Oversized stem

[steve1811uk]

Hi Everyone, looking for some help with oversized stems. I have an AS1123 movement and the stem keeps pulling out. I believe that is due to wear in the mainplate as the stem can wiggle around. I have bought a selection of 'oversized' stems but wondered how I can bring the stem hub diameter down to suit as it is unlikely that it will fit without some adjustment. I have no access to a lathe and was going to mount the stem in a Dremel type tool and use some kind of abrasive or file. Has anyone done this or have any thoughts?

[nevenbekriev]

First of all, what 'oversized' means here? Does the winding and sliding pinions enter on their places on the stem? If so, may be only the holes in the main plate should be reamed to accept the stem?

[steve1811uk]

It is only the hub, the part that engages with the setting lever, that is oversized.

[nevenbekriev]

Then the answer is in my first message.

[steve1811uk]

Thank you, I think that could work but ideally I wouldn't want to take material from the mainplate if there was another option.

[nevenbekriev]

OK, but first what is the reason why the stem You have 'keeps pulling out'? Is it wear of the setting lever, the retaining screw/hole, the hole in the plate for the stem? Is there a danger that if You reduce the 'hub' diameter, the new stem will start pulling out too? Yes, the hub diameter can be reduced not using lathe, just pin vice and good hand grinding tool needed, but some dexterity and skill needed too for good result.

[steve1811uk]

1 minute ago, nevenbekriev said:

OK, but first what is the reason why the stem You have 'keeps pulling out'? Is it wear of the setting lever, the retaining screw/hole, the hole in the plate for the stem? Is there a danger that if You reduce the 'hub' diameter, the new stem will start pulling out too? Yes, the hub diameter can be reduced not using lathe, just pin vice and good hand grinding tool needed, but some dexterity and skill needed too for good result.

It's the hole in the mainplate that has become too big due to wear. I will try with some fine abrasive paper wrapped around a small file. I will start with 3000 grit and see what effect that has.

28 minutes ago, steve1811uk said:

It's the hole in the mainplate that has become too big due to wear. I will try with some fine abrasive paper wrapped around a small file. I will start with 3000 grit and see what effect that has.

Or I could try with a homemade burnisher. Anyway, I will post the result here soon.

[CYCLOPS]

sometimes the barrel bridge is rubbed too, causing more movement, I assume as said above the setting lever is like new? you can get a small chuck to hold it in your Dremel like you said fine abrasive/grit, might be difficult to keep even, good luck anyway......

[steve1811uk]

Thanks for the replies. I did the job today and found that the oversized stem fitted just perfectly into the worn mainplate without any adjustment. Original stem diameter was 1.24mm and the oversized was 1.40mm. I did have to make an adjustment to the setting lever though. The small pip that engages with the groove in the stem hub was slightly to wide. I made that a bit smaller with a fine file. Don't ask me why that was too big, it just was. All working very well now. No wobble and not pulling out. New crown fitted as good measure.