Crash and burn?
When the script file is generated a number of parameters can be specified, one of which is Infill - The model is not solid - the software constructs braces within it to give it strength. The more infill you have the stronger the model but this requires more material and takes longer to print.
Greplicator model parameters
Printing is a slow process, so rather than connecting the Makerbot to a computer and risking a crash or reboot, instead, we saved the script to an SD card and plugged it straight into the Makerbot. The Replicator’s plywood chassis contains three sets of stepper motors, two of which control the X and Y axis of the print heads, which in the world of 3D printing are called Extruders. The third raises and lowers the platform to give the model height.
The platform has to be level and setting it up is pretty low-tech. The platform needs to be covered with a film, (called Kapton) which needs to be applied bubble-free. The extruders are then moved to various points around the platform with a piece of paper held between the extruders and the film.
You slide the paper to make sure there is just a little grip. If there’s too much you turn a screw to lower that part of the platform, no grip at all and you raise it. Since this is a machine that chugs around and gets hot and cold it’s definitely not a set-and-forget process.
The hot and cold bit is extremely important. Melting plastic needs something very hot and there is a lot of metal to heat in the extruders and platform. The extruders run at around 220°C and the platform has a default temperature of 100°C. The “Burn, crush and Cut Hazard” warning labels on the front of the device aren’t just there for show. Heating to takes a little over 10 minutes – which should make you a little less impatient the next time you’re tapping your feet waiting half a minute for your shopping list to be spat out of the laser printer.
A raft of possibilities
The first stage of the printing process is laying down a raft. This is a mesh which grips the Kapton and provides some plastic for the model to be built upon. It’s mostly necessary for models which don’t have a flat-ish bottom and might not have been necessary for our Vulture head.