Back in days of yore all plotters were tangential cutting toolheads. Instead of a blade tip being offset so that it can swivel as it makes a turn, the tool head is rotated by a motor and has no offset. It is theoretically the most accurate way to cut because the tip of the blade is always following the exact vector toolpath.
In actual practice, it is slower because the tool is lifted, turned and dropped back at every corner. Also an issue is some corners not being cut cleanly for reasons I won't go into. All Gerber plotters from the beginning in 1982 through the HS series were tangential. Tangential toolheads are also more expensive to build.
Early swivel blade systems were fairly unsophisticated adaptations used with plotters designed for pen drawings. They were inferior to tangential cutters and tainted the reputation of the technology. Today's swivel knife systems deliver exceptional accuracy and quality. They are faster, quieter and less expensive.
As an interesting piece of history, and having ordered a copy of Gerber's original patent on their vinyl cutting plotter, I can tell you that their original design used a hot tip to accomplish the cutting of vinyl. The first machine they actually brought to market though was a tangential cutting version.
The concept of the hot tip was later brought to market by a now defunct company named TechnoArts. They fitted what looked like a soldering gun to an Ioline plotter and did quite well for some time. It literally burned through the vinyl to accomplish cutting. They went out of business around 1990 or so, owing a lot of people money and ran their sign supply business after that known as Performance Sign Products. The manager of PSP, a nice young man, left them shortly after that and resurfaced as the owner of the old Airmark Sign Supply which went on to become Summa USA.
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