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CNC Guide

A guide to using the Shopbot CNC machine in MAKE ll at Library 21c

Editing Objects

Edit Objects section of the Drawing PanelThis section covers the various tools available in the Edit Objects section of the Drawing Panel. Top to bottom, left to right, the options are:

Selection cursors Icons for three types of selectors - The first cursor allows only for object to be selected, not manipulated in any way. The second cursor allows for the editing of individual nodes (vertices) and line segments on an object. Editing any nodes will strip away any special characteristics of the object (e.g a text box will no longer be editable text, but a generic object in the shape of letters). The third cursor is for transforming objects as a whole with the ability to resize, rotate, and move the object by clicking and dragging the anchor points.

Group/Ungroup Icons for grouping & ungrouping - Grouping objects allows for the software to temporarily treat multiple objects as a single object. Any transformation to the group will be done to all objects in the group and when creating toolpaths it will be done to the entire group. Objects do not have to overlap to be grouped and can be ungrouped using the fifth button in the first row.

Measure/Inspect Icon for the Measure/Inspect tool - This allows you to measure the distance and angle between two points, the length and position of a line segment, and find the area and perimeter of a closed vector. If you are working with 3D models you can also get a preview of a cross section of your choosing.

Merging Vectors Icons for 3 merging tools and 2 triming tools - These options options on the second row allow you to merge multiple vectors together into a single object. Note that this is permanent, unlike grouping objects.

  • Weld - The objects are combined and all interior lines are removed.
  • Subtract - The last object selected is used to "cut away" from the others, removing that object and any overlapping parts from other selected objects.
  • Overlap - Similar to subtraction except that only the overlapping parts remain.
  • Trim - Attempts to automatically merge objects by removing overlapping areas. This works in many cases, but is not perfect - if it does not do what you need try selecting objects in a different order or use one of the manual merge tools.
  • Interactive Trim - Similar to Trim, expect you click on specific segments to remove. This may have unintended results such as the creation of open vectors, however any changes can be undone using any of the Undo commands.

Vector Validator Icon for Vector Validator tool - This module checks for common design errors:

  • Zero-length spans - Where the distance between two connected nodes is zero, resulting in unnecessary nodes. This is a common issue when importing files from other programs. Note that the nodes have to be in the exact same position to be flagged - nodes that are imperceptibly close to the human eye will not be flagged. It also only flags nodes that are adjacent on the object - if the start and end points of an open vector overlap it will not be considered an error even though this can cause issue while creating toolpaths. If any zero-length spans are detected there will be an option to automatically clear them by merging the nodes.
  • Overlaps - Where two line segments from different objects overlap either in whole or in part. This is a common error when copying and pasting as the pasted object is placed directly on top of the original. Note that is is not always an error and should only be corrected if the creation of overlaps was unintentional.
  • Intersections - Where two line segments from one or more objects cross at a single point. As with overlaps, the existence of intersections is not always an error that needs to be corrected.

If any objects are selected the validator will only look at those, and if there are any overlaps or intersections with unselected objects they will be ignored. If no objects are selected the validator will check everything on the current workspace.

Create Fillets Icon for fillet creation tool - Rounds the corner of objects in one of four ways. Normal fillets round the corner by curving the edge inward, Dog-bone and T-Bone fillets create extrusions to help slotted pieces fit together, and Plasma/Drag Knife fillets are used when working with plasma cutters and drag knives (neither are available at PPLD). Clicking on an existing fillet will remove it.

Extend Icon for Extend Vectors tool - Extends a line segment until it reaches another line segment. Click on the line segment to be extended and a dashed pink line will appear, then click the target line segment to confirm and extend the line segment. Note that this does not connect the two line segments with a node or close off vector objects. The end node of the extended line will simply be sitting on the target line segment.

Fit Curves to Vectors Icon for Fit Curves to Vectors tool - Alters vectors (open or closed) by converting the line segments into circular arcs, bezier curves, or straight lines. This may result in simplified objects or smoothed curves.

Vector Boundary Icon for Vector Boundaries tool - Creates closed vectors that loop around all selected objects. Offset boundary creates curved boundaries a specified distance around objects - intersecting objects are treated as single objects. Note that offset boundaries may be different than when the Offset tool is used - most notably that the offset will automatically merge any overlapping boundaries where as it will not here.

Rubber band boundaries create tight, straight lines around selected objects regardless of whether or not they overlap. If both offset and rubber band options are selected, the boundary will be a single curved vector the goes around all selected objects the specified distance away.

Edit Picture and Crop Bitmap Icons for Edit Bitmaps and Crop tools - Edit Picture allows for basic editing of bitmap images that have been imported - adjustments can be made to the contrast, brightness, and gamma, as well as inverting the colors and converting to grayscale. There are also options to add rectangular or oval borders. The crop tool simply trims the image to fit inside a closed vector. These functions can be useful to quickly prepare a bitmap for tracing (see the "Vectorizing / Tracing Bitmaps" tab for more information), however complex edits will often be easier to make in a dedicated image editing program such as GIMP.

Join Vectors Icons for four Join Vectors tools - The last row provides four options for closing vectors by connecting the start and end nodes. The first option allows for a tolerance to be specified - any nodes within that distance will be automatically moved to the midpoint and joined. The other three options close vectors by creating a straight line or curve between the start and end nodes, or by moving the two nodes to the midpoint and joining. Note that any of these options may produce unexpected results if multiple objects are selected as it will attempt to join the end and start nodes of the objects instead of closing off individual objects.