Twists And Turns

[vicpen123]

I have noticed that the number of twists and turns required to securely fasten a barrel to a section varies for different pens. For example (to the nearest quarter turn and measured by aligning the clip with the nib and twisting) this is what I have observed and recorded from my modest pen collection:

 

Parker "51"x 1.5 twist and turns

Parker 45 x 5

Parker 75 x 4.5

Parker Sonnet x 7.5

Parker Duofold Centennial x 7

Parker Premier x 5

Italix Parsons Essential x 3.5

Sheaffer Imperial 11 x 4

Sheaffer No Nonsense x 6

Sheaffer Triumph Imperial x 2.5

Danitrio Cum Laude x 6

Pilot Metropolitan x 3

Pilot VP x 2

Platinum 3776 x 3

Sailor 1911 M x 8

 

If 1.5 turns is enough to secure a P "51" then why do other pens require more? Is it a function of the material used for the pen, the threads, previous misadventures for certain pen manufacturers, a design feature, a manufacturing requirement or just for fun to confound pen users?

 

Please comment and add to our collective knowledge.

 

 

[FarmBoy]

I suspect if you consider thread pitch, number of leads, and threaded length the numbers will be more clustered if you express the result in radians.

[basterma]

I think some of the materials are more brittle or susceptible to cracking near threads. Those materials will get a much more coarse threading than others. Aluminum and softer metals will need a different threading as well to prevent bending of the barrel when in pocket. I noticed that some combinations of material and threading will wobble more than others, so that also may be a concern.

[FarmBoy]

I think some of the materials are more brittle or susceptible to cracking near threads. Those materials will get a much more coarse threading than others. Aluminum and softer metals will need a different threading as well to prevent bending of the barrel when in pocket. I noticed that some combinations of material and threading will wobble more than others, so that also may be a concern.

Wobble in threaded connections is typically an indication of quality.