Repstrap V2

It is fun to see how deprivation of material can spark creativity! By setting the boundaries for this project to use ONLY the parts of printers and computer junk, you can – will come up with solutions you otherwise wouldn’t have thought of!

After last week’s enthusiastic post, reality kicked in hard when trying to control the steppermotors. Bottom line: they were by far not strong enough to power the metal carriage (normally they only have to move a plastic printer head) Besides lack of strength, they also lacked resolution. With one step (motor 7.2 degrees) more than one milimeter is covered! This makes it hard to get enough precision for printing parts.

One other problem is synchrony between the two side-axes. The slightest difference between the two motors causes the system to jam. The only way to prevent this is to mechanically link both motors.

It came as a surprise that it is possible to do all this using only the remaining parts of the matrix printers. The gears that were previously used for driving the paper roll have been used for a reduction in the drive train. Superfluous gears normally used for spinning the ink-lint have been used as bearings.

The last two pictures show two optical detectors as end-stops for initialization purposes.

Between the two halve shafts that couple the motions from both Y axes, a temporary meccano solution has been made as flexible shaft coupling. Eventually something will have to be distilled from the printer parts, or I will cheat with an ordered flex coupling.