PyCam Settings

This post will describe using PyCAM for generating g-code from STL files to be used to cut on the CNC mendel. You can download PyCAM here.


Open up PyCAM. By default PyCAM will load a PyCAM soap bar like object. To open the STL file you would like to cut, go to File -> Open Model. The model you selected now should appear in the PyCAM Visualization window. You can look at the object by a combination of the following methods:

  • Clicking the Center, Front, Back, Left, …, etc. Buttons
  • Holding down the left mouse button and using the mouse to rotate around the current center
  • Holding down the right mouse button and using the mouse to zoom in and out towards or away from the current center
  • Clicking down the mouse wheel (not scrolling) and using the mouse to move up, down and side to side

Back to the main window. Click Model tab -> Move Model -> To Origin. Still under Move Model, set X and Y to 5.00 and click Shift. This moves the model’s starting position to be 5×5 mm away from the home position. For more complicated prints and different material sizes, you may need to fiddle with where you put the model, but for most cases half a centimeter away from home works well. During the To Origin and Shifting, you may have noticed the model in the visualization change positions. The visualization window is a great help in figuring out how the model will be positioned.

Next, click the Tools tab. Click New. Change the tool’s name to something like CGAR Dremel. Make sure it is Cylindrical. Measure the diameter of the bit and change Tool Diameter to the diameter of the bit in mm. The spikey bit (Tile Cutter bit — see Hardware)we have been using has a diameter of 3.2 mm. Ignore the settings for Feed Rate and Spindle Speed.

In the window menu, Settings -> Save Tasks Settings as… Change the filename to something like CGAR.conf.

IMPORTANT: Everytime you make changes to the tool settings or any of the options from this point on remember to go to Settings -> Save Task Settings. When you open up PyCAM, you can go to Settings -> Load Task Settings -> CGAR.conf and have all of your options loaded up for you. Otherwise, you will need to redo this stuff all over again each time you open up PyCAM.

Click Processes tab -> New button. Change name to something like CGAR Cutting. Select Contour (follow). Set Max Step Down to 15.000. Click Settings -> Save Task Settings.

Under the Bounds tab -> New. Give it the name Custom. Set Margin Settings -> Fixed Margin. The Bounds tab deals with the dimensions of the material you are going to be cutting into. Usually, I use 10% margin as we will see later, but it good to have a custom boundary you can alter when you have specific dimensions in mind. You can alter the dimensions by changing the X, Y and Z upper and lower boundaries. The results of these changes can be seen in the Visualization window the by the accompanying changes to the gray bounding box around the model. Click Settings -> Save Task Settings.

Now, we combine all the previous steps together. Under the Tasks tab, uncheck Rough, Semi-Finish and Finish. Click New. Name this task CGAR Cut Task. Change Tool to CGAR Dremel (3.2). Change Process to CGAR Cutting. Change Bounds to 10% margin. Click Settings -> Save Task Settings. Depending on the thickness of the material, you will need to change the safety height, the Z height at which the bit can move XY freely without cutting into the material. Go to Settings -> Preferences -> GCode -> Safety Height. Set the Safety Height to be about 3-5 mm above the thickness of the material you are going to be cutting. Check Load custom task settings on startup. Navigate to and select cgar.conf. Click Close. Under the Tasks tab, make sure CGAR Cut Task is selected, click Generate Toolpath.

PyCAM should now start processing the movements required to cut the model. You should see the movements in the Visualization window.

Dislike how the g-code was formed? You may need to try different settings in Process. For more information consult the help page. After it is complete and you are happy, click on the Toolpaths tab. Click Export visible. Save the g-code with the desired filename. Your g-code for the part should now be ready.


Engraving does not work with STL files, but instead works with SVG, DXF and PS files. To make simple SVG files you can use this free, online SVG editor: If you want to convert a png or similar format into SVG, I use the free, online component of

Open the SVG file. Shift the model as described in the steps above. I usually shift by 5.0, 5.0, 5.0 to 9.0 for X, Y and Z respectively. You can then use Gravure under the Tasks tab. Make sure to use the CGAR Dremel size (3.2 or whatever size you are using). Click Generate Toolpath. Make sure the toolpath looks reasonable and then export the g-code as usually done with an STL model.


PyCAM is used to generate a cutting path in g-code for the Mendrel to cut out the desired object. To actually cut out the object see the post on cutting.

  1. Mendel Background
  2. Hardware
  3. Electronics
  4. RAMPS
  5. PyCAM
  6. G-Code
  7. Cutting

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