Kimball Kaiser

21.05.06 DTS Printer Progress

This week was mainly about configuring the printhead to run synchronously with the movement of TinyZ. Before, we were running both parts independently and we have explored an initial step of combining the two.

The first step was understanding the outports the TinyG board actually supports, and it is quite a bit.

The TinyG board has 3 banks of outpins which can be seen on the top of this diagram of the board. These pins, as they are labeled, are meant to support things like a spindle, coolant, and a series of physical limit switches that can be attached to a CNC machine to avoid the machine from crashing into itself.

Here is part of our rather temporary setup for connecting the printhead to the TinyG board. As can be seen in this photo, we have chosen to go with using the outpin for "Coolant" which will be explained later on.

We can get 3V out of the the coolant pin when turned on. This 3V will then be directly led to our printhead setup to activate the code running our printhead. For some reason mostly unkown to me at the moment, when using the PWM and other various spindle control pins, we got much less voltage which would not be enough to trigger the internal pull up resistors in our printhead Arduino board.

Then, to get this 3V to trigger sending pulses to our printhead, we made some simple modifications to our printhead code to use the TinyG as an input to trigger running the pulses to the jets. See that code below (this is just running one jet currently):

const int TinyG = A5; int TinyGstate = 0; int outPin2 = 2; int outPin3 = 3; int outPin4 = 4; int outPin5 = 5; int outPin6 = 6; int outPin7 = 7; int outPin8 = 8; int outPin9 = 9; int outPin10 = 10; int outPin11 = 11; int outPin12 = 12; int outPin13 = 13; void setup() { // put your setup code here, to run once: pinMode(outPin2, OUTPUT); // sets the digital pin as output pinMode(TinyG, INPUT); // sets TinyG as input for printhead } void loop() { // put your main code here, to run repeatedly: TinyGstate = digitalRead(TinyG); if (TinyGstate == HIGH) { digitalWrite(outPin2, HIGH); // sets the pin on delayMicroseconds(5); // pauses for 5 microseconds digitalWrite(outPin2, LOW); // sets the pin off delayMicroseconds(1000); // pauses for 1000 microseconds } else{ digitalWrite(outPin2, LOW); digitalWrite(outPin3, LOW); digitalWrite(outPin4, LOW); digitalWrite(outPin5, LOW); digitalWrite(outPin6, LOW); digitalWrite(outPin7, LOW); digitalWrite(outPin8, LOW); digitalWrite(outPin9, LOW); digitalWrite(outPin10, LOW); digitalWrite(outPin12, LOW); digitalWrite(outPin13, LOW); } }

To control our machine from our computers, we are currently using CNC Js, which can be found here.

To actually toggle that coolant pin, the gcode for ON is simply "M8" and OFF is "M9." The tinyG cheat sheet for supported gcode can be found here.

And with everything working correctly, this is what happens! In the gif above, you can see me controlling the printhead through the tinyG board coolant outpin, by typing M8 and M9 in the CNC Js console.

And with the printhead and tinyZ working together, we got straight to testing it with some real gcode.

First, as the most difficult geometry to draw by hand, we went with with the circle.

We then moved on to doing some test prints that involved more than one line, which would involve turning the printhead on and off between when the gcode is meant to draw lines and when it is meant to traverse to the next line.

Here you can see some of our first print results. The circle, which is not absolutely perfect (yet) and a quick grid. There are hooks on the end of the lines because the gcode is acting as if we have lead in/out paths, which I will explain in a minute. Essentially we made an error for when the printhead should be turning on and off.

Here is that same grid with its gcode fixed.

To make gcode for our machine, we are currently using Mastercam and just pretending that there is a spindle attached as an end effector. This part of the process will definitely be improved and we are currently looking into some more compatible alternatives. However, there are few nuances to making this work the way we would like. First, because for the moment we have disconnected our Z axis, Z in and Z out movements help us understand in the gcode lines where there should be printed lines vs traverse lines.

For example, in the gcode produced by this file above, these Z axis movements then give us a logic on where to add "M8" and "M9" for ON/OFF. Yes, this means to do these prints, we have been manually scrolling through lines of gcode, and guessing where our ON and OFF commands should go...see the example of our print gcode for this file.

N100 G20 N110 G0 N130 G0 G90 G54 X2.5743 Y1.1906 N140 G43 H280 Z.25 N150 Z.2 N160 G1 Z0. F6.42 N170 Y.4268 F35. M8 N180 Z.2 F6.42 M9 N190 G0 Z.25 N200 Y.8087 N210 Z.2 N220 G1 Z0. F6.42 N230 X2.2678 F35. M8 N240 Z.2 F6.42 M9 N250 G0 Z.25 N260 Y1.1906 N270 Z.2 N280 G1 Z0. F6.42 N290 Y.4268 F35. M8 N300 Z.2 F6.42 M9 N310 G0 Z.25 N320 X2.1499 Y1.1906 N330 Z.2 N340 G1 Z0. F6.42 N350 Y.4268 F35. M8 N360 X1.8435 N370 Z.2 F6.42 M9 N380 G0 Z.25 N390 Y.8087 N400 Z.2 N410 G1 Z0. F6.42 N420 X2.1499 F35. M8 N430 Z.2 F6.42 M9 N440 G0 Z.25 N450 X1.8435 Y1.1906 N460 Z.2 N470 G1 Z0. F6.42 N480 X2.1499 F35. M8 N490 Y.4268 N500 X1.8435 N510 Z.2 F6.42 M9 N520 G0 Z.25 N530 X1.4511 Y1.1906 N540 Z.2 N550 G1 Z0. F6.42 N560 X1.7575 F35. M8 N570 Y.4268 N580 Z.2 F6.42 M9 N590 G0 Z.25 N600 X1.0495 Y1.1906 N610 Z.2 N620 G1 Z0. F6.42 N630 X1.356 F35. M8 N640 Y.4268 N650 Z.2 F6.42 M9 N660 G0 Z.25 N670 X.9544 N680 Z.2 N690 G1 Z0. F6.42 N700 Y1.1906 F35. M8 N710 X.6479 N720 Y.4268 N730 X.9544 N740 Z.2 F6.42 M9 N750 G0 Z.25 N760 X2.5743 Y1.3995 N770 Z.2 N780 G1 Z0. F6.42 N790 Y2.1632 F35. M8 N800 X2.4211 Y1.872 N810 X2.2678 Y2.1632 N820 Y1.3995 N830 Z.2 F6.42 M9 N840 G0 Z.25 N850 X2.1499 Y2.1632 N860 Z.2 N870 G1 Z0. F6.42 N880 Y1.3995 F35. M8 N890 X1.8435 N900 Y2.1632 N910 X2.1499 N920 Z.2 F6.42 M9 N930 G0 Z.25 N940 X1.7575 N950 Z.2 N960 G1 Z0. F6.42 N970 Y1.3995 F35. M8 N980 X1.4511 N990 Y1.7813 N1000 X1.7575 N1010 Z.2 F6.42 M9 N1020 G0 Z.25 N1030 X1.6043 N1040 Z.2 N1050 G1 Z0. F6.42 N1060 X1.4511 Y2.1632 F35. M8 N1070 Z.2 F6.42 M9 N1080 G0 Z.25 N1090 X1.0495 N1100 Z.2 N1110 G1 Z0. F6.42 N1120 X1.356 F35. M8 N1130 Y1.3995 N1140 Z.2 F6.42 M9 N1150 G0 Z.25 N1160 X.9544 Y2.1632 N1170 Z.2 N1180 G1 Z0. F6.42 N1190 Y1.3995 F35. M8 N1200 X.6479 Y1.7813 N1210 X.9544 Y2.1632 N1220 Z.2 F6.42 M9 N1230 G0 Z.25 N1240 X.5476 Y2.0036 N1250 Z.2 N1260 G1 Z0. F6.42 N1270 Y1.3995 F35. M8 N1280 Z.2 F6.42 M9 N1290 G0 Z.25 N1300 Y2.0968 N1310 Z.2 N1320 G1 Z0. F6.42 N1330 Y2.1632 F35. M8 N1340 Z.2 F6.42 M9 N1350 G0 Z.25 N1370 G91 G28 Z0. N1380 G0 X0. Y0. A0. N1390 M30 %

This gcode then results in the print above. No, we definitely did not get it right the first time...Hence, this is why we are definitely working on a way to automate this process for ON/OFF.