EMG Crown DL63

ClaudioCavalli · April 20

I am working on the crown of an EMG DL63. The stem snapped and there is nothing to grab. As a last resort I was successful in drilling a hole in the middle of the broken stem. I was planning to epoxy the filed eye end of a bent needle in the hole to see if I can remove the stem (see first attached image). Now I know this is likely not going to work, but what the heck it is a last resort.

Anyway, as I was heating the crown to release the locking agent my heating plate seems to have malfunctioned and heated up to almost 500C before I noticed and this resulted the chrome to yellow (see second image crown color in comparison to the first one). Am I right in assuming that I can try and reverse the discoloration by buffing it with a little metal polish?

And in case the discoloration removal or stem removal does not work, where could I find a replacement crown? The crown has a a distinctive lock symbol on its face that I would like to keep if I need to get a replacement.

Further I am looking for the size of the two gaskets that are in the crown. I was initially unsuccessful in removing them and I had to soak the crown in acetone to remove the gaskets. I measured the sizes in the third images. Can I assume that is the size of the replacement gasket?

thank you

claudio

ColdWind · April 20

2 hours ago, ClaudioCavalli said:

as I was heating the crown to release the locking agent my heating plate seems to have malfunctioned and heated up to almost 500C before I noticed and this resulted the chrome to yellow

This is a modern watch, the crown is definitely made from solid 316l steel. You must have heated the crown to some 200C caused the surface colour to change to light yellow. It's similiar to steel tempering. Yes it is the chromium oxide that forms during the heating that gives rise to the colours you see as you know stainless steel contains chromium. The fact the crown is SS lead me to a question, you've never heard of the alum method? Because alum would work perfectly in this case, instead of drilling, which, there is always a risk of damaging the crown, I would just let the crown chilling in some warm alum solution for 1-2 days and the job is done.

2 hours ago, ClaudioCavalli said:

I can try and reverse the discoloration by buffing it with a little metal polish?

Sure can but the thing is the crown is not just mirror finishing, the lock symbol is polish while its background is some sand-blasted finishing so it would be hard to replicate that. You can buff it all shiny but losing the sand-blasted finishing means it won't look exactly like before.

2 hours ago, ClaudioCavalli said:

I am looking for the size of the two gaskets that are in the crown

Gasket is always tricky to me. I would try to use some gasket that look closest to the broken one in term of thickness and diameter, and check if the replacement gasket fit with some friction to the case tube.

Lastly you can still use alum at this point.

Edited April 20 by ColdWind
Typing errors

ClaudioCavalli · Saturday at 10:33 PM

Thank you ColdWind,

I did try the alum solution and albeit slow (I am on my third bath of 6 hours at 70° C with a solution of 10ml of water and 2.5g of alum) it seems to be working. I can now screw in the new stem, at least a few turns. I expect that at some point I will be able to screw the stem in all the way. Perhaps next I will try a bigger bath. I wonder if the limited amount of alum is slowing down the process?

An happy side effect of the alum bath is that it removed the oxidation from the crown!!

claudio

AndyGSi · 2025-05-11T05:48:42Z

If you're running at 70° C you can use a lot stronger solution than you've got.

I use around the same strength solution as you and at at 40° C it takes about 5 days to completely dissolve a 0.9mm Dia. stem

ClaudioCavalli · 2025-05-11T05:57:31Z

Thank you Andy,

I will keep that in mind. Fortunately this time, I tried to drill the stem out before finding out about the alum method, therefore most of the stem was hollowed out. When I took the crown out of the third bath, I was able to screw the whole replacement stem in. It us now in the ultrasonic cleaner to get any remaining gunk out.

claudio

Edited 21 hours ago by ClaudioCavalli

ColdWind · 2025-05-11T06:19:05Z

7 hours ago, ClaudioCavalli said:

An happy side effect of the alum bath is that it removed the oxidation from the crown!!

I'm glad it worked out well for you. Must feel good to learn some new watchmaking black magic huh? Can you post a photo of the crown after all this, I'm a bit interested in how it looks compare to how yellow it was before, never thought alum could dissolve oxidation as well, maybe I can work out the chemistry behind it, something to do with the electrochemistry list, but I'm too lazy for it so you are lucky it was only yellow, the layer must be so thin it didn/t damage the finishing enough to be noticeable.