Wednesday, October 27, 2010

Building a Prusa i3 printer - Your first print

Videos are worth 10,000 words, so here they are.  The words are below.

Here's a quick demo of starting a print


And a demo on changing filament

Getting ready

3D objects are described by STL files.  You can get them from many sources; directly download them from sites such as Youmagine.com or Thingiverse.com, or create them yourself in a variety of programs such as Google Sketchup (STL output requires a special plugin) or OpenSCAD or many other such programs.

Once you have the STL file, it needs to be translated into a series of command (such as “move 3 millimeters X, 5 millimeters Y”) in what is called “G-Code”.  G-Code is actually very generalized and is used by many motion control systems such as CNC routers.


The software that I most like for generating G-Code at this time is called Cura  Install it and run it, go through the setup wizard.  You will need to make a good measurement of your filament diameter.  Be sure to measure in a few locations along the first few meters of filament in case it varies (good filament won’t vary much).  Put that number into the filament diameter field.


Now load your STL file by either drag/dropping it onto the print area or File/Load Model File.  After a short delay it should show the object and give an estimate of print time (always optimistic) and amount of filament used (should be exact).



Printing

Hit File/Print (or ctrl-P). 

You will have to determine the best temperature to extrude your plastic at. For PLA, start at 190 and see how it goes.  If it’s too hot, the plastic will be very runny and may just blob out of the hotend instead of flowing evenly when driven by the motor.  Hotter prints are generally stronger but overhangs may droop and small objects may melt during printing.


You’re ready to print now.  Read the following paragraphs COMPLETELY then hit the Print button.


Once you start to print, the first thing the printer will do is to lay down a “skirt” which is just a line of plastic around the object to be printed.  The line of plastic should be just slightly squashed down so that it’s about twice as wide as it is high.  This is not terribly critical, but if it’s too low it will squash flat, smear all over and cause a mess, and if low enough will block the plastic coming out of the nozzle and may cause the filament to strip in the drive.


If too high the plastic won’t stick well to the surface and may just drag around after the nozzle instead of forming your object.


If you don't like what's happening on the skirt and first layer, click "Cancel print" - it will take a few seconds for the printer to finish what's already been sent to it.  Adjust whatever you want (Z axis up or down, or whatever) remove the plastic from the print bed and try again.


Printing is a little bit of an art form.  Expect to play around a bit before getting really good prints.  There are examples of printing disasters on the “3D print failures on Flickr” link to the right.

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