Getting Started with Skeinforge from Slic3r Using Printrbot 1403/1405

Just recently, I started looking at other slicers for my 3D prints. Slic3r was fine for getting started, and skimming the surface of 3D printing, but once I started printing my own models, and they became much more complex, Slic3r was far from perfect. After asking around, and doing a bit of research, I found that Skeinforge was my best bet. Unfortunately, finding pre-built profiles for Printrbots were almost non-existent. So, to help fix this issue, I'm writing this article on how to start moving over to Skeinforge.

Updated: 08.13.2014

Note: Skeinforge is by far one of the most complex and highly-sophisticated slicers out there, and if you want absolute perfection, expect to spend time accomplishing such. If you want something that "just works", then Slic3r is probably your best bet. There are no amounts of settings I can share to make it quicker. Each person has to spend time tweaking the settings to their printer, but I'm writing this to make the process a lot less frustrating, and possibly fun. 

Getting Started

One of the main reasons for writing this, is that the terminology used in Skeinforge, and other slicers, are completely different. So to help translate, I will explain how to setup the software, while making references to the Slic3r settings when possible.

To start, here are some basic settings for Skeinforge, which reflect the Slic3r Filament, and layer settings.

(PLA)
Extruder Retraction Speed: 1.0
Filament Packing Density (Extrusion Multiplier): 0.9
Layer Thickness  (Layer Height):  0.4
Center X/Y (Print Center): 42.5 (Half of your calculated bed size)

I'm giving these settings, simply to make things a bit easier. While I don't know all of my settings just yet, these are fairly basic settings you won't have to worry too much about. The layer height can be lowered down as low as 0.1 on a 1405, but 0.4 is a great place to start when tweaking the settings.

Understanding Skeinforge

There are a few key words I want to mention to make this a lot easier on you. First off is Feed Rate. This is the rate in which the extruder moves, or rather how the print head moves around on all axes. Next is the Flow Rate, the rate in which the extruder spits out filament to print the object. Skeinforge is setup to use a base Flow and Feed Rate for your printer, and then use multipliers to alter those rates while in certain situations. I would suggest to keep a calculator handy, so that you can check your settings, and make sure you don't set anything too high or too low.

To make this a bit easier, let's take a look at the settings in the 1405 firmware, specifically the Maximum Feedrates (mm/s):

M203 X125.00 Y125.00 Z7.00 E14.00

With these we can set the limit on the Feed Rate (125.0), Flow Rate (14.0), and Max Z Feed Rate(7.0) settings in Skeinforge. Your actual Feed Rate is up to you. The Travel Rate (when extruder is off), can be at 125, but your travel rate when extruding/printing you might want to dial down. Think of it as your highest speed setting in Slic3r. You can then set your perimeters, infills, supports, etc to a multiplier like 0.8 to run 80% of the base Feed Rate. While I'm configuring mine, I decided to use the base rate of 50 mm/s.

Once you understand the basic terminology, and operation of Skeinforge, you will find the rest to be quite easy when using their documentation on the wiki in tandem.

Alteration Files

After looking around the application, you'll notice a lot of references to gcode files. Skeinforge looks for these files in your user's directory, in a hidden folder called ".skeinforge", and then the "alterations" folder within it. Simply put your *.gcode files there, and Skeinforge will have no issues finding them.

Now that you know about these files, go into the Alteration folder mentioned above, and create a new file called start.gcode. Once you have created that file, edit it, and add this line:

G92 E0

The reason for this, is so when you start prints, that Skeinforge doesn't think that your extruder is at a certain position, and try to correct it. If you don't add it, you will probably find your filament being retracted out of the extruder, to where you won't print anything at all.

Printing Skirts

If you're like me, you want to have a few skirts printed around your object, before it starts to print. Unfortunately, the default download of Skeinforge only offers a few options for skirts, and only prints one skirt loop. To remedy this, you can download the newer version of the skirt.py plugin to add the option of Brim Width, which translates to the number of loops you want. You can find the newer file above, or from the Reprap forums here. Once you have downloaded the new plugin, use it to replace the old skirt.py in the following directory in your Skeinforge directory:

skeinforge_application/skeinforge_plugins/craft-plugins

Using this will make for better first layers, especially if you are still fine tuning your configuration. I use the width of 5, but you can change to whatever you need to make sure your extruder is stabilized before the actual print.

Calibration

Calibration will be a bit different with this slicer, and this is where the majority of setup time will be spent. To start, go to the Printrbot STL and Gcode Models page, and grab the FirstCube, and 3DEsprit Calibration Model STLs. Slice the FirstCube first, and make sure you can get it to print completely. It doesn't have to be perfect, but make sure that you can print it all the way to the last layer. Once you have the FirstCube printed, use my custom Calibration Model. I created this model specifically for calibrating Skeinforge, so that you can see exactly what you want to change in your settings to get the perfect print.

One thing I would advise is to have the GCode command list at your side. If you don't understand a certain setting, you can slice a model with that setting, and then look at the gcode to see what was changed. When doing so, you can see exactly what was changed in the code, and how the printer reacts. I did exactly this when checking certain flow rate modifiers, and later found in the GCode where the flowrate was changed at certain parts of the model. Using this method together with Repeteir's layer preview mode, will make it easy to track down certain layers, and how the GCode is setup for certain situations in the print. Not only that, understanding what is happening will help you create even better configurations.

3D Esprit's Custom Calibration Model

I wanted to briefly discuss the custom calibration model, to give you an idea of how it helps with calibration. This model is not of anything specific at all, but is setup to show many different printing features. It consists of a flat plane, with several inner islands that all have variable slopes. When you slice the model, look at each layer, and look to see how the printer will react to each one. Also, babysit the entire print, and watch as it works through every single portion of the model. At the end, the printer will create the bridge that goes over the two pillars, and one is further out than the other. I can check to make sure that each line is not sagging in the process of creating the bridge. Also, when the printer moves from one island to the other, make sure that there isn't any extra filament being left behind in the path. If there is, you can start working on the Dwindle plugin that will alleviate this issue.


Plugins

If you haven't noticed yet, Skeinforge has a huge list of menus full of options. Each one of these menus is called a "plugin". After several trial and error attempts, and searching on the internet, I finally found what I needed enabled. Here is what I have enabled for a simple print, without any extras:

Alteration 
Bottom
Carve
Cool
Dimension
Export
Fill
Limit
Multiply
Preface (always enabled)
Skirt
Speed
Temperature

This should give you a good idea of what you need to set to get started. Dimension is a big one, as it is the plugin that deals with your extrusion. If it's not on, you'll be printing with nothing at all.

Summary

Once you see a print out of this brilliant slicer, you will never want to use anything else. This is the feeling I'm having right now. Not only are the supports excellent, the infills reduce filament waste more than any other slicer I've used, my edges are extremely smooth with a 0.32 layer height, and that's with PLA! I don't want to give the wrong impression, but I think I can hold off on upgrades to use ABS for a bit longer now.

Updates

I will continue to update this as I continue to work more and more with Skeinforge, but I wanted to publish this as soon as possible since there seems to be a lack of documentation for this software when using it with a Printrbot. What I did find, only gave me a less vague description of different options, when compared to the wiki. Anyways, keep checking this page for additions, and I'll be sure to update the date in the title to reflect updates.