Stem extension help

[Chopin]

I have to use a stem extension on a Seiko Diver's with a screw down crown and I have some questions as I've never done this before.

First of all, how do you tighten the stem to the stem extension ? I know that I'll probably have to use a bit of glue but what do people do to tighten it ? Do you use a small vice ?

Second of all, I know that I'll have to cut it to length but how does one do it ? Trial and error ? Measure an approximate length and then just shorten it bit by bit until you get it right ?

Edited January 8, 2018 by Chopin

[WatchMaker]

I"ve used these before to good effect. I just put a crown on the extension and a drop of glue on the original stem. Now holding the original stem in a pair of pliers twist the extender on using the crown to screw it on. You don't need to use a lot of force. 

In terms of then shortening your new extended stem then approach this no differently than you would a normal stem situation. This is a great posting:

It''s sometimes necessary to shorten the original stem so that when the extender is fitted and shortened there's appropriate thread on the extender to fit the crown. Trial fit everything before the drop of glue!

[Chopin]

That is one method that I was thinking of... Thanks!

At first I'm going to try and just trim the extension and see if it works, if not then I guess I'll have to trim the stem as well.

Another question which I forgot. How and what do you use to cut the stems and extensions ?

I don't have any special such tools but I do have the tools that you'll find in a normal household... Hope I have a pair of cutters with good blades...

[digginstony]

That is one method that I was thinking of... Thanks!
At first I'm going to try and just trim the extension and see if it works, if not then I guess I'll have to trim the stem as well.
Another question which I forgot. How and what do you use to cut the stems and extensions ?
I don't have any special such tools but I do have the tools that you'll find in a normal household... Hope I have a pair of cutters with good blades...

You may get away with just trimming the extension. As mentioned by "Watchmaker" Geo's article is just about the definitive work on this subject.
Wirecutters for the stem but the type you cut straight onto rather than to the side of the stem are best.
Try Cousin's or Esslinger, as they stock replacement stems suitable for Seiko that are threaded their hole length and makes life a lot easier

Sent from my SM-T585 using Tapatalk

[WatchMaker]

I have a pair of straight cutters ... nothing special e.g. item P36103 from https://www.cousinsuk.com/product/end-or-top-straight-cutters# . You could use normal cutters just above the desired cutting mark and then gently file down any 'peak' caused by a non-straight cut to your mark. Because extenders are so cheap (around a pound for five) you can always practice on an extender itself i.e. cut and file on an extender and then check another extender will easily screw on. This may be a better option for you than buying special cutters if this is a one off job.

 

[Chopin]

I do have extra extensions and an extra stem, just in case, but I'll try not to mess it up. Wonder if I have any good files... Could sand paper work ?

[digginstony]

I do have extra extensions and an extra stem, just in case, but I'll try not to mess it up. [emoji3] Wonder if I have any good files... Could sand paper work ?

Sand paper [emoji16][emoji16]. You'll need a decent fine cut file. Remember when sized, to bevel the tip. This prevents stripping the thread on the crown when screwing on.

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[clockboy]

Mark has a vid on this job but I have attached another vid from Esslinger. The guy uses the same method I use but I secure with loctite not glue just in case it has to be removed in the future.

 

[Chopin]

I've seen these esslinger vids but they're not as thorough as Mark's are... Thanks nonetheless. Could I use GS Hypo as glue ? I believe it can be removed with isopropyl...

[MrRoundel]

I just watched Mark's video on stem replacement. I agree wholeheartedly with Chopin's comment. Since I just watched it, I have the link handy:

Watch Repair Channel's Tutorial

[Chopin]

Well, the good news is that I've managed to do anything required. The bad news is that with the extension (even trimmed out) the crown is now too long and I also broke the stem inside the crown.

Now I have to buy a new crown and stem as the old one didn't seem to actually fit, length wise, especially since I tried a brand new stem and it was a bit too short.

Oh well...