# 3 start cap turns to close



## JLL (May 24, 2016)

What's the general consensus on 3 start cap turns to close 3/4 -1 - 2 - 3 ?


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## bmachin (May 25, 2016)

Don't know if you will find a consensus, but here is some data on some factory pens from my collection:

A german pen (don't remember the brand), machined rather than molded, quad start, 1 1/4 turns to close.

A modern Pelikan, injection molded:  quad start, 1 turn to close.

A 30 year old Montblanc 149, injection molded:  quad start, 1 turn to close.

A Gate City Belmont, machined:   triple start, 2 1/2 turns to close.

1939 Parker Vacumatic, threads seriously worn, machined:  triple start, about 1/4 turn to close.  

FWIW,  don't obsess over getting the number of turns exact, but shoot for a minimum of 1 and less than 2.

Hope this helps.

Bill


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## Carl Fisher (May 25, 2016)

Anything over 2 and people start to notice it. Anything between about 1 1/4 and 2 seems to be about right.

Less than 1 and people notice as well. Ideally you want it so they don't even think about it.


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## Takari (May 30, 2016)

Interesting.  The single starts that I make average 1.5 turns.  I was under the impression that multi-starts were running 1 turn or less (the two that I own are 1.0 and 0.75 turns).

My single threads are strong and stay closed well.  They do require some precise machining on my part but other than that I don't understand why I would switch to multi-threading.  Am I missing something?  Will the singles strip as time goes on?  It's true that they only grab onto a few threads.


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## bmachin (May 30, 2016)

I agree with Carl.  On my 2 1/2 turn Gate City it seems like forever to open and close. 

I seem to remember threads on this from a few years back.  The main "engineering" reason as I recall was that a single start thread offers more mechanical advantage than a multi-start thus making it easier to strip for a given amount of torque.

On the other hand, Multi start threads are much steeper which might make it easier for a cap to come loose in a shirt pocket (DAMHIK). On the other hand, multi-starts have more thread contact area and thus more friction for a given number of turns.  I'm not smart enough to do the calculations.

One final thought.  If, for example, you have a pen requiring 1 1/2 turns from thread engagement to closed, it could take up to 2 1/2 turns to close with a single start but only 1 5/6 turns with a triple start.

For what it's worth, and in this case probably very little.

Bill


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## pencap51 (Oct 27, 2016)

Hi all, I am a new member.

I have a probably basic question that is relevant to this thread:

Do dies differ as far as single vs multiple starts is concerned?

In other words, if I want to create a multiple start thread, do I need to look for a die with a specific designation that is different than the ones that produce single start threads?


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## More4dan (Oct 27, 2016)

pencap51 said:


> Hi all, I am a new member.
> 
> I have a probably basic question that is relevant to this thread:
> 
> ...



The dies are different. A triple die cut 3 parallel threads at the same time a 120 degrees offset from each other. Think 3 spirals running beside each other. 

Danny


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## magpens (Oct 28, 2016)

Hi, Will, and Welcome to IAP !!!! . You should introduce yourself in the Introductions Forum ... you could win a prize !!!! :biggrin:

To answer your question ... Yes, non-single start taps and dies do bear a characteristic designation.  For example, a triple start tap will have the number 3 after the diameter and pitch designation ... like 12x.75x3 etched on it for a 12mm with a .75mm pitch triple start.

And where are you planning to look for these kinds of animals ? . Here is the most likely place, I would think; here, in the possession of penturners.

BTW, it's about time that one of our members is due to start a thread for doing a group order for a multi-start tap and die. . Keep watching the New Posts.

But I think this is not quite the subject intended by the OP of this thread (OP = Original Poster, or Starter).


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## pencap51 (Oct 28, 2016)

More4dan said:


> pencap51 said:
> 
> 
> > Hi all, I am a new member.
> ...



That makes a lot of sense. Thank you!


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## pencap51 (Oct 28, 2016)

magpens said:


> Hi, Will, and Welcome to IAP !!!! . You should introduce yourself in the Introductions Forum ... you could win a prize !!!! :biggrin:
> 
> To answer your question ... Yes, non-single start taps and dies do bear a characteristic designation.  For example, a triple start tap will have the number 3 after the diameter and pitch designation ... like 12x.75x3 etched on it for a 12mm with a .75mm pitch triple start.
> 
> ...



Thank you so much for the info and the warm welcome. Technically I have not yet started my pen turning journey, so I'll be quiet and ask questions for now 

I'm sorry if I asked this in the wrong thread.

And I'll be interested in a group buy because I know I'd be creating threads for the pens I have planned to make.


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