How to Apply Custom Toolpaths for Thin Walls and Bosses

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When processing an STL file, smaller or larger toolpath widths are sometimes required to achieve proper fill for certain portions or features of a part. While changing the tip or modifying global toolpath settings for the entire part will generally work, oftentimes it is unnecessary. Custom Groups provide a means to specify different toolpath parameters for an individual curve or curves.

The following tutorial is brought to you by Stratasys:

  1. Step 1: Examples

    Examples include:

    • Features too small to fill using the default toolpath width

    • Features requiring reinforced walls such as bosses and anges

    • Areas that require different fill styles

    A common situation requiring custom toolpaths is when the default toolpath cannot fill in the space between two walls, resulting in voids and weak wall strength (Figure 1). This is corrected by modifying the toolpath width parameter (Figure 2).

    A similar situation arises with bosses, holes and anges where the default toolpath results in small gaps between the contour (outer wall) and raster (in fill) (Figure 3). This is corrected using additional contours applied with custom toolpath parameters (Figure 4).







  2. Step 2: Options

    Custom Groups are accessed from the Toolpaths drop-down menu (Figure 5). When creating a new group, all of the options and parameters that can be modified are displayed (Figure 6).

    The key parameters that eliminate gaps between contours and reinforce walls around bosses and holes are Contour width, Raster width and Contour controls.

    Modifying contour width – Eliminates gaps between single contours by adjusting contour widths so that the contours touch.

    Modifying contour and raster width – Eliminates gaps between two contours by adjusting the contour width and raster width such that the gap is raster filled.

    Strengthening features with additional contours – Eliminates gaps at the contact point between raster and contour by using multiple contours. Linking the contours joins successive contours, improving seam quality and reducing porosity. This provides additional strength if the hole will be drilled or tapped.

  3. Step 3: Modifying Contour Widths

    STEP 1: Configure the modeler.

    STEP 2: Open, orient and slice the STL file.

    STEP 3: Click the toolpath icon to create toolpaths. View the toolpaths in top-down view.

    STEP 4: Identify the area and layer(s) where a void exists between contours. Measure the total width between contours and divide by 2. Make note of this value for use in Step 7.

    STEP 5: From the Toolpaths menu, select Custom groups.

    STEP 6: Click New to create a new custom group. In the Toolpath parameters window, give the custom group a name.

    STEP 7: Under the Contour parameters section, select a size from the Contour width drop-down menu (Figure 7); it should be equal to the value you made note of in Step 4. Alternatively you can type the value into the field. Click the green check mark to confirm your selection.

    STEP 8: Select the desired curves using your cursor and click Add. All curves that are added to this group will have the toolpath parameters you defined.

    STEP 9: Click the Z toolpath icon or the G toolpath icon to regenerate the toolpaths for the layer or group.

    STEP 10: From the Toolpaths menu select Shade Toolpaths.

    STEP 11: Confirm that the gap between the contours has been eliminated, but the overlap between contours is less than 0.025 mm (0.001 in). If a gap still exists, modify the custom group values and regenerate toolpaths.

    STEP 12: Modifying Contour Widths procedure complete.

  4. Step 4: Modifying Contour and Raster Width

    STEP 1: Configure the modeler.

    STEP 2: Open, orient and slice the STL file.

    STEP 3: Click the toolpath icon to create toolpaths. View the toolpaths in top-down view.

    STEP 4: Identify the area and layer(s) where a void exists between contours. Measure the total width between contours and divide by 2. Make note of this value for use in Step 7.

    STEP 5: From the Toolpaths menu, select Custom groups.

    STEP 6: Click New to create a new custom group. In the Toolpath parameters window, give the custom group a name.

    STEP 7: Under the Contour parameters section, select a smaller size from the Contour width drop-down menu. Alternatively you can type the value into the field.

    STEP 8: Under the Raster fill parameters section, select a size from the Raster width drop-down menu (Figure 8). Alternatively, you can type the value in this field. Click the green check mark to confirm both selections.

    STEP 9: Select the desired curves using your cursor and click Add. All curves that are added to this group will have the toolpath parameters you defined.

    STEP 10: Click the Z toolpath icon or the G toolpath icon to regenerate the toolpaths for the layer or group.

    STEP 11: From the Toolpaths menu select Shade Toolpaths.

    STEP 12: Confirm that the gap between the contours has been raster filled. If a gap exists, modify the custom group values and regenerate toolpaths.

    STEP 13: Modifying Contour and Raster Width procedure complete.



  5. Step 5: Strengthening Features with Additional Contours

    STEP 1: Configure the modeler.

    STEP 2: Open, orient and slice the STL file.

    STEP 3: Click the toolpath icon to create toolpaths. View the toolpaths in top-down view.

    STEP 4: Identify the area and layer(s) where additional contours are needed.

    STEP 5: From the Toolpaths menu, select Custom groups.

    STEP 6: Determine the desired number and width of contours.

    STEP 7: Click New to create a new custom group. In the Toolpath parameters window, give the custom group a name.

    STEP 8: Under the Contour parameters section, select Multiple contours from the drop-down menu (Figure 9). You may change the contour width from the default value based on the calculation in Step 6. Select the Number of contours from the drop-down menu. This is the number of contours this group of curves will have.

    STEP 9: (Optional) Under the Contour controls, select the checkbox for Link contours (Figure 10).

    TIP: Selecting the checkbox to Apply contour style to selected feature only (Figure 11) will apply Contour parameters only to the selected part curve (feature-based contours) (Figure 12). 

    STEP 10: Click the green check mark to confirm your selections

    STEP 11: Select the desired curves using your cursor and click Add. All curves that are added to this group will have the toolpath parameters you defined.

    STEP 12: Click the Z toolpath icon or the G toolpath icon to regenerate the toolpaths for the layer or group.

    STEP 13: From the Toolpaths menu select Shade Toolpaths.

    STEP 14: Strengthening Features with Additional Contours procedure complete.



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