Bringing personal fabrication to your kitchen: the pizza Plotter. During one of the last lectures I gave for Creative Technology about reprap’s and personal fabrication one of the pizza hungry students (Symplexity) pointed out the necessary connection between pizza and production. Thus the idea for a Pizza Printer was born.
The previous posts on the Repstrap describe a 3D carthesian robot made from dot Matrix printer parts (using ONLY parts from three StarLC10 printers). Instead of the Z-axis the nozzle of a pressure plant mister was put on the head. The tank has been filled with tomato sauce. See the results on youtube below:
OK. admittedly, the accuracy needs some work. This has more to do with pressure / extrusion control than with the 2D robot. (which is basically an ordinary ottantotto controlled plotter now). The original StarLC10 power supply has been used, along with part of the casing. A standard RC servo has been added to the plant mister nozzle, allowing for on-off control for move- and draw commands. The ottantotto controls three stepper motors directly (using four wires per motor). The original stepper driver chips (STA401A) have been salvaged and re-used. For all the motors a single STA401 has been used. The control signals of both parallel motors have been bridged.
A drawing is made using a very simple processing sketch, based on the ‘file-save’ examples.
/**
* sketchtool, based on the 'filesave' example.
* move mouse. Every time you click, a datapoint will be saved
*/
int[] x = new int[0];
int[] y = new int[0];
void setup()
{
size(512, 512);
frameRate(30);
}
void draw()
{
background(204);
stroke(0);
noFill();
beginShape();
for (int i = 0; i < x.length; i++) {
vertex(x[i], y[i]);
}
endShape();
// Show the next segment to be added
if (x.length >= 1) {
stroke(255);
line(mouseX, mouseY, x[x.length-1], y[x.length-1]);
}
}
void mousePressed() { // Click to add a line segment
x = append(x, mouseX);
y = append(y, mouseY);
}
void keyPressed() { // Press a key to save the data
String[] lines = new String[x.length];
for (int i = 0; i < x.length; i++) {
lines[i] = x[i]*4 + "\t" + y[i]*4;
}
saveStrings("positions.txt", lines);
exit(); // Stop the program
}
Tomato Sauce and Pressure Vats are a match made in white-wall hell. At least until I fully understood the merits of hose-clamps. Luckily, if you are quick enough, the stains wash off well.
The printing program is equally simple (but will follow in a next post) The Ottantotto software has been made using winavr (since it involves timer interrupts, and I really love the AVRlib libraries from procryon)
It is fun to see how deprivation of material can spark creativity! By setting the boundaries for this project to use ONLY the parts of printers and computer junk, you can - will come up with solutions you otherwise wouldn’t have thought of!
After last week’s enthusiastic post, reality kicked in hard when trying to control the steppermotors. Bottom line: they were by far not strong enough to power the metal carriage (normally they only have to move a plastic printer head) Besides lack of strength, they also lacked resolution. With one step (motor 7.2 degrees) more than one milimeter is covered! This makes it hard to get enough precision for printing parts.
One other problem is synchrony between the two side-axes. The slightest difference between the two motors causes the system to jam. The only way to prevent this is to mechanically link both motors.
It came as a surprise that it is possible to do all this using only the remaining parts of the matrix printers. The gears that were previously used for driving the paper roll have been used for a reduction in the drive train. Superfluous gears normally used for spinning the ink-lint have been used as bearings.
The last two pictures show two optical detectors as end-stops for initialization purposes.
Between the two halve shafts that couple the motions from both Y axes, a temporary meccano solution has been made as flexible shaft coupling. Eventually something will have to be distilled from the printer parts, or I will cheat with an ordered flex coupling.
Some time ago I tried rep-strapping using 5-1/4” diskdrive motors and MDF wood. (see here). The motors turned out to be way too weak, the M5 thread way to slow. Perhaps a larger thread (M12) and some bigger steppermotors can save this evening of work.
In this second attempt I have been using only the parts of three old dot-matrix printers (star LC10) and other computer parts. (I cheated a little bit. So far the extra parts include a big slab of MDF wood and two M8 bolts with washers and nuts)
So far I have build a 3D cartesian robot using the three printers. For the Z-axis I have added the mechanism of a CD-ROM player. Next part will be the motor control (also using the salvaged motor control hardware from the original printers) and an extrusion head (probably not completely from printer- or discarded computer-junk parts)
I’m not particularly clumsy. Ehm.. That is to say.. I’m not particularly clumsy when it is not Early In The Morning, when I have consumed to much drinks containing alcohol, when I’m not paying attention or simply when the bathroom floor is slippery. Anyway, I have this cabinet with very sharp edges and corners. Very sharp. So I put Rubber Duck to the rescue!
