Question aboot cap revolutions

[Fishbulb]

I don't have much experience with restoring pens yet, so excuse me if this is a dumb question.  Have noticed this with a few lever-filler pens now, but I'll take the one I was just fiddling with as an example.

 

# of revolutions just cap and barrel - 2.25

# of revolutions section, nib, and feed installed - 1

 

I'd though that it should be same # of revolutions, regardless.  So, is it that the section and inner cap meet after 1 revolution, and the rest of the threads are there for funsies?  I went as far as to push the nib and feed further into the section, in case the nib was poking the top of the cap, and got one revolution again.

[Bristol24]

Typically, the inner cap is placed in a position to prevent the nib from bottoming out inside the cap and being damaged. The section seals against the inner cap and stops the rotation, typically at one turn.

 

Cliff

[es9]

 

I have the one from Dr. Oldfield. I used to use two sticks, but I find the tool is nice. It would also be pretty easy to make one. 

 

 

[Bristol24]

31 minutes ago, es9 said:

 

I have the one from Dr. Oldfield. I used to use two sticks, but I find the tool is nice. It would also be pretty easy to make one. 

 

 

A very good resource.  I use my dial caliper's depth gauge and measure the depth to the top of the cap and then to the lip of the inner cap.  The difference is the measurement to avoid meeting or exceeding when setting the nib and feed in the section. 

 

Cliff

[dipper]

On 10/21/2022 at 9:57 AM, Fishbulb said:

So, is it that the section and inner cap meet after 1 revolution, and the rest of the threads are there for funsies? 

 

The extra turns of thread are there by design. Though (apparently) unused they ensure the screw threads engage smoothly without any possibility of jamming or damage caused by the taper where the threads terminate.

 

An example of the type of damage to be avoided can be seen if you have a steel bolt threaded over just half its length, and screw a nut onto the bolt all the way up to the end of the thread. If tightened further the nut will jam on the tapered shallower grooves where the bolt thread ends - distorting both threads, cutting  into the bolt, and making a mess of torn metal when unscrewed. Not pretty!

 

 

[Fishbulb]

Thanks, guys.  I whipped out my caliper and confirmed that there was no problem with any of the pens I was working on.  Special thanks to Dipper for the engineering perspective.