Difference between revisions of "Project BrundleFab"

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Revision as of 21:15, 30 September 2014

Electronics

Arduino

Seed Studio SD Card v3.1 Shield

Well, connecting to an Arduino Mega2560 doesn't just snap on and work. You need to route some pins:

MEGA Pin SD Shield Function
ICSP1 D12 MOSI
ICSP2 5v 5v
ICSP3 D13 SCK
ICSP4 D11 MISO
ICSP6 GND Gnd
D53 D10 SS

Use the arduino SD library, with a 'const int chipSelect=SS;' and you are good to go.

HP F4480

I am using a pile of trashed HP F4480 DeskJet printers as a source of motors, gears, and encoders.

Here are some information I have discovered about the internals of this printer:

Rotary optical encoder board

This board monitors the 1200 DPI optical encoder disk attached to the main paper handling roller in the printer.

It uses quadrature encoding, and can monitor both forward and reverse direction.

I am using the 'Encoder' library from the [1] Arduino library collection.

Pin 1 is the kerf on the CPU board connection

Pin Function
4 Output A
3 Vcc 3.3v
2 Output B
1 Gnd

Linear Encoder

The HP F4480 printhead carriage monitors a 1200 DPI optical encoder strip, which is the feedback to the carriage motor.

HP CB8605-60085 Printer Carriage Pinout


DC Motors

All three DC motors (printhead, paper handling, and scanner carriage) are driven at 30v, PWM at 10% for nominal operation.

The printhead and paper handling motors are larger driving gear motors, the scanner carriage motor is a small motor driving a worm gear.

Print Media

Granulated Sugar + Water

Process

  1. Lay down 10mm of granulated sugar
  2. Sift a layer of 1mm of granulated sugar
  3. Apply 1mm droplets of (colored) water to the granulated sugar via a needle bottle (unknown tip size)
  4. Go to 2. until part build volume is complete
  5. Lay down 10mm of granulated sugar
  6. Heat at 120C (250F) in oven for 1 hour
  7. Let cool
  8. Remove from build container, and remove excess sugar

Results

The resulting object was stiff, but easily crumbled. Water dispersion through the granulated sugar had an approx 5mm radius, and substantially filled in the interior of the part (wireframe cube).

BrundleFab Media Test Result - Granulated Sugar + Water.jpg

Analysis

  • Droplet size should be smaller
  • Either a finer granularity or pressure packing of the media should reduce the spot size of the print head
  • A food safe adhesive should be tried to increase bonding strength
    • In-powder adhesive (such as meringue powder) activated by water
    • In-suspension adhesive (such as egg whites)

Powdered Confectionery Sugar + Water

  1. Lay down 10mm of granulated sugar
  2. Sift a layer of 2mm of granulated sugar, and pack down to 1mm.
  3. Apply 1mm droplets of (colored) water to the powdered sugar via a needle bottle (unknown tip size)
  4. Go to 2. until part build volume is complete
  5. Lay down 10mm of granulated sugar
  6. Heat at 120C (250F) in oven for 1 hour
  7. Let cool
  8. Remove from build container, and remove excess sugar

Results

Sugar did not re-crystallize, I suspect the cornstarch at fault here.

Analysis

  • Powdered Confectionery Sugar is not suitable for printing, due to the cornstarch content.

Powdered Sugar/Meringue Powder + Alcohol/Water

  • Powder base is granulated sugar and meringue powder
  • Adhesive is alcohol and water

Procedure

  1. Lay down 10mm of powder
  2. Sift a layer of 2mm of powder, and pack down to 1mm.
  3. Apply 1mm droplets of (colored) adhesive to the powder via a needle bottle (unknown tip size)
  4. Go to 2. until part build volume is complete
  5. Lay down 10mm of granulated sugar
  6. Heat at 120C (250F) in oven for 1 hour
  7. Let cool
  8. Remove from build container, and remove excess sugar

Results

  • Sugar/Meringue powder is % by mass
  • Alcohol/Water is % by volume
Sugar Meringue Powder Water Alcohol Results
90% 10% 50% 50% Small droplet size (1mm), no capillary creep from the droplets; resulting object could be rinsed of excess powder

Analysis

  • Should be a sufficient working material, need to experiment with different ratios.

[File:BrundleFab-90-10-50-50-dry.jpg] [File:BrundleFab-90-10-50-50-wet.jpg]