QUOTE(wimg @ Feb 20 2008, 08:27 AM) [snapback]520438[/snapback]
Well, all Etruria nibs are friction fitted, yes, but also all are fitted with a (screw-in) collar. As far as I can tell, all of your Etrurias have a removable screw-in nib/feed assembly, provided your Amber is not the older model, but the 2006 version. The older (up to 2002 I think) Amber has a glued or cemented in nib/feed assembly, as the collar is fixed to the internal piston mechanism, and as a result you can only remove the nib and feed by pulling it. The visible difference between the old Amber PF and the new Amber PF is the section, which is more or less straight tapering with a lip in the older version, and a curved section in the newer. Of course, the Amber Convertible has a different clip

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Warm regards, Wim
Interesting. I found a similar collar with my Omas 360.
http://www.fountainpennetwork.com/forum/in...showtopic=51405The first time I took it out, I was able to unscrew (with alot of brute force...) the nib/feed/collar assembly. After reinserting, I tried it again. This time, when I pulled/twisted on the nib, the nib/feed came out, but the collar stayed in the pen.
At the LA pen show this weekend, I purchased a fine nib from John Mottishaw, and had him insert the new nib. I watched him do it, and essentially, he took a rubber coated plier and pulled out the nib/feed then replaced the tip and fit it back in.
I am guessing that the purpose of the collar is to prevent wear on the pen itself?
I don't plan to exchanging my nibs anymore, but it is nice to know that if I decide to go back to a medium nib, I can do it myself.