3D Printing

 

Work on this page continues.

Some background regarding me.  I am just weeks into 3D printing so I am no expert.  I am passing on my experiences and some of my conclusions might not be accurate.  Bear this in mind going forward.

This page will not address the assembly of the various 3D Printers available on the market.  It will discuss the process/steps necessary to go from design  to print.

Now having said this I would like to point out some considerations when making a RepRap Prusa I3 purchase.

  1. pay attention to how the machine provides the Z-Axis adjustment.  The use of a “vertical screw” is a good choice.  Mine requires two scress to mount the endstop to the frame and this makes it difficult to adjust the end stop.  Also it is difficult to get to this arrangement on my machine.
  2. your kit will come with lots of screws and nuts.  What it will not come with are lock washers.  Do yourself a favor and try to find metric (yes these nuts and bolts will most likely be metric) lock washers.  These machines experience lots of “shaking” during prints and you don’t want the parts to loosen up.  Trust me I know what I am talking about.
  3. Pay very close attention to the extruder design.  There are many different types.  My experience is with the MK8.  The MK8 comes in various configurations and to be quite honest my extruder has caused me the most heartache.  I will post a picture later of mine and some of the other options for a MK8.  As for the other types I have no hands on experience so I don’t consider myself qualified to comment on them.  If you read the various forums the extruder is a source of irritation for “new” users.  There are plenty of feed problems.  The problems are in some cases due to the extruder itself, but also to incorrect extruder temps, ambient air temps, extruder tension adjustments, and the like.
  4. How you tension the various axis.  Some offer a wingnut adjustment others offer nothing.  If you cut your belt wrong you will not be able to adjust it.
  5. Framing material – wood, plastic, aluminum.  There is one product that uses an aluminum frame.  At first I avoided it because I thought that with “all those wires” this type of frame might not be a good choice.  I have since changed my mind.  This unit is extremely well made, with tension adjustments for the various axis, and a screw adjustment for the z-axis.
  6. Get a heated bed.  You will want one later as your expertise grows and you want to try different materials.

The 6 items are just some of the considerations.  Others include electronics, power supplies used etc.

 

Here are the basic steps involved in 3d printing

  1. design the “print object” and export as an “.stl” file
  2. check the “.stl” file for quality/integrity
  3. slice the “.stl” file into gcode for printing
  4. print the object

 

Lets discuss the above 4 steps in greater detail

1.  design the “print oject”

There are many options for doing this.  Here is a list of software (mostly free) for this step:

a.  sketchup – free 30 day demo.  After 30 days reverts to a “free” product with some ofthe whistles and bells removed.  Still an outstanding product, with an easy learning curve.  Itis what I use.  You will need to get a plugin which allows you to export your object in “.stl” format.  Regardless of the CAD package you choose to use be sure that can export in “.stl”

Before starting your design make sure to set the degree of accuracy.  I chose to use accuracy to .001mm.  This really is “rocket science”.  You do this in sketchup by:  windows–>model info–>units–>precision field – there are two fields.  This would be something you should set in any CAD application before starting to draw.

b.  FreeCad – also a great product but comes with a steeper learning curve

c.  Blender – for experienced users.  Might be overkill for 3D priting.

d.  Autodesk123D –  also good with a minimal learning curve

There are many others to choose from so pick the one you know or if this is your first time be prepared to spend some time learning the product.

2.  check the “.stl” file for integrity

Most all CAD packages export in “.stl”.  Be sure that yours does.  After you have designed your object it might look like it is ready to print.  Unfortunately it might not print because of hidden errors.  This brings us to this step.  There are applications you can run your “stl” file through to ensure integrity of your file/print object.  The one I am familiar with is NetFabb –  a free download.  This application has the ability to identify and fix problems in you “.stl” file so that you can re-export it as a “fixed” “.stl” file.  For example if your “.stl” file is called “yoda.stl” then it will, if it can, fix your file and re-export it as “yoda-fixed.stl”.  This file can then be loaded into your “slice” program to generate the machine code necessary for your printer.

Process:

netfabb – load drawing

A.  fix errors

Extras -> new analysis –> std analysis

Extras –> repair part

automatic repair (lower right part of screen)

default repair (select from popup)

execute

update (from right part of screen)

apply repair

remove old part ( from popup)

yes

B.  orient file

part

move

to origin – select

translate

C.   save as new stl

part

export part

as stl

 part will have the same name but look like:  {filename}repaired

you will load this file into your print application

3.  slicing your print object

Again there are many free such applications to choose from but I use slic3r and that it what this writeup will cover.  Because slic3r is part of the print application I use I will skip its discussion here and cover it in step 4, “print the object”.

4.  print the oject

At tis point you have designed the object you want to print, checked its integrity and now you want to print it. My choice for 3D printing is RepetierHost.  It is a free download and relatively easy to use.  Just spend some time with it and you should pick it up quite easlity.

Process;

a.  Load your “yoda-fixed.stl” (or what every your files name is)

b.  select the “slicer” tab – be sure to select slic3r and press the slic3r button.  This will generate the machine code that gets sent to the printer.  If your printer is ready (extruder and bed have reached their set temperatures) press the print button.

What follows is a video:

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