Group 3D Printer

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Overview

The group has purchased and assembled a Prusa Mendel 3D printer. This page gives some instructions on its use

Mechanicals and Electronics

The Prusa Mendel is a type of RepRap printer http://www.reprap.org/wiki/Main_Page . It uses threaded rods for the frame, with a total of 5 stepper motors... 1 for X, Y, and the extruder, and 2 for the Z axis. Our version uses a RAMPS v1.4 board, with a SD card reader and LED display panel for headless printing.

Software

There are 3 things you need to acquire in order to use the printer: slicing software which generates the GCODE (slic3r), printer controller software that measures temperatures and sends code to the RAMPS board (printrun / pronterface), and custom configuration software we have created specifically for this project (on github).

slic3r

You can acquire slic3r here: http://slic3r.org/ Slic3r takes STL files as input. Essentially what it does is take the STL solid and split it into a series of Z axis sections. Each section becomes a GCODE profile, which is used by the printer to make the objects. You can drop multiple objects in the Plater to print many at the same time, or you can rotate, scale, or duplicate items in the Plater as well. Important settings:

  • Print Settings
    • Layers and Perimeters -> Layer height default should be .36 mm. .3 to .4 works, maybe smaller down to .2 if everything is properly calibrated.
    • Infill -> Fill density should be between .1 and .5, Fill pattern rectilinear or honeycomb recommended
  • Filament Settings
    • If you change filament, measure carefully in 3 places and average the results. Put this in Filament -> Diameter

Once your settings are good and your part added to the Plater, click Export GCode to generate your gcode, which is then loaded into pronterface.

Printrun

Printrun is described here: http://reprap.org/wiki/Printrun Printrun (specifically, pronterface) connects to the printer, controls the motors, measures the temperatures, and sends the GCODE to the board for interpretation.

Configuration Files

Configuration files are very specific to each printer, and each type of filament. If you change printers, and sometimes if you change filaments, you will need to tweak the slic3r configuration files. Most likely, you won't need the firmware / Marlin config for normal operations. To get the configs, either ask someone at the space, or get them from here https://github.com/KnoxMakers/3d_print.git

Procedure

Create the GCODE

Open up slic3r. Go to File->Load Config. Load the above config. Drop your STL file in slic3r. Adjust settings as needed (default fine for most prints). Export G-Code to save it for use in pronterface software.

Connect to the Printer

Load Printer Interface (pronterface) software. Connect to printer... You may need to select the port to use.

Load the GCODE into pronterface

Preheat the bed

Go ahead and set the bed temperature to 130C (or whatever you're using), before homing. It takes a while, this will save you time.

Home the X and Y axes

In pronterface in the top left corner, near the big concentric circles, go ahead and hit the X home and Y home buttons. The mechanical endstops work for this reasonably well.

Home the Z axis

Here we get into some of the tedium / art of printing. Mechanical endstops get close but don't have the required precision (like .1 mm). What you will want to do is go ahead and hit Z home button. Then, click to raise the Z axis by .1 mm until you JUST see the head lift off the glass. Then, click down .1 mm until you are JUST ABOVE or JUST TOUCHING the glass. You need a clean extruder and a level bed for this to work well, but you'll find with some practice what is 'acceptable'. After you find your physical Z, you want to tell pronterface that the head is now actually at Z zero. The gcode command for this is 

G92 Z0

First Layer Adhesion

First layer can make or break your prints. You want something that looks a little squished, but not flat. Completely round is bad, and completely flat is bad. You want something in between. If your skirt isn't printing right, STOP the print, rehome Z, and then restart.

Special Tips

Hairspray for better adhesion

We have a super secret, super effective method to get ABS to stick to glass: Garnier Fructis Bamboo Extract Hairspray, extra hold. This stuff is STICKY. I recommend to reapply when there are VISIBLY MISSING places on the glass... the hairspray is somewhat bumpy or translucent... whereas clear glass looks like... clear glass. If there are big bare spots in the middle of the plate (or otherwise), CAREFULLY remove the glass, clean it with WARM or HOT water (cold won't remove the gunk), then reapply 3 light coats of spray, letting each dry in between.

SD Card printing

If you want to use headless mode, drop your gcode in a folder on the SDCARD in the reader, then using the dial, navigate to the Print option, then select your file, and press the dial in. It should start printing.

Levelling the bed

Levelling the bed is super important and sort of a pain. It's pretty darned level now. What makes it more challenging is it's 3 point levelling instead of 4. I recommend you leave this alone, but you can tell by moving to X, Y, and Z home, then moving the head around with pronterface to each corner (+180 mm X and Y) to verify the level. Ideally you want to test with a shim, something like 2 sheets of paper, or a leaf gauge.

Resources and Links

Space Notes:

Good Internet Links

LEGACY DESCRIPTION (needs to be cleaned or deleted)

The group is pooling resources to create a Makerspace owned 3D printer. Andronicus is leading the efforts, with a build goal deadline of 1/15

Current Status

As of 02/19/2013, the space printer is printing parts with some degree of accuracy. Hardware and software changes frequently.

Specifications

Financial Contributions

  • Adan
  • Dr. Strangegun
  • Issac
  • Sam
  • Shane

Things to Buy

Electronics

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