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CNC Guide

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

Contact the Makerspaces

Library 21c: 
    (719) 531-6333 x1549

East Library: 
    (719) 531-6333  x1372

Sand Creek Library: 
    (719) 531-6333 x7018

Manitou Springs Library: 
    (719) 531-6333 x7004

The Machine

Model ShopBot Desktop
Bed Size 24" x 18"
Max Material Thickness 2" (the actual usable thickness will depend on the bit)


What is a Bit?

Terms to Know:

  • Cut Diameter - The diameter of the tip used for the cut, which determines the minimum width of a cut line. Smaller cut diameters allow for more detailed work, but take longer to cut the same area than a larger bit. Standard cut diameters range from 1/2" to 1/16", however more are available.
  • Length of Cut (LoC) - The length of the bit from tip to the end of the flutes, which determines the maximum depth of the cut. Generally, the larger the cut diameter, the larger possible LoC.
  • Flutes - The bladed grooves that run along the length of cut (LoC). The more flutes a bit has, the more material that can be removed at once, allowing for faster cut speeds. The cutting blades come in a variety of shapes that determine how the material is moved during the cut.
    • Straight - The flutes run in a straight line down the LoC. Theses bits are generally cheaper, but have a limit to how deep a pass can be when cutting.
    • Up, Down, or Compression - For spiral bits, this determines the direction the blades face as they run along the spiraled flute. Up-cuts move the debris upward, leaving a smooth bottom of the cut, while the top is rougher. The opposite is true for down-cuts. Compression flutes move the material towards the middle and can often leave the material smooth on both ends.
  • Shank and Shank Diameter - The part of the bit that goes into the spindle, which may have a significantly different diameter than the cut diameter. Most bits supplied by PPLD have 1/4" shanks, however the are also bits with 1/8" and 1/2" shanks.
  • End - The shape of the tip of the bit.
    • Endmill - The end is flat, leaving the edges of a cut that does not go through the material at 90 degrees.
    • Ballnose - The end is rounded, leaving the edges curved like a bowl.
    • Engraving - A sharped tip that is half the cut diameter, and often used for fine detail and lettering.
    • V-Bit - A bit used for using with V-Carve toolpaths for lettering.

PPLD Supplied Bits

These are the bits supplied by PPLD. If you would like to use your own bits, you can as long as they are compatible with ShopBot routers. If you do supply your own bits, you will have to manually add them to the tool library in VCarve Pro.

PPLD Bits:

All bits have an 1/4" shank and two flutes unless noted.

Bit Number Picture
1" V-Bit 90° (1/2" shank) 37-63
1 V-Bit 60° (1/2" shank) 37-82
1/2" V-Bit 90° 37-61
1/2" Straight End Mill 48-014
1/2" Straight End Mill (1/2" shank) 48-080
1/4" Straight End Mill (1/2" shank) 48-018
1/4" Down-cut 57-910
1/4" Up-cut End Mill 1 Flute 65-023
1/4" Engraving 0.02" tip 37-05
1/4" Compression End Mill 60-112
1/8" Up-cut Ballnose 52-240B
1/8" Down-cut End Mill 57-240
1/16" Up-cut Ballnose PCL 583659
1/16" Up-cut End Mill 1 Flute (1/8" shank) 65-000