Here’s what I started with. I’ve seen similar ‘push/ tension fit’ movements holders before (obviously they’re used widespread). This one lacked the usual protruding flaps/ teeth that would create tension when the screw back was tight, forcing the movement/ dial etc. Into a ‘semi locked’ position. My watch originally came with a 2813 movement and I went to a A2836.
here it is with the A2836 installed. It’s probably designed for the 2813, but even when that was installed in it, it was horribly loose. When the crown was unscrewed, the movement would wobble around terribly. With the crown screwed in, it would hold position, but was still very unstable, and was not level in the case.
Here’s an old A2836 ‘mounted’ in it:
next up is the (cheapish) plastic ETA 2824/ 2836 movement ring. These are available widely on the popular auction site etc.
that fitted in the Silix case well (much better than the above), but the movement would still want to move about when the crown was unscrewed. I tried (in vain) to get movement tabs to get purchase on the inside of the case, but no joy. The holder/ ring itself was fine though. It had a much more professional level of construction, and fitted the 2836 well.
along the way, I had purchased a brass movement ring. This didn’t ‘grip’ the 2836 in the same way as the above, but it was nicer to look at, and felt better!
I resolved that either of these holders was fine, and that it was the movement tabs that were the real problem. So...I sat everything in place as I wanted it, and used a very fine marker to draw a line where the tabs needed to engage in the case. I then removed everything, and used masking tape to protect the inside of the plexi/ case etc. (I could have removed the plexi, but didn’t think of this at the time!).
Next step was to work very carefully/ minimal coffee/ lots of light & used a very small/ fine cutting/ grinding disc on my dremmel to cut a very fine ridge/ Chanel inside the case where I needed the tabs to engage. I was careful to avoid cutting into the threads for the caseback, and went very slowly to make sure that I didn’t cut through anything that I didn’t want to. I haven’t got any pictures of that part, but here’s the finished result. I ended up getting a watchsmith to assemble (
ado213 as items to mess up hand mounting ), but have since disassembled and reassembled myself a few times, and it all goes together fine now.
Hopefully you can see what I mean-you can still see my black marker marks left as a guide. This is with the brass movement ring from raffles on the big auction site.
hope that helps in some way. There are probably loads of other ways of achieving this, but this route (cutting into the case for movement tabs) made sense to me.