This page details a few of our initial experiments to use the 3Doodler and our CNC as a 3D printer and to see if the 3Doodler can be adopted as an extruder for a simple 3D printer.
Of course, it had to be opened up and we had to try and connect it to a CNC to make the first prints with this pen acting as a 3D printer's extruder ...
As features, the 3Doodler prints ABS and PLA plastic 3mm filament. There's a button to select material temperatures. Two buttons control two different speeds or reverse the filament (pressing both buttons) through a 0.4mm nozzle. There's a (rather noisy) fan to cool the cold end of the filament.
Interestingly, a few pins to connect wires to control the pen from external signals (a button, an Arduino, ...) are also available, but not yet documented.
You don't own something if you can't open it, so that was a first step. Here's a picture of some of its guts. These should be self-explanatory if you're into this kind of stuff.
You'll see a PTFE filament inlet, a driver to draw filament into the pen and a nozzle with an embedded heater and a thermistor to control the heat. The pen warms up amazingly fast and is ready to use in mere seconds!
One thing that got us pondering is that there are 2 motors controlling the flow of filament instead of a single motor. We're not sure about the design decisions that led to this design (single motor not strong enough?).
The other side just contains the PCB to control the pen. We couldn't identify the chip that is controlling the board (Nuvoton n79e813?), there is a 5 pin connector labeled "COM3" that may act as the PCB's programming interface.
The 3Doodler has 3 pins on the outside to which wires can be connected. This is, so far, an undocumented feature so we first tried to figure out what they do. Apparently, they're just pins that are connected to the two buttons for feeding the pen.
Simply wiring a pushbutton between Pin 1 and either Pin 2 or 3 allows you to control the pen from an external input. This could also be an Arduino or any other control board. It is important to note that there is a ~3 second delay between pressing either button and the extrusion starting.
A 3Doodler has all the features of an extruder for a 3D printer. It warms up extremely fast, and you can control the extrusion through the breakout pins on the pen. Provided that the board can be further circumvented and reprogrammed, different extrusion speeds than the default one should be possible.
So, let's connect it to a CNC!
We used a few cable ties to connect it to our CNC's spindle mount and routed a button to an external button so we can easily control it.
After a bit of calibration, we fired up pronterface, connected to the CNC machine (the CNC runs a version of Sprinter) and quickly we had our first print using the 3Doodler!
So here you have it, as far as we know, this is the first (2D) print made by a CNC whose extruder is nothing more than a 3Doodler!
We paused a bit between G-code movements, which caused these blobs. We'll need to have a look at the delay between activating the extruder and the actual printing of material (some 3 seconds).
Still, converting a CNC into a 3D printer with the 3Doodler now seems like a quick (<30 minutes) and cheap (99$ for a complete extruder with some quality components!!!) hack, if you already have a CNC, of course. We were quite impressed with the initial quality of the extruder.
One comment that was made is that the 3Doodler sports DC motors which are not very suitable to be used as a power source for the feed of filament as they lack precision in comparison with steppers. We are however happy with the consistency of speed of extrusion, it's not as bad as we presumed before doing these experiments.
It should be fairly easy to write up some special firmware to control the extruder at variable speeds so we can actually print more than just a two dimensional square ... But as a proof of concept, this is all very promising!