Kossel Clear

Kossel Clear Mini 3D printing using Slic3r in Windows 10 on the Powerspec PC

by D. Scott Williamson
April 20, 2018

Welcome to my end-to-end quick start guide to get you 3D printing on the Kossel Clear Mini delta 3D printer at Workshop 88.  This guide contains specific instructions that will guide you through starting and using Slic3r to prepare a 3D model for 3D printing, using the Octoprint web interface to print your model on the Kossel, and will let you know where to find some more advanced configuration options, but will not delve too deeply into the many advanced capabilities of Slic3r, or Octoprint.  Let’s get started!

If the Powerspec PC (to the left of the Replicator Dual 3D printe at the time of this writing) is not running, press the power button on the front to wake it.  Please do not shutdown or power off the machine, it will automatically sleep after a period of inactivity.

Run Slic3r: Find the icon on the task bar at the bottom of the screen.  Be sure to run Prusa3D Slic3r Workshop 88 because it has the profiles tailored to Workshop 88’s 3D printers.

Configure Slic3r for the Kossel Clear Mini 3D printer by making the following selections in the upper right portion of the screen:

Print settings: Kossel 0.20mm NORMAL
Filament: Kossel PLA 1.75mm
Printer: Kossel Clear

Drag STL or other compatible file(s) onto the platter in the 3D view.
(Browse interesting 3D printable models on https://www.thingiverse.com)

Arrange items for printing.  There is no multiple selection in Slic3r, you can only select and move one item at a time.  You can right click on objects to manipulate them including scaling and rotation.  Models will always be placed at zero elevation on the build plate so you don’t need to worry about that.

Click and drag the build plate or background (anywhere but on a model) in the 3D window to rotate the view, dragging with the center button will translate or pan the view, and the mouse wheel zooms.

Slicing and previewing

Click “Slice Now” under the Printer: selection to slice your model.  This prepares your 3D model for printing by calculating the many flat layers or slices of plastic that need to be extruded.

Select the “Preview” tab beneath the 3D display to view a rendering of the 3D printed sliced model including extrusion thickness.  By default, the skirt will appear green, perimeters are yellow, and infill will be pink.  The sliders allow to you to view all or a selected range of layers (slices) of your model.

Clicking the “Tool” checkbox to the bottom right of the display will cause the models to be rendered in the filament color.

Select the “Layers” tab beneath the 3D display to view the wire-frame tool-path of each individual sliced layer.  The skirt will be displayed in black, perimeters are red, and infill is blue.

These sliced preview windows are excellent for “proofreading” your model before exporting gcode to be printed or for troubleshooting your model if a print does not go perfectly.

Note: The Platter will appear blank if the model is not sliced or if settings change, it is easy to forget to switch back to 3D view to import and arrange models.

Saving gcode

Click “Export G-code” beneath the Printer: selection to save your gcode file for printing.  I suggest you create a folder for yourself in Documents on the PC and organize your files in there.

Saving your work

There is no way to save all your settings in one file (like a Makerware Thing file), but you can save your platter as an amf.xml file by selecting “Export plate as AMF…” from the “Platter” menu, and you can save your configuration “bundle” by selecting “Export Config Bundle…” from the “File” menu.

Printing with Kossel Octopi

Reminder: Unattended printing is not allowed at Workshop 88, you must be present for the entire duration of a 3D print.

In your web browser navigate to the Kossel Octopi server page here: http://kossel.local/
(You have to be on the Workshop 88 network)

It should automatically log in, but if you need to log in click the login button in the upper right corner and use the following credentials:

Username: workshop88
Password: workshop88isgreat

Turn the Kossel 3D printer on.  The switch is in back, low on the right side when looking at it from the front. (be sure to turn it off when you are done!)

Connect”  to the printer, if you see a “Connect” button on the left side of the screen, click it.  When connected, the “Connection” tab will collapse.

There are two ways to upload your gcode file to Octoprint:

  1. Click the “Upload” button on the lower left part of the Octoprint web page under the file list, navigate to where you saved your gcode file, select your gcode file, and click “Open“.
  2. Navigate to where you saved your gcode file in an Explorer file window.  Drag your gcode file onto the web browser and drop it on the left half of the screen to “Upload Locally” which will save it to the Raspberry Pi running Octoprint. (Dropping your file on the right half of the screen would be used to upload your file to an SD card in the printer.  We don’t use this functionality, there usually no SD card in the printer, nothing will happen).

In a few moments your file should appear at the top of the files list on the left side of the screen.

Note: If the Octoprint browser screen ever gets stuck with the gray overlay saying “Upload Locally” and “Upload to SD”, simply refresh the page.  This can happen when dragging files over the browser window without dropping them into Octoprint.

Click your file name or it’s “Load” icon that looks like a folder (fourth from the left of the 5 icons)

You can preview your model if you want using the “Gcode Viewer” tab at the top of the screen.

Click Print on the left in the State panel to print!

The printer should home but you will have to wait for the extruder to heat before it starts printing.  You can monitor the printer temperatures on the graph on the “Temperatures” tab in Octoprint.

Note: if you have to cancel a print for any reason (extruder/filament issues, model/slicing error, model breaks free from the bed…) it is best to turn the 3D printer off then back on and to “Restart Octoprint” from the system menu in the browser.  If this is not done, Octoprint may appear to work properly but stability issues and strange behavior have been observed in the past.

Be sure to turn off the printer when you are done.

Advanced Slic3r configuration


You may adjust print settings for your prints but please do not overwrite the settings files; a lot of work has gone into the configurations for each printer and they have been tested.

Print Settings

This is where you will be able to set layer height, perimeters, top and bottom solid layers, brim, and supports, ooze prevention (for multiple extruders), plus more advanced settings.

Coming soon:

Kossel 0.10mm DETAIL
Kossel 0.15mm OPTIMAL
Kossel 0.35mm FAST

Filament Settings

Here you may set the extrusion multiplier, extruder and bed temperatures, cooling, display color of a filament.  The Kossel is only capable of printing PLA (no ABS, PETG, etc.)

Printer Settings

These are carefully configured and tested.  There are no usable adjustable settings unless something like the nozzle diameter is physically changed. Please do not edit.

Workshop 88 Slic3r Settings

All of the Workshop 88 Slic3r settings are stored here:


The settings are also checked into the slic3r-settings repository in Workshop 88’s Git account and can be downloaded or transferred to other installations of Slic3r.


There is an additional folder called “unused” that contains backups of the settings that come with Slic3r Prusa Edition that we are not currently using (Prusa printer profiles, exotic filaments, etc.)

The original installation of Slic3r Prusa Edition configuration files can still be found here:

C:\Users\Public\Documents\Prusa3D\Slic3r settings MK2 190

We are using the Prusa edition of Slic3r, source and installation files can be found here:


Happy 3D-printing!











(Previous documentation, updated and kept for completeness)

Short version: To print something, upload an STL file to http://kossel.local while at the space, wait for slicing to complete, then click the print button.

The Kossel Clear 3D printer, a kit from Blue Eagle Labs, is set up in the front room. It prints with PLA filament. It’s well adjusted and prints most jobs with almost no manual intervention.

There are two ways to use the Kossel, either by using the web interface at Kossel Clear, or by connecting via USB. The web interface is quite reliable, and is preferable unless you have a special need.

The Kossel web interface is provided by the OctoPrint software running on a Raspberry Pi sitting next to the Kossel.