Make Something Big (Overview)
Assignment
The assignment for this week is to "make something big" out of plywood or foam.
Providence Materials
You will each be given one sheet of 4' x 8' of 23/32"poplar plywood to cut on the ShopBot which is recommended for 2D designs. There will also be a few sheets of foam which we can laminate to make 3D designs.
Always measure the thickness of your material with calipers. Do not assume that your material is the same exact thickness as specified.
Shopbot Specs
- What is a ShopBot?
- A ShopBot is a large CNC router that uses a bit (like the Modela) to cut files.
- Subtractive process.
- At AS220 Labs we have a ShopBot PRSstandard96
- The bed size of the ShopBot at AS220 Labs is 4' x 8' (or 48" x 96").
- 4' feet of travel in the X axis
- 8' of travel in the Y axis.
- 6" of travel on the Z axis (with a one inch bit inserted)
- 2 collet sizes: 1/4", 1/2"
General Guidelines
Rules of Thumb
- When designing your file, make sure to leave at least an inch around the margins of your material. We will need to screw the material down to the bed of the ShopBot and we do not want the bit on the machine to hit the screws.
- Tool clearance between parts is determined by the thickness of the bit used.
- Depth of a cut in any one pass is 1/2 the diameter of the bit used
File Formats
- 2D designs:
- Inkscape: save as a PDF
- All other drawing programs: PDF, DXF or Ai are acceptable.
- 3D designs: save as a STL
Feeds and Speeds
Plywood
Spindle Speed = 12,000 - 14,000 RPM
Feed Rate = 3.0 inches per second
Plunge Rate = 1.5 inches per second
Foam
Spindle Speed = 15,000 RPM
Feed Rate = 4.0 inches per second
Plunge Rate = 2.0 inches per second
Upcut bits vs Downcut
http://www.newwoodworker.com/updowncutbits.html
2D Designs
You can use 2 dimensional design software to create files for the ShopBot the same way you created files to cut on the lasercutter. You can use any of the software we have used so far, (Inkscape), or any other software you choose.
2D designs must be saved / exported as file as a .PDF file type from Inkscape. If you are using another CAD package, DXF or PDF or Ai.
Later, then we can import your design into PartWorks to create files that we can cut on the ShopBot.
Plywood
This is a plywood press-fit side table that makes use of both pocket and profile cuts in a 2D file.
Pocket Cuts vs Profile Cuts
- Pocket Cuts: The lines that are etched into the table, but do not cut all the way through are "pocket cuts".
- Profile Cuts: The outline of the table top, where it is cut out around the outside edge is a "profile cut".
Plywood Side Table Example - Raw Wood
Plywood Side Table Example - Finished Wood
3D Designs
You can also use the 3D design software we covered in the clsss (or any other software you choose). Three dimensional designs take much longer to cut than 2D designs.
3D designs must be exported as a .stl file format.
Foam
Foam is much faster to cut than wood because it offers very little resistance, we can run the machine at full speed without breaking a bit.. If you want to do a 3D design, foam is recommended.
