Machined tool for Precious Plastic Brick

thingiverse

#Project intro: In early 2021 I decided that I was going to try to produce formwork (for poured structures such as concrete) out of [recycled plastic bricks](https://www.recyclerebuild.org/recycledbrick). This was in part because I'd heard that there's timber shortages, a crisis in plastic recycling, and I always wanted to figure out what to do with my waste 3D prints. In discussions with concreters and other builders who use formwork, I was told that the resulting surface finish of the structure was a very important consideration when selecting a material for formwork. This is why formply, with it's smooth exterior laminate is the industry standard, even if it rapidly becomes a waste product. This lead me to come up with higher specifications for tolerances & surface quality than the original, open source brick tooling designed by Precious Plastic. However I was determined that the geometry of their brick was still suitable for formwork, with the addition of a compression step, and more precise (machined rather than welded) parts. As a result I started work late last year in building a [PrintNC](https://threedesign.store/) specced to my project, with hardware that I am familiar with (Duet). This week, using steel I milled and cut on the PrintNC I was able to produce my first "early production brick"*. The mould's design is simple to replicate, costs less than $300aud, $200usd, 170gbp, etc. and can produce bricks without additional tooling, with nothing more than your body weight and some** heat. *that didn't break into pieces as I demoulded it. **understatement. #Project details: The current bill of materials for a steel mould is included as a text file. There is also an attached STL showing how the mould is assembled. Drill and tap where suggested by the CAD, and ensure the tool is tightly fitted together with no visible gaps before heating and putting plastic inside it. Draft drawings for a compression tool are included, for automatic compression and ejection of the brick. The compression tool & heaters I installed inside my mould can all be run on 3D printer hardware, using basic gcode. The Nema34 I'm including in the compression mould tool is best suited to an external stepper driver, with a higher voltage supply, however the tool could be redesigned to be driven by multiple, smaller motors and screws. A rudimentary list of materials required to make the mechanical ram: * 4x 1000mm 2020 extrusions * 6x 360mm 2020 extrusions * 2x 100mm 2040 extrusions * 20x 2020 corner brackets * 2x 40mm lengths of m5 threaded rod * ~100x m5 bolts & washers * 6x m5 nuts * ~100x m5 2020 tnuts * 20x open builds V-wheel * 20x alu v-wheel spacer * 8x M6x12mm if 2020 extrusions suit m6 thread * 2x nema17 motor mounts * 8x m3x8mm to mount nema17s * 2x 5mm shaft couplers for nema17s * 4x 3D printed components, in temp resistant material, high perimeter count, indicated in blue in the screenshot * SFU1605 ballscrew with nut * Flat, drilled pieces of steel to fit various components. Other heat resistant materials can be used. * 2x bearings OD24mm ID12mm H6mm * GT2 9mm continuous belt 440mm in length * 2x nema17 motors * 1x nema34 motor * Wiring, heatshrink etc. for connecting motors. #Automated compression tool steps: * Close pins at bottom of mould, locking heater block inside the mould. * Extrude required plastic into cavity at top of mould. * Push the ram down, closing the mould. * Wait for the mould to cool down (option to have active cooling) * Pull pins back one step, releasing heater block. * Drive the ram to push the heater block out. * Pull pins back all the way, releasing the rim of the bottom of the mould. * Drive the ram further to push the brick out of the tool.