Are 1.0 pitch threads too course for section making?
- Thread starter TonyL
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monophoto
Member
Tony
The problem is not the pitch of the thread. I have commercial pens that have threads with a 1mm (or even greater) pitch - that's not a problem because the threads aren't standard threads.
The problem is that you will be using standard metric taps and dies to create standard metric threads. The ISO standard for metric threads specifies as the dimension in mm from the centerline of one thread to the centerline of the adjacent thread. Also, that standard specifies that threads are an equilateral triangle with the tips of the peaks, and the bottoms of the valleys flattened, and that the ratio of the height of the thread (measured from the flat bottom of the valley to the flat top of the peak) to the pitch is a fixed number (which happens to be 0.541).
So with standard metric threads, as the pitch increases (ie, the number gets larger which means that the spacing between threads increases, the depth of the threads also increase. In other words, as you increase the pitch of the threads, you must allow for the increased thread depth by having thicker material. Or conversely, if you opt for a finer thread pitch (ie, a smaller number), you can plan to have the walls of the body thinner.
So ultimately, the issue is how thick do you want the barrel wall to be?
Metric threads are confusing to those of us old guys who grew up with imperial dimensions where pitch is defined as the number of threads per unit of length. In the imperial world, increasing the pitch number means that the threads are finer; in the metric world, it's exactly the opposite.
The problem is not the pitch of the thread. I have commercial pens that have threads with a 1mm (or even greater) pitch - that's not a problem because the threads aren't standard threads.
The problem is that you will be using standard metric taps and dies to create standard metric threads. The ISO standard for metric threads specifies as the dimension in mm from the centerline of one thread to the centerline of the adjacent thread. Also, that standard specifies that threads are an equilateral triangle with the tips of the peaks, and the bottoms of the valleys flattened, and that the ratio of the height of the thread (measured from the flat bottom of the valley to the flat top of the peak) to the pitch is a fixed number (which happens to be 0.541).
So with standard metric threads, as the pitch increases (ie, the number gets larger which means that the spacing between threads increases, the depth of the threads also increase. In other words, as you increase the pitch of the threads, you must allow for the increased thread depth by having thicker material. Or conversely, if you opt for a finer thread pitch (ie, a smaller number), you can plan to have the walls of the body thinner.
So ultimately, the issue is how thick do you want the barrel wall to be?
Metric threads are confusing to those of us old guys who grew up with imperial dimensions where pitch is defined as the number of threads per unit of length. In the imperial world, increasing the pitch number means that the threads are finer; in the metric world, it's exactly the opposite.
I use m10x1 all the time. Originally copied from the Churchill or ElGrande kits which use that thread. Before I made sections, they were the ones I used as replacements were readily available.
I am lost, but that is ok! That just means mean that I have a lot more to learn. I was just getting some of the terminology today (roots and crests, min and max diams, etc,).
Thank you both!
Carl Fisher
Member
M10x1 is one of the more common threads in custom pen making for section to body threads. The short version of what monophoto was trying to say is that the higher pitch number will result in a deeper thread so just watch your wall thickness.
Thank you.