Why Do Some Parker 51 Nibs Have A Partial Nib Slit?

[joss]

A few months ago, there was a question here on a Parker 51 pen with ink flow problems, which was suggested to result from a nib that did not have a 'full length' slit.

 

The 'partial slit' nibs are found quite regularly on the Parker 51: instead of ending in the breather hole, the slit ends in a circular imprint that is located about 0.0787 inch (2 mm) below the breather hole. It looks like this:

 

I did not find an explanation on why these nibs were made like this. Was it to produce a stiffer (less flexible) nib that could be used for instance for carbon paper copying?

Edited January 3, 2012 by joris

[joss]

Mmmm ... I thought that my question was an easy one for all you Parker 51 aficionado's out there.

But it appears it isn't :hmm1:

[richardandtracy]

I was hoping someone else would answer.. :embarrassed_smile:

 

OK. Here goes.

 

The nib slit on the P51 only needs to be short to get it over the feed slit. It often ends in a hole (see top nib in photo here: https://www.fountainpennetwork.com/forum/index.php?showtopic=62073&st=1 )

 

Now, the hole is only needed as a crack stopper and blunts the 'crack' that is the nib slit. However, there is another way of doing it. You stamp a ring in the nib to compress the metal & set up a compressive stress field in the area. If a crack grows from the end of the slit to the ring, it stops because it cracks only grow when there is tensile stress in the metal - which is overwhelmed by the static compressive pre-stress stamped into the metal.

 

Regards,

 

Richard.

[joss]

Richard, thank you for taking the time to answer my question on the partial nib slit.

 

I do understand the need to have a hole or a stamped ring as a crack stopper / stress reliever and I also understand that there is no need to have a long slit. But I wonder why these nibs do have a hole and the stamped ring. It can be assumed that all P51 nibs were manufactured standard with the hole but there must be a reason why the slit in some nibs was not cut up to the hole, necessitating an extra stamping of a stress relieving ring. It is not likely that Parker put extra time (and thus extra money) in the nib manufacturing process if there was not a reason for this short slit.

 

That is why I thought that the shorter slit would produce a more rigid (eg manifold) nib. I saw a more or less similar thing on 1950s Pelikan nibs: their Manifold nibs have a second hole that is placed halfway of the regular hole and the nib slit runs only up to the first hole (a picture can be found here, see 'Manifold nib')

 

So actually my question is whether the partially slitted P51 nibs can be called Manifold nibs or is that nonsense?

Edited January 9, 2012 by joris

[richardandtracy]

I think the bigger second hole was for a Parker nib removal tool. I think the tool slipped up under the hood and hooked into the bigger second hole, and allowed the repairer to pull the nib out without removing the hood. If I remember rightly, a couple of years ago either RonZ or Richard Binder suggested that this tool can damage the hoods and/or collectors, so the idea isn't used much these days.

 

One thing: the P51 nib is really a manifold nib anyway, isn't it? It's certainly suitable for use on Carbon papers.

 

Regards,

 

Richard.

[Tom Heath]

Thought you all might like to see one such Parker Nib removal tool

 

Tom

[richardandtracy]

Thanks Tom, glad I wasn't dreaming.

 

Regards,

 

Richard.