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building my RepStrap 3D printer from salvaged printer parts

3D Printer made from Salvaged printer parts...

In the ongoing saga of building my RepStrap 3D printer from salvaged printer parts...

 

Update in the blog section: http://letsmakerobots.com/blog/unixguru/further-progress-framing-my-repscrap-3d-printer


The first axis is sorted out:



This is the printhead carriage salvaged out of a inkjet printer.  It basically consists of a DC gear motor driving a tensioned belt, pulling the print carriage across a high resolution optical encoder strip


 


There have been plenty of people do this before me, but this is my kick at repurposing salvaged printer parts.  


This is the print head circuit board from the carriage.  In the center, you will see the solder pads for the Optical Encoder Sensor.  My original intent was to keep the flat cables intact, and pull the signals off of those, but at about 50mil pitch... I can't even think about soldering that... 

(yeah, I'm getting old)


As they have already done the work of wiring the IR LED with a resistor to VCC, all I really need is four wires.  VCC/GND/Encoder Phase A and B. 

The Optical Encoder provides logic level outputs to the Interrupt pins on the Arduino.  The sketch below only addresses the X-AXIS for demonstration purposes, and only uses one Interrupt on Phase A, while polling the signal level on Phase B.  This provides half the resolution capable from this Quadrature encoder. 


In a future article, we will demonstrate using PinChange Interrupts to get the full resolution from this arrangement.

 

 

 

 

 

 

 

 

 

Code in attachment below!

 

 

 

 

 

This is the endstop sensor circuit.  I haven't wired it up to the Arduino as yet, but it is pretty straight forward. 







In the true nature of this project, I searched for a used motor controller to go with my Arduino .   Pictured here, is the Adafruit I2C Motor Shield V2 that was on my original robot.  This project will breath new life into it. 


This is a wonderful board in that it contains TWO dual h-bridge FET drivers for four DC motors, or two steppers, or one stepper and two motors... 




Wiring up the Optical Encoder.  Only four wires are needed...

 

 


12volt DC gear motor used to drive the carriage assembly. 







References:

 

http://playground.arduino.cc/Main/RotaryEncoders#OnSpeed

http://reprap.org/wiki/Optical_encoders_01

http://mechatronics.mech.northwestern.edu/design_ref/sensors/encoders.html

http://forum.arduino.cc/index.php/topic,17695.0.html

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 but will those belts be  upto the forces/weight of the carriages,, extruder tubing .. am thinking belt slipage?

I have no idea what the hotend + extruder + cable drag is going to add.  I've tested it with a 12oz (350gram) weight, and saw an expected reduction in speed, but cannot for certain say whether I'm going to get "slop" in a print due to drag/stretching.

 

It's all part of the education, I guess...

 

My wife is now on the "Once you're done this *almost free* printer  (I am purchasing RAMPS and Hotend/Extruder)  then you are going to spend a fortune on plasic, arent you?"

 

It just doesn't end...  lol...

 

Do need to talk to you someday about your success with the ATTiny  and I2C ... having spurious issues when the motor is running...

 

Well, that's not a problem for a guy like you. You can calm down your wife by starting a new project, the filament maker out of kitchen devices parts :-)

Maybe I should recycle plastic shopping bags into filament!  Or milk bags?

 

Something tells me that the smell of melting plastic would put me and my filament maker into the dog house for sure...

 

(Yes, I've told her that the printer is going to smell bad.. it's being relegated to the garage...)

Oh, do you have a schematic?

Good thread on the issue.

I'll send you the schematic and code of the trouble board tonight... maybe two sets of eyes...

I've got two separate power rails, and a "bit" of conditioning capacitor (47uf) on the board, as well as a ferite ring on the motor line... but yeah... the I2C signal drops as soon as the motor kicks in...

 

 

 

Ya, I'm through 3kg (spool and a half) of PLA and I'm just getting calibration to the stage I'm printing useable prototypes. Regarding I2C, I almost guarantee that is noise from motors messing with the bus signal. I've issues on my second board, although the first worked great. Ideally, if you have motors and an I2C on the same board they should have independent power sources, but the second best thing is effective decoupling capacitors.

Mr. Unix, if you pull this off, please don't tell me wife.  She keeps asking, "Couldn't you have just built one of those (printers) from those old scanners I've asked you to throw away?"

Hope you are well, sir. :)