3 start cap turns to close
- Thread starter JLL
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bmachin
Member
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
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
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.
Less than 1 and people notice as well. Ideally you want it so they don't even think about it.
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.
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.
bmachin
Member
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
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
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?
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?
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
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).
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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That makes a lot of sense. Thank you!
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.