Fabrication And Replacement Of A Patek Escape Arbour

[Horlogerie]

The Patek Philippe pocket watch arrived with a number of problems. The most serious was that the escape wheel arbour was snapped off.

General view of the movement

The broken escape wheel arbor

The biggest problem was that the arbour had broken off flush with the escape wheel pinion, a worse case scenario, leaving me no arbor stub to use as a alignment guide for drilling. So in order to install a new arbor I had to drill freehand with no guide. Here's the escape wheel mounted in the lathe, where I used a grave to cut a center v-notch to guide the drill.

Next up was the drilling, the drill measures 0.25mm in diameter and standard practices is that the hole is 3X the diameter, so I drilled down 0.75mm deep. Holding onto and drilling a hole with a 1/4 of a mm drill is a big challenge, it's only 4 times thicker than a hair, so not much pressure is needed to snap it in two.

Here's a better view of the 0.25mm hole I drilled.

Next up was fabricating a new replacement arbor, I did this using silver steel, and made it oversize so that I could adjust it for a perfect fit. The diameter of the arbor is 0.35mm and the pivot is 0.11mm.

Checking the pivot diameter.

Replacement arbor on top, old broken one on bottom.

A small dab of Loctite was applied to the part of the arbor that would be press fitted into the escape wheel, then the new arbour was carefully tapped in place and seated and aligned.

With that taken care of, the escape wheel was installed in the movement and I measured how much of the tip of the pivot I needed to remove for a perfect fit with the required end shake.

Here's the pivot sticking out of the jewel with the cap jewel removed.

And here's the view with the pivot trimmed in length and sitting just below the jewel.

There were a number of other issues with the movement, but I always start with the most challenging. With the new arbor in place and the escape wheel fixed, I went on to the other defects, which will have to wait till another day.

[Geo]

Excellent job and illustrations, this is the kind if thing that floats my boat! :)

[clockboy]

Excellent work Horlogerie.  Did you find the silver steel cut ok. I recently read it is OK to also use blue steel for pivots & balance staffs. Just wondering what your preferred option would be.

​PS I have read you articles in the BHI with great interest.

[mwilkes]

Fantastic post! How did you shorten your pivot safely?

[Horlogerie]

Excellent work Horlogerie.  Did you find the silver steel cut ok. I recently read it is OK to also use blue steel for pivots & balance staffs. Just wondering what your preferred option would be.

​PS I have read you articles in the BHI with great interest.

 

I have no problems cutting the silver steel, mind you I tend to use a carbide graver sharpened to a fine razor edge. But, I also can cut silver steel with a standard graver with no problems. The silver steel is tempered to what would be a "blue" steel hardness, before I cut the arbour. It is OK to use pre-blued steel for pivots and balance staff's, but what I have found is that "blued" steel you buy from the various vendors is not tempered properly, so I prefer to use my own.

Thank you for the BHI feedback, much appreciated, hopefully you will like the April issue. The only drawback is that you will see some duplication between the HJ and my posts.

 

Fantastic post! How did you shorten your pivot safely?

I used my Jacot tool to shorten the tip, with the escape wheel safely mounted in the Jacot tool, slowly and carefully I removed material with a arkansas fine stone, then rounded and burnished the tip. It's a tricky process but if you mount the wheel properly the tip is supported by the lantern runner.

[clockboy]

Thanks I have looked at the carbide gravers but they seem a devil to sharpen. I take it you temper the Silver steel yourself.

I'm now looking forward with extra interest to my April BHI

[Horlogerie]

I also find the carbide gravers difficult to sharpen, but I finally stumbled on using a India Stone for the sharpening, and it works really well. I have the double sided India stone, with fine and co**BLEEP** surfaces. I also have a fine diamond wheel that I mount in the lathe and it works very well and is able to give a nice flat finish to the cutting edge. Between the two, I can finally achieve a flat sharp edge.

I do temper the silver steel, this is the only way that I can get consistant results and hardness.

[clockboy]

Thanks Horlogerie, This the one area where I do need to improve on, that is making parts & this is really useful information.

[autowind]

Making new parts takes watch repairing to a whole new level,  I admire your skill.  A Patek Philippe has got to be worth saving at almost any price,  thanks for the excellent write-up.

[bobm12]

Excellent post and fix! Hats off to you Horlogerie!

[icius]

That's some amazing work there. Thanks for sharing it and welcome to the forum

[atimegoneby]

Making new parts takes watch repairing to a whole new level,  I admire your skill.  

 

Couldn't have said it better myself.....  amazing stuff !  

[Michael]

Love the post. Great to see so much knowledge and skill. What type of drill bits do you use as I had a quick look on Cousins and they don't go that small. I have broken  plenty of pivots and centre shafts, so one day hope to have a go at repairing

[RicardoG]

Hi Robert and everybody. Again my congratulations for this nice job.

Jus a question: Where did you get the raw material for the arbour? Did you use something like a sewing needle?

Ricardo

[Horlogerie]

Love the post. What type of drill bits do you use as I had a quick look on Cousins and they don't go that small.

 

Thank you for the positive feedback.

I find that material house drill bits are very expensive. What I use are carbide drill bits, you can buy them on Ebay, they are used in the electronics industry to drill PC boards and then they are sold at really cheap prices. I have a few hundred in various sizes and love them. If you search under those words you should find a number of sellers.

 

Hi Robert and everybody. Again my congratulations for this nice job.

Jus a question: Where did you get the raw material for the arbour? Did you use something like a sewing needle?

Ricardo

Thank you for the comment.

I bought the silver steel, and all my metal stock (silver steel, stainless, and brass) from the suppliers to the model engineering hobby. There are many of them in the UK, I have used a few of them, GLR Kennions www.glrkennions.co.uk is one example. They carry a wide selection of metals that are perfect for the watchmaker.

[Mark]

Brilliant job - I always find drilling these out to be the most difficult part.

This is a tricky job and you seemed to have nailed it!

[Horlogerie]

Brilliant job - I always find drilling these out to be the most difficult part.

This is a tricky job and you seemed to have nailed it!

Thank you.

I also have difficulty drilling these small holes, I love the carbide drills for their cutting action, but they are so brittle compared to HSS drills that it's a real challenge between maintaining enough pressure so that you don't burnish the hole, and not too much pressure where you snap the drill off inside the hole. Removing a broken carbide drill from a hole is not something I enjoy doing. I hold the drill lightly in my fingers so that I can feel how it's working and if it does catch it will slip in my fingers and not snap off like it would if held in a chuck.

[Mark]

Have you tried the carbide spade drills? These are great for getting the hole started.

[Geo]

I hold the drill lightly in my fingers so that I can feel how it's working and if it does catch it will slip in my fingers and not snap off like it would if held in a chuck.

I've only done a couple of re-pivoting jobs and both were using carbide twist drills. At the time I did not have a tailstock with a runner, so both were done using a chuck. It's best described as mating hedgehogs! I have since managed to pick up another tailstock with runners, so hopefully it won't be so heart in the mouth the next time.

[atimegoneby]

My father worked in a carburetor factory during the 1960's, he used very fine drills for drilling carb jets and housings, etc, I still have these in sizes 0.5 mm & smaller, the quality is excellent.    May be an area to check for supply ?

[Horlogerie]

Thanks for the reply Mark, under normal conditions, when I have an arbour remaining that I can fit into my tailstock drill runner, I would use a spade drill. But in this case because I had nothing to ensure that the drill would remain centered, other than the shallow v-grove that I cut into the broken arbor, I was concerned that the spade drill bit would go off center. So I felt it was better to use a twist drill with a nice point that would keep centered in my v-grove.

The tailstock runner is the safest way to do the drilling for sure, and even then I still use my finger holding method so I can feel what is going on.

Edited March 25, 2015 by Horlogerie

[WillFly]

What a great demonstration of skills and technique, and I can only let my jaw drop in admiration. I like tinkering with watch movements and doing minor bits to them - but I look in the mirror and see a boy who consistently came bottom of the woodworking class at school! :bow:

[frenchie]

Amazing !!!

And welcome to the forum !

[Lawson]

Your macro pictures are so good Horlogerie, that they don't do justice to just how small a tolerance you are working.

Drilling quarter of a millimeter precision holes is NOT for the faint at heart :huh:

 

I'm looking forward to reading many more posts of your fine workmanship in the future mate.