ShopBot

About the Tool: Subtractive manufacturing. Uses CNC (Computer Numeric Control) to remove material from a workpiece in a selected order.

Location: Project Build Space (Room 115)

Access: Assisted fabrication

File types:
2D file formats: .dxf, .dwg, .eps, .ai (adobe illustrator), .pdf
3D file formats:  .stl, .dxf, .3ds, .obj, .skp, .v3m, .lwo, .3dm (Rhino 3D model)

Materials: 

  Allowable Materials Restricted Materials
Wood Solid wood
Plywood
MDF
Pressure-treated wood
Painted wood
Stained wood
Wood with knots, staples, nails
Wax Machinable wax  
Plastic HDPE
Delrin
 All others
Foam XPS foam (pink/blue extruded polystyrene insulation)
Machinable foam (Urethane)
 
Metals None No metals allowed!

Build size: 

Allowable Material Height

Material thickness depends on the size of the bit. Please note that smaller bits significantly increase mill time. It is recommended that the largest bit possible is used for each pass.

Bit Material Thickness
1/2 Inch End Mill  

1/2 Inch Ball Nose

1.5 Inch
1/4 Inch End Mill 2.5 Inch
1/4 Inch Ball Nose  

1/8 Inch End Mill

3 Inch
1/8 Inch Ball Nose 3.5 Inch

What is a CNC Router?

A Computer Numeric Control, or “CNC”,  Router is a computer-operated milling machine. The ShopBot has three operational axes and can read 2D and 3D files. It can be used for many different projects that include, but are not limited to:

Milling

Making Molding

 

Furniture Design

How Does the ShopBot CNC Router Work?

The ShopBot CNC Router operates on 3 axes and has a drill bit that takes away material as it moves forwards, backwards, side to side, and up and down around the workspace. A computer software called VCarve Pro is used to control the path that the machine follows while cutting. Different toolpaths can be combined to achieve the best possible finished product. For example, a “roughing” toolpath can be used first to take out the majority of material and leave a rough shape of the final product. Then, a “finishing” tool path can be used to go back over the material to clean up the surfaces and add fine details.

 

Feeds and Speeds

Feed is the linear feed of the tool through the material
Speed is the rotational frequency of the spindle which turns the bit

The feeds and speeds are defined for each bit and material type within the toolpathing software. Feeds and speeds vary for each machine (relative to available spindle power), material type and the environment (temperature, humidity).

Pass Depth and Stepover

The Pass Depth and Stepover indicate how much the bit moves into the material between passes. Introducing too much material at once could cause the bit to break, while too little could create excessive milling time and reduce the life of the bits by dulling them.

Note: Bray’s Vcarve software has tool profiles with pre-assigned Feeds & Speeds, Pass Depths, and Stepovers for all available bits and materials.

movement_diagram.png

More on Milling

The Skinny on End Mills

Flip-Cut (2 Sided Milling) 

Next Steps:

2. Software Setup

3. Machine Setup