Designed by Andreas Konkoly and described in November 1972 issue of Meccano Magazine.
This was a model I was fascinated with in my youth and is still probably the favourite amongst the models I have constructed. I had to cut a lot of lawns and wash a lot of cars to save up for all the required parts the first time I built this.
I have built this model in several forms over the years, including for a SELMEC Secretary’s Challenge using only part numbers in the range 1–50 which necessitated a degree of ingenuity!
For this current version I have used a sturdy box frame but kept the mechanism layout essentially as per the original.
This version employs 30DP gears of Tony Bolton origin almost throughout and allows designs of 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16 and 20 ‘lobes’. Four options of line density and four settings for table travel sensitivity are also available. The axis of the arm can also be offset in this version, and using Stuart Borril control discs, many more variations to table movement are possible.
After much experimentation to control the table backlash, a simple friction arm at the edge of the table disc has been incorporated which is the equivalent of Konkoly’s method of applying light friction of the operator’s finger. Careful alignment of the bearing plates is critical so these are all carried on straight non-Meccano rods secured with collars. A future version is planned which should include the ‘missing’ ratios 7, 11, 13, 17, 18 and 19 which cannot be obtained with the current two-stage gear pairs I have selected in this version.