PrototypePrinter

The prototype printer is constructed largely from Meccano and Polymorph. Test articles have been made on the Stratasys FDM printer that show Meccano components can be readily replicated, but for the moment there is no pressing need to use anything other than Meccano.

The device is constructed on a sturdy wooden base, which holds the mechanism clear of the ground and prevents vibrations during use. A carriage moves left-right along a 500mm length of M5 studding, powered by a stepper motor. The carriage carries a 150mm diameter turntable, which is raised and lowered by another stepper motor via a 3:1 reduction gearing. This motor drives a piece of M4 studding held in a captive bolt in the carriage body. As the studding rotates, the turntable assembly goes up or down. Eventually, 3 pieces of studding will be used for stability. Stability is currently provided by 3 vertically sliding rods.

The turntable is rotated by another stepper motor via a 57:1 worm gear. An index to its rotation is provided by a simple magnetic reed switch, as found in burglar alarms. The turntable has 3 adjustment screws to level it, and 3 more to level the rotating gear.

A sturdy welded metal frame constructed from 25mmx50mm steel box section with top rails 100mm apart provides a gantry for suspending extrusion heads from. Currently, a simple EVA "hot-melt glue" extruder driven by a DVD tray motor is used to provide extruded plastic, though this will be replaced with a Polymorph head.

Many heads may be placed on the gantry, and provided that each is lined up with the centre of the turntable the mechanism can position any point on the turntable underneath any head on the gantry.

The design is particularly suitable for the construction of rotationally symetrical parts such as gears, and has secondary uses such as winding coils.

-- Main.VikOlliver - 12 Oct 2005