The latest Stamp Insider mentions that Unique Binders (part of SSP USA) uses conical pins that raise bumps in the paper before shaving them off (using blades similar to those used in lawnmowers) to create perforations. When the pins wear they are ground down, resulting in larger perforation holes.
Does any reader know (a) who makes this type of perforator and (b) what name it goes by?
I can briefly summarise a method developed in the UK/Sweden, as follows.... "A stand-alone reel printed rotary perforating method was developed in the early 1960s by a Swedish engineer for Harrison & Sons. Made by APS (AB Produktions Service) of Sweden.
Also known as the 'lawnmower' type because it shaves off raised pimples (located on the pin tool cylinder) with 'burr' blades (on the cutting cylinder), creating holes by abrasion instead of by punching out holes."
The UK/Sweden version has pimples and not conical pins, so we do not experience the need to grind down and therefore manage to maintain the same sized holes through print runs of a stamp.