Perforation Hole Position Parallelism

There is something that has been disturbing me for some time about what appears to be so called matching parallelism between the perforation holes found on the opposite rows of vertical perforations and on the opposite rows of horizontal perforations. This is to be expected from stamps that have been perforated by rotating bars mostly and sometimes but rarely and coincidentally on stamps perforated by rotating wheels.


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perforation hole matching parallelism (perforating bars)


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perforation hole non-matching parallelism (perforating wheels)


Flat plate perforation 11 (Kiusalas 72 = 10.94) should tend to show non-matching parallelism because it was made by rotary perforating wheels. However, unless I am mistaken in most of my observations of U.S. Scott # 596 and # 613, they tend to show matching parallelism on their perforations which is not to be expected for such perforations made from perforating wheels. See

https://siegelauctions.com/display_...hp?catno=596
https://siegelauctions.com/display_...hp?catno=613

The perf pins are on a freewheeling rotating wheel. Perfs will mostly not line up but it can happen, it's not impossible. The #596 in color on the pages above was probably selected for "balance", with full corner perf teeth. The perfs may look matched by eyeball but put a square or architect's triangle on the image and there are tiny differences. Look at all the other photos on those pages; they don't match up from what I see. Look at the #613 pair; cover up the top horiz perf between the stamps and by eyeball, the top and bottom perfs look matched. Looking at the bottom center perfs only, someone could even think #613 was a comb perf stamp. Uncover that one horiz perf and I think you can see the difference.

I noticed this some time ago, and it was explained to me that the rotary stamp designs, being a bit taller in this case, required adjusting the perforating equipment to the required spacing. Typically, the machinist aligned the perforations each time he did an adjustment. The alignment didn't last very long, so only the stamps with short runs like the tall rotary sheet wastes and #461 typically display this alignment.

Tipzi: Thanks. This makes sense especially if the known examples all come from the same pane such as only from one (or two) of the first perforated panes after the adjustment. Since there are more copies of U.S. Scott # 594, some show perforation hole matching parallelism and others show perforation hole non-matching parallelism depending on the horizontal or vertical sides. See: https://siegelauctions.com/display_...s.php?id=235