Hello,

I have a Vintage Speedmaster 321 crown Old Logo straight lugs. Unfortunately the stem snapped and now it is inside the tube.

Any ideas on removing the stem?

 

Prescription? New stem and crown.

 

The broken stem can be dissolved out of the crown using a mixture of alum and water. Here is an example with the stem broken off inside the crown:



You dissolve as much alum in warm water as the water will hold:



Place the crown in the solution, making sure that the solution is in contact with the broken stem. Periodically clean out the black residue that builds up in the tube:



May take a couple of days since the surface area is small, but I have saved countless crown using this method. Simple and cheap save...

Cheers, Al

 

found this info online:
Alum solution has the property of dissolving steels while not affecting aluminium or base metals, and can be used to recover workpieces made in these metals with broken toolbits lodged inside them.

 

Alum will not dissolve stainless steel, so it works fine for removing a carbon steel stem from a stainless steel crown...I've done it many times.

 

I had the same problem with a Rolex sub crown snapping at the end. Big$$$$$ to replace it,

I left it in apple cider vinegar for approx one week and it dissolved everything out and crown was as good as new

 

I am going though some old parts. I found these Omega Speedmaster crowns. The one on the left is from My Ed White (it was in the bag of parts when I bought the watch) and the one on the right is from my -69 SW, also in the bag of parts.

How can one tell if a crown is reusable?

Can the one on the left be reused? I suspect it cannot.

The one on the right looks as though it is reusable.

I don't want to assume that neither are reusable, even though each were replaced at service.

 

@Taddyangle, pics of the other side?

 

The one on the left appears to have most of the post broken off, but the right one looks okay to me.

Cheers, Al

 

I’ve never used alum for dissolving steel, but the logic is sound and reports are favourable.

Another challenge with old crowns is replacing the seals. I do this frequently when restoring old watches but it’s not always a success. I pry the washer out carefully, clean out the old seal, then fit o rings as required. The O ring has to seal around its outside edge besides sealing oto the pendant tube so it needs to be a snug fit. The washer can be replacedby carefully staking it, if it’s dished very slightly it’ll grip around its edge and stay in. I usually use a tiny bead of epoxy adhesive as a safeguard.

If the washer will come out relatively easy without distorting it’ll generally go back in.

Paul

 

That alum trick is very cool. Bill Nye the watch guy. I have had some luck in the past with shaving off the top millimeter or two of the tube, enough to allow for getting a hold on the piece of stem and unscrew it. This works much better with a long tube. From some of his posts, I take it Archer is a watchmaker. Too few of them around these days.

 

I use the alum trick very often to remove broken srews. Takes some time but the results are great.

 

Around these parts, he's not just a watchmaker, @Archer is THE watchmaker

 

I will probably never have to do this but this is pretty handy to know anyhow! The knowledge base here never ceases to amaze me!

 

Well, I'm glad we know how to remove a broken stem piece from a Speedmaster crown.

Now, what method is used for every other watch on the planet?

 

Goldsmith’s “pickle” solution also does a good job. I’ve used it on crowns, and watch movement components (with broken or rusted screws). Just use some judgement about immersing anything with steel parts you wish to re-use. Alum is more readily available.

Has anyone had experience using a wax resist to protect steel parts you wish to preserve? Might be a worthy experiment.

 

There are certainly plenty of products that will work - if you want to spend the money to buy Vissin from Bergeon (Bergeon 4503-0050 - about $30 for 50 ml) you can, but I can buy a lot of alum for the same price from the local bulk spices store.

And if alum has surface area to work on the parts, it really does work quite fast:

No need to go to the trouble of using wax to mask - often you can hang the part so that only the steel you want to dissolve is submerged:



If that's not possible and you don't want to bother removing steel parts that you don't want dissolved, then just using some silicone grease to coat those parts will work fine.

Cheers, Al

 

I should probably just ignore your Speedmaster babbling, but for the sake of clarity I will point out that the example I have shown in the posts above is not from a Speedmaster...