03. Getting Started - The CNC Workflow

The Vectric Workflow

The Example Project will step you through all the stages of creating, toolpathing and cutting a simple line drawing. Most CNC projects share many common concepts and steps so before we complete our practical project, let's run through them.

The structure of a Vectric Job

All the information needed to describe a single CNC project is contained in a Vectric Job document (when saved they have the file suffixes *.crv or *.crv3d). A new job always begins by defining the area of a sheet of physical material that you intend to cut with your CNC machine.

Most jobs typically only involve one sheet of material, but more complicated projects may comprise multiple materials. Don't worry, your job's primary material sheet can be updated or new sheets of material added to your job later, as your design develops.

The drawings & images used to work on a material sheet can be created on layers to help manage more complicated designs. Similarly 3D model components can also be organised onto levels. By default there is always at least one layer and one level for each sheet in a new job. You can add more layers and levels to help organise more complicated projects.

Once your material sheet has been created in the Job Setup form, the software will show you a 2D & 3D view of your design space (which matches the dimensions of your current material sheet), each in their own window.

Above the view windows is the main toolbar which allows you to navigate through the structure of your CNC job and see what is currently being displayed in view windows below. It shows you the material sheet, design layer and 3D model level that you are currently working on (referred to as 'active').

What you see in the 2D & 3D design views below will reflect these current settings and any new shapes, components or toolpaths will be created in the active locations indicated. You can also change the active sheet, active layer or active level at any time directly from these controls.

More advanced projects can also represent both sides of a sheet of material. For a two-sided project an additional control above the views shows which side of the sheet is currently active. You can view the drawings, models and toolpaths associated with the top and bottom surface of each material sheet and swap the active side of the sheet in a consistent way to the other controls.

Initially your job will be empty and so your views will be blank, but in due course, Vectric's view windows will show all the layered drawings & images, 3D model components & toolpaths for the currently active material sheet.

The currently active locations are the same for both the 2D & 3D views i.e. creating a vector shape will place it on the same active sheet and active layer regardless of whether the 2D or 3D view is used.

You can, however, toggle the visibility of object types in each view independently using the visible items toolbar at the top of each view. This is helpful for focusing on different areas of your job at each stage of creating your CNC project.

Many of the software's tools can be used directly in either the 2D or 3D view.

In V12 some tools have not yet been extended to allow full interaction in the 3D - this is an ongoing transition. If in doubt, try click

Import, Draw or Trace artwork

Computer images are most often represented as a grid of coloured squares - these images are referred to as bitmaps and their constituent coloured squares are called pixels. Except for a few very specific cases, this representation is not *directly* useful for toolpath creation. Computer drawings (from CAD or illustration applications) are very different and are instead built from mathematically defined lines & curves.

This type of representation is referred to as vector or contour artwork. Vectric software can use both bitmap and vector artwork, but most types of toolpath can only be created from vector drawings. Suitable bitmaps with bold regions of similar colour (for example logos, cartoons, icons or signs) can, however, be used to create vectors from which many types of toolpath can then be generated - this process is called bitmap tracing.

Some external artwork file types contain only bitmaps (e.g. BMP, PNG, JPG), some contain only vectors but many can contain both (e.g. PDF, SVG, DWG/DXF).

Use the design artwork to create toolpaths

We use the vector artwork to define the shapes we want to cut. It is important to emphasise that the toolpath (the actual cutting moves your machine must make to leave your intended shape) is rarely, if ever, a direct conversion of the original artwork. The toolpath must be created taking into account a complex interaction of the material, your CNC machine's capabilities and the shape of your cutting tool.

"Sculpture, per se, is the simplest thing in the world. All you have to do is to take a big chunk of marble and a hammer and chisel, make up your mind what you are about to create and chip off all the marble you don’t want." - Paris Gaulois, 1879.

Toolpaths are therefore generated from source vector artwork but once created they are almost entirely indepenendent of the artwork that created them. Moving, editing or even deleting the source artwork used to generate a toolpath will not affect the toolpath - it must be actively re-calculated to reflect any changes.

This is a carefully considered Vectric design principle - although you may be prompted that a significant alteration to your job has occurred - your toolpaths will never change automatically 'behind your back'!

That said, toolpaths do retain a handy reference to the artwork that created them. If you choose to edit a toolpath it will try to locate it's orginal source artwork and re-select it. At this point you can simply recalculate it to reflect any changes you have made to that source artwork, but you can also choose to select additional or entirely different artwork.

Vista previa

As we've discussed, the actual motion of your CNC machine (the toolpath) required to cut al shape can be complex and difficult to interpret.

Luckily your software provides an extremely accurate preview of any toolpaths that you create by simulating them in a block of virtual material. In the Example Project we will use the Toolpath Preview to verify that the toolpaths are producing the shapes we want (and we can easily corrected them if not)!

This simulated preview is a hugely beneficial step that ensures you minimise costly mistakes in the real world (we all make them from time to time) but it also allows you to check the surface finish you can expect from different strategies under different conditions.

The Toolpath Preview uses exactly the same data that will be sent to your CNC machine. You can be confident that any cutting and surface finish issues that occur at the machine but which are no visible in the Toolpath Preview are almost always caused by a physical problem with the machine setup or tooling, which makes finding and fixing them a lot quicker!

Exporting the toolpath

Now we will be ready to export the toolpath, in the right format, ready to be loaded into our CNC machine's controller. Saving the toolpath will make use of a Post-Processor that is specific to your CNC machine. It will translate the movements contained in the toolpath into a toolpath file that is in the specific format required by your CNC machine's controller to load and run.