I produced the following as part of a leaflet I give to customers. It might help those who are a little unclear as to the 'whats and whys' of multi-start threading:
What is a Multi-Start Thread?
When you screw the cap onto your precious new fountain pen or rollerball pen, it helps to be aware that it uses a multi-start thread. A single-start thread, as seen in the diagram below left, can only screw on one way and takes six full rotations to fully close. A multi-start thread, as illustrated below right, actually has a number of different parallel threads running alongside one another, which drastically reduces the number of rotations it takes to fully close.
In the illustration a two-start thread halves the number of turns required, from six to three.
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Most fountain pens have three-start or four-start threads to make it easier to screw on the cap.
Why Do I Need to Know This?
Because multi-start threads actually consist of a number of separate threads running parallel to one another, your cap can screw onto the barrel of your pen in a number of different orientations. We as pen-makers work very hard to present our pens as perfectly as possible, so we have chosen one start which best matches the patterns between the cap and barrel, or which best shows off the natural grain of the timber used.
While there is nothing wrong with screwing your cap on using any of the starts, you may end up with the effect shown in the second diagram below, where the patterns or the grain don't match up.
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If you wish to ensure that your pen is always perfectly presented when capped, this can be easily accomplished. If you screw the cap on and the patterns or grains don't align, simply unscrew the cap while maintaining slight closing pressure on it. As it reaches the end of the threads it will 'click' over to the next start. (You will more likely feel than hear the click!) Screw it down again and observe the pattern or grain. If it is still not perfect, repeat the process. You may have to do it as many as four times depending on the number of starts in your particular cap thread.
