RepStrapOko

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3D printers have the idea of being able to bootstrap, either by using one printer to print the parts for another printer (doubling) or using another machine to otherwise bootstrap the process. There is a page on the reprap wiki for a MillStrap, but it's incomplete.

One can adapt a Shapeoko to 3D Printing, either as an occasional, alternate "spindle", or to use to bootstrap the manufacture of a 3D printer.

Creating a RepStrapOko is at once straight-forward and complex. In theory, one would simply bolt on an extruder and begin printing. In practice, one needs the heart of a 3D printer, and a transplanted control system.

  • Extruder/Cold End --- Greg's Wade reloaded works well, one need merely add properly spaced holes to the back plate to allow for mounting.
  • Extruder/Hot End --- ostensibly part of the extruder, is normally sold separately. Needs to be selected for the final diameter and the diameter of filament which it accepts. Includes a thermistor to heat up the element, and a temperature sensor to determine the temperature.
  • Stepper Motor --- the Extruder will need its own stepper motor and the control board will need to have stepper driver for it. Amazon

It will also be necessary to mount it in such a way that the balance of the machine doesn't get in the way. One option for this is to use the universal spindle mount, machine a 160mm x 80mm plate w/ suitable screw locations and use long bolts w/ spacers to attach the extruder so that it reaches down to the print bed, projecting below the gantry so that the gantry doesn't interfere w/ the print.

  • Extruder Mount Extender Plate --- 160 x 80mm HDPE or other suitable material[1]: http://www.shapeoko.com/forum/download/file.php?id=3599 (unfortunately a standard carriage plate won't quite fit)
  • Mounting Hardware --- 4 x long M5 bolts, spacers, 4 short M5 bolts, 8 M5 nuts, 16 M5 washers --- it may be possible to design the above to allow the use of M5 insertion nuts which would simplify the assembly and allow one to forgo using a wrench.

In addition, it will be necessary to source a more powerful power supply --- add up the Amperage of the motors (don't forget the extruder), hot-end (also heated bed if going that route) and fans and get one comfortably more powerful than that.

  • 24 volt power supply --- amperage must be appropriate to the sourced motors, hot end and fan(s). With careful tuning a 5Amp unit may be made to work, but 10 Amps would provide more headroom.

An Arduino / gShield only has 3 stepper drivers, and no support for a hot end. Rather than source a new shield it is more straightforward to simply use a new, all-in-one micro-controller:

One would also need all the attendant support materials / electronics:

  • Kapton tape --- used for assembling the hot end and insulating wires
  • fan(s) for cooling
  • High Temperature Wire (it may be possible to forgo this if one has suitable heat sinks in-between the hot end and other wires)

And a surface on which to print. Options include:

Naturally one will need filament to print with ---

  • Filament
    • PLA --- get a light-coloured, easily marked material to begin w/ to allow for easier measurement
    • ABS --- pretty much requires a heated bed, also ventilation becomes a concern

The spool of filament will require a holder which will allow dispensing. This is easily made w/ Lego bricks and a 1" dowel for a first usage of the machine --- a long-term solution can then be printed.

References