Parker 51 clutch ring oddness

[Flounder]

I've posted this up on FPN too, its a bit of a weird one but I hope someone can help shed light on this.

My latest 51 vac is ready for reassembly, I'm itching to start using it after all the cleaning, polishing, and painting, but this clutch ring is making me wary!

Side A has a smooth inward slope after the hood/barrel mating surface. I've seen plenty of these.

Side B has a raised lip on the inner circumference of the mating surface, which is giving me pause. Won't that dig into the lucite? Side B also has an internal groove just after the mating surface. I've seen one other clutch ring with such an internal groove, but never a lip on the mating surface.

Why are the two sides different? Should I smooth out the lip, or leave it alone - does it have a function?

[grandmia]

I've posted this up on FPN too, its a bit of a weird one but I hope someone can help shed light on this.

My latest 51 vac is ready for reassembly, I'm itching to start using it after all the cleaning, polishing, and painting, but this clutch ring is making me wary!

Side A has a smooth inward slope after the hood/barrel mating surface. I've seen plenty of these.

Side B has a raised lip on the inner circumference of the mating surface, which is giving me pause. Won't that dig into the lucite? Side B also has an internal groove just after the mating surface. I've seen one other clutch ring with such an internal groove, but never a lip on the mating surface.

Why are the two sides different? Should I smooth out the lip, or leave it alone - does it have a function?

Just finished a Parker 51 Vacumatic and looking at my clutch ring it is all equal all the way round so it would be interesting to know what you have there.

[grandmia]

Ahhh i've just enlarged the photos. It may be a clutch from a aerometric as they sometimes have a rubber O ring which will sit inside A. I don't think you will have a problem with side B as hopefully you will see that the barrel just below the thread has a step where the clutch ring will sit against the step therefore even if it did ( which I doubt it will ) dig into the lucite it is hidden with the clutch. IE The clutch sits on the step then the hood is screwed on against the clutch ring and nothing is visible.
Im not sure if that answer your question....Good luck with your pen.

[Flounder]

Thanks Stef.

I couldn't see enough of a gap in the barrel step to feel comfortable with that pesky sharp lip. I gave it some 12000 grit micromesh, and it smoothed out so quickly, I wonder if it could have been a slight manufacturing defect.

Anyhoo I'm happy it won't stress the barrel, and have reassembled the 51.

ps - that's interesting in re@ the O ring slot - I've seen that side A slope in other vac51s too. The whole business is a shoulder-shrugger.