Evolution of a Blog

This blog has evolved as I have as a maker. It starts at the beginning of my journey where I began to re-tread my tires in the useful lore of micro electronics and the open-source software that can drive them. While building solutions around micro-electronics are still an occasional topic my more recent focus has been on the 3D Printing side of making.

Monday, June 8, 2015

Back to "Only" Two 3D Printers

After 18 months of good service the Prusa I3 has left the building.   A kind gentleman came to collect it last night after winning a bidding war for it on eBay.  It was almost sad to see it go but I think it will have a nice home!  This post will serve as a requiem to the Prusa I3 as I encapsulate some key aspects of its operation for the new owner.

Prusa I3 Workflow

  1. I use Sketchup as my 3D drawing tool as I have been familiar with it and find it easy to use for both 3D modeling and for other things like room design.  There are a lot of other tools many of which are discussed here.
  2. Once something is designed and ready to print an "STL", or stereo-lithography, file is exported from Sketchup.   STL files are available from a number of sources and can be downloaded and printed easily.  It seems like the defacto source for 3D printable models is Thingiverse.  My stuff on Thingiverse is here.
  3. Once you have an STL file you need to convert it to commands the printer controller will understand.   This is called slicing and results in a file of G-code commands.  A 3D Printer is basically a numerical control machine and that is the heritage of the G-code language.  The slicer that I used with the Prusa I3 was Slic3r.
  4. The profile that I developed for the Prusa I3 can be found in the Prusa I3 zip file that is available here on Google Drive.
  5. Once a G-code file has been created by slicing the STL file it is ready to print!  I use Printrun for this purpose.
  6. Prior to printing the build platform on the printer should be prepared.   I use a paper towel with some window cleaner and a little acetone to do this.   I then spray the surface with a little hair spray as I have found this to work great for getting prints to stick!  Not all hair sprays are created equal so I use Loreal!
  7. When the print has finished give it a couple minutes to cool and it should pop off easily.  A craft knife can be used if it is well and truly stuck.
  8. Finally, a key part of my work flow from time to time has been to reach out to the RepRap community via the RepRap Forums for help!    The folks out there have been very helpful though sometimes they will ask you to read the manual!

Build Platform Leveling on the Prusa I3

  1. The common leveling practice is to get the nozzle to within a piece of standard paper thickness of the build platform...uniformly across the entire surface.   You do this by measure at each corner and in the center.   
  2. First, however, you start with getting the platform in approximately the right position using the center as your measurement point.
  3. There is a knob located just below the x-axis stepper driver that tunes the position of the z-axis end-stop.  Turning this counter clockwise  causes the extruder to be lower and vice versa.
  4. Once you have gotten the above adjusted it is time to work on the four corners.  They are adjusted using a Torx T10Hx50 to turn the bolt for the adjustment while you hold the thumb wheel as a lock.  Turning counter clock wise will lower the platform and vice versa.
  5. The paper test, in my opinion, is only a starting point.  I use a bed level print to get the final level of adjustment.   There is one located in the Calibration folder of the files located on Google Drive (bedlevelwill.stl).  This is probably not a best practice but I have been known to adjust the bed while this calibration print is being extruded!

Prusa I3 Firmware

My Prusa I3 is controlled by a marriage of a Ramps 1.4 board with a micro controller, the Arduino Mega.   It is the Arduino that takes the G-code you generated above and translates that into commands for the stepper motors that are driven through the drivers on the Ramps board.   All this while the Arduino also monitors various inputs that also come by way of the Ramps board (three end stop detectors and two thermistors).   Heat settings for the build platform and for the extruder are also managed by this configuration.

All of the above happens under control of the firmware running on the Arduino.   My firmware of choice is Marlin and a copy of the configured firmware that is currently drive the printer is located in the Marlin folder of the files located on Google Drive.  Hopefully this will not need to be changed!  If you were to want to update the micro controller you would need the Arduino development environment.

No comments:

Post a Comment