The Evolution of
Meccanographs
by John Ince
On the inside back cover of the April 1971 Meccano Magazine there was an illustration of a new automatic Meccanograph. It was described as follows:
From Holland - the Meccano Designing Machine - a surprise a minute!
This is a machine that never ceases to surprise and attract attention! Original and ingenious in its use of Meccano pieces, it employs most types of gear combinations to produce drawings at the rate of about one figure a minute. No two drawings are ever the same-and it's impossible to tell in advance what the next design will be like. At the end of each drawing the pen is automatically raised and the paper moved along to present a clean space for the next design. The pen is driven by two linkages, which in turn are driven by a crank from a separate gear-set. As each gear-set rotates a new reduction ratio is introduced between the main shafts and the cranks that drive the linkages. During the course of producing a single design, each gear-set moves through one complete position. As one gear-set has five positions and the other six, this means that in theory only thirty different designs would be drawn before the same combination of gears started again. But in practice this never happens because in the time between the designs the phase relationship of the two cranks that drive the pen linkages changes, and a special mechanism changes the amplitude of their motion. So in fact all the designs drawn by the machines are different, and it is impossible to tell in advance what they will be like, Beat that for originality!
As far as I am aware the details of that machine were not published. Evidently the concepts attracted interest in New Zealand as, by 1980, a Christchurch Meccanoman, Jack Locker, had produced his own version and demonstrated it at the Easter Convention of that year. I did not see it then but it worked beautifully until running out of paper. I did see the machine in 1989 and took some photographs. From these I attempted to reproduce the model but was not successful.
The two cam concept is a great idea and I was able to incorporate it into my Mk II Meccanograph described in Model Plan 138. This machine made use of another useful device, the Schmidt coupling. Now I have completed the design of two more Meccanographs, both of which use another borrowed idea, variable table rotation speed. This was demonstrated in the Konkoly Magnificent Meccanograph which was described in the August 1965 Meccano Magazine.
The new designs are soon to be published in Model Plan 147. These two Meccanographs, Mk III and Mk IV, are a development of the two described in MP 138. Both are designed to produce patterns with up to fourteen peaks or sides. This is achieved by gearing the table rotation and the table reciprocal motion so that the one relates to the other by the factors two to seven. Once again the Schmidt coupling provides the means of driving the table rotation in the situation where the table is moving to and fro laterally.
Either Meccanograph may be constructed with a No 10 Set with a few extra parts and both are quite compact. Mk IV, which is the larger, will easily fit inside a 15" cube.
In summary, these Meccanographs have borrowed the Schmidt coupling, the variable table rotation speed and, in the more complex version, the double cam pen drive to produce interesting and adaptable models. The beauty of the double cam is that it allows phase changes which vastly extends the variety of patterns.
I prefer to stay with hand operation as this makes the machines especially popular at exhibitions where the young people may produce their own patterns to take away.
(Author’s note March 04: Two readers have pointed out that the Dutch Meccanograph was in fact described in the Constructor Quarterly Nos 2 and 3.)
