Screw Cap Proper Torque?

[Supernova]

I'm new to fountain pens and I did my best to use the fpn google to search for this, but I couldn't find much info. My questions is: When you are closing a screw cap, at what point do you stop screwing? From my limited experience, screw caps go on with no resistance for the first turn and a half, then you can feel the friction. In my mind, I should stop the second I feel any resistance because I don't want to wear out the threads, but on the other hand, it can back out and come uncapped if I don't tighten enough. Is there a rule of thumb or method that will ensure I'm tightening the correct amount? I don't want to wear out the threads or ruin a shirt. I'm probably over-thinking this, but I figured it can't hurt to ask.

[almoore]

Hi Supernova

 

In my limited experience different pens, with screw caps, require different numbers of rotations to remove/replace the cap so as a rule of thumb i gently replace the cap and rotate until it stops, I never take it last it's natural stopping point of apply any extra pressure. And, to date, I've had no problems.

 

Hope this helps

 

Al

[JotterAddict62]

Greetings and welcome to the fountain pen club...

 

Just snug up the cap..

[Bo Bo Olson]

Weak snug is fine...no need to crank it shut.

I learned that back in B&W TV days, when every kid was glad to get into 4th grade and finally use a fountain pen.

It will become second nature very rapidly.

As mentioned, some take more turns, others less, and also within the same company. One pen model may only take 1/2 a turn, another even of the same model might take 3/4's a turn.

Some other company a full turn, or even more.

 

You won't wear out the threads....unless you over tighten. I have vintage fountain pens that are over 50-70 years old, that work just fine...................don't know if the pens were used for all 70 years but can think they were used for 20-30 years at least.

[praxim]

Some have different thread pitches. Less force is needed on finer threads than on coarser, to make the cap snug.

 

Concentrate on how it feels when you undo the cap. Did it require a dash of effort before it broke friction to start unscrewing? Was it immediately loose? Your experience of undoing force is a good guide to whether you are using appropriate tightening force.

[catbert]

'Finger tight' - just enough friction/resistance to hold the cap closed by itself, not so much that you have to change your grip or move your whole hand or arm to crank it down (or subsequently to get it open again).

[Runnin_Ute]

Lots of good ideas. And as always YMMV- in other words every pen is different. One I have in hand at the moment - an Indian pen - Guider bought through a group buy. Tried it two different times sitting here - or two that I counted. One was six (yes 6) turns to snug. The second time was 8. (shorter turns. My Pelikan 140 - about 1.5. A Platinum 3776 about the same.

[pajaro]

You could easily overthink this. I think it's pretty simple -- finger tight. snug. Really torque it and you might crack something. With some pens, no matter what you do, the pen will sometimes work loose from the cap, but not all the time. It's easy to overthink things and over worry. Relax and just do the best that common sense indicates.

[two2tone]

0.367 newton meters.

 

I'm new to fountain pens and I did my best to use the fpn google to search for this, but I couldn't find much info. My questions is: When you are closing a screw cap, at what point do you stop screwing? From my limited experience, screw caps go on with no resistance for the first turn and a half, then you can feel the friction. In my mind, I should stop the second I feel any resistance because I don't want to wear out the threads, but on the other hand, it can back out and come uncapped if I don't tighten enough. Is there a rule of thumb or method that will ensure I'm tightening the correct amount? I don't want to wear out the threads or ruin a shirt. I'm probably over-thinking this, but I figured it can't hurt to ask.

[Supernova]

Some have different thread pitches. Less force is needed on finer threads than on coarser, to make the cap snug.

 

Concentrate on how it feels when you undo the cap. Did it require a dash of effort before it broke friction to start unscrewing? Was it immediately loose? Your experience of undoing force is a good guide to whether you are using appropriate tightening force.

 

I'm reading through this thread and your response has me curious. I do notice that if I tighten it super gentle, it unscrews effortlessly. If I go until it starts to get resistance and then give it the slightest touch more, it "sticks" and requires a slight bit force to get it to unsnug. Should it be unscrewing effortlessly or sticking a bit? In my mind, the sticking is by design to secure the cap and it's supposed to be that tight, but maybe I'm wrong.

[praxim]

 

I do notice that if I tighten it super gentle, it unscrews effortlessly. If I go until it starts to get resistance and then give it the slightest touch more, it "sticks" and requires a slight bit force to get it to unsnug. Should it be unscrewing effortlessly or sticking a bit? In my mind, the sticking is by design to secure the cap and it's supposed to be that tight, but maybe I'm wrong.

 

Sticking or not is partly a function of leverage as well as force. If you use the tips of a finger and thumb to tighten, then the same means to unscrew, it is possible to find a small sticking point. Now, tighten the same way to the same extent, then take the cap in the crook of your finger held by your thumb, and open it. I expect you will not notice any "stiction" because now you are using forearm muscles rather than your weaker but more sensitive hand muscles.

 

Generally speaking, I tighten with finger and thumb to a point which, from experience, holds, then unscrew with more speed or force (albeit still hand muscles not arm!). Some pens are not amenable to holding when they should. At least one starts to resist tightening before it is tight. That one has a lot of finely pitched threads. I tested several of my pens to make this reply.

 

As Pajaro commented, you can over-think this. If the pen keeps falling away from the cap or you crack the cap on your Waterman Patrician then yes, some adjustment may be needed.

 

I have not tested two2tone's specification because my smallest torque wrench's resolution is no better than 0.1 Nm.

[Tweel]

 

If I go until it starts to get resistance and then give it the slightest touch more, it "sticks" and requires a slight bit force to get it to unsnug.

 

That sounds just right.