

 

Here, have a sticky

 

[part_timer 0]

Damn good job there!

[tissotman 0]

You will be designing your own watch next! You certainly have the ability