Folding Flaps and Conveyor Belts

The Meccano prototype used a centre roller to drive the paper through the folding area, but this turned out not to work well in the full size version. A pair of conveyor belts is now being used instead.

The unfolded paper is driven between the conveyors and a pair of metal rails, where it stops. Flaps fold the paper up around the rails, motion is restarted, and the folded paper is driven off the end of the rails into the creasing rollers.

The flap mechanisms and rails can be slid sideways to adjust the distance between the folds and thus accommodate different widths of paper. The adjustment process is somewhat tedious at present; this is a possible area for future improvement.

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An early stage of construction before the folding rails were added. Sprung pads under the belts (one visible here) were used initially in an attempt to improve the grip of the belts, but have since been removed, because they resulted in too much friction between the paper and the rails.
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Another early view showing one flap mechanism with the flap raised. The grey metal platform was later replaced with the narrow rails shown below, to reduce friction.

Recent view, including folding rails. The rails are painted and polished to minimise friction. Side panels have been added to support the paper before folding.

Folding flaps in the raised position.

A phototransistor detects when the paper has reached the correct position for folding, and when it has passed through the creasing rollers after folding.