In order to facilitate cutting we purchased a Jobmate Dremel from Canadian Tire for approximately $15 CAD on sale.
We used a Dremel Flex Shaft to avoid the various issues that come with mounting the Dremel on the carriage. The snap brack that holds the flex shaft end pieces is discussed below.
We used a Dremel Tile Cutting bit for the vast majority of CNC Styrofoam cutting. The bit has decent length and cuts the Styrofoam well without melting it.
Adjustable Plunger End Stops
To make adjusting the end stops for the different axes easier, Guy Pommares designed adjustable sliding end stop plungers. The end stops were printed using the Makerbot Thing-O-Matic.
After printing the plungers, some sanding and cleanup were required for a nice fit.
Designed by Guy Pommares, printed using Makerbot Thing-O-Matic. The carriage follows a cam design to apply pressure and tightly hold the flex shaft in place.
The design is not just limited to the dremel flex shaft. Smaller objects, such as a pen or Styrofoam hot knife can be used with an adaptor.
Using a Dremel on Styrofoam (pretty much anything), produces a large number of particles, so we bought a $30 CAD shop vacuum from Canadian Tire for cleanup. We experimented heavily with mounting the vacuum cleaner tube on the carriage, but found that it resulted in significant resistance which affected cutting accuracy. Instead, cleaning is initiated after cutting has finished.
A must when using the Dremel to cut Styrofoam. The particles caused by cutting can irritate the lungs.
See the RAMPS post.
Putting it all together
The Dremel was mounted to the Mendel using two tie strips. The original plaster extruder head and carriage were removed and replaced with the Dremel carriage bracket.
To simplify wiring, a wooden board was added in which a kill switch, mechanical end stop wiring and the RAMPS board were mounted. This resulted in significantly cleaner wiring and a one stop location for all electronics.
Circuitry can easily become covered in charged Styrofoam particles from cutting. To address this a plexiglass enclosure can be situated around the RAMPS and other electronics. For us this ended up being a plastic food container that had the correct proportions.
The Y-axes end stop and plunger were moved closer to the electronics for the sake of wiring and to afford easier adjustment of the Y-axis end stop.
All STLs can be downloaded from here: