第六种：Elgin-Waineo machines
This is the most common type of machine at the moment, in industry as well as with amateurs, chiefly on the American continent. The main difference from the previous model lies in its single off-set arm (1) that oscillates around an axis (2) and is connected to a crank (4) and spindle (3) system which makes it work. This crank is of adjustable length. One famous variation about this design was proposed by an American amateur, optician Tom Waineo in the November 1995 issue of Sky and Telescope.
The major drawback of this machine is the limited variety of its movements due to the single eccentric sheave. Yet, some of its most experienced users manage to compensate for this handicap by frequently changing the machine settings. Of course this requires extreme dexterity. Among such users we find Carl Zambuto who has become an expert in the matter. | 
显身卡
