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Using the CNC Router

General Safety Note: Under NO circumstances should a student open any casing of any of the CNC tools or other related equipment in the Technology Lab or Build Lab. Please notify Lab or Shop staff if any issues outside of this guide should arise.

Step-by-step 2D file walkthrough: 2D Routing Guide

Step-by-step 3D file walkthrough: 3D Routing Guide

Bits and Speeds reference chart: Bits and Speeds

Step-by-step CNC Router setup: Using the CNC

The school has a Shopbot CNC Router with a 96” (x-dimension) by 60" (y-dimension) bed. The CNC Router is located in the Design Lab in Goldsmith Hall 1.108.

CNC Routing Hours

The CNC Router is available during normal Design Support Lab hours, and end mills (bits) are available for purchase at the Technology Lab service desk during its regular hours.


Students must supply their own materials and buy their own bits. Bring your files on a USB memory stick. Copy files to the computer desktop. Your files must use the template discussed below.

Acceptable Materials
  • Foam - all kinds, EPS is preferred because it can be recycled
  • Wood - Plywood is preferable to solid wood because of warping
  • Formaldehyde-Free MDF (1" Maximum thickness per operation.)
  • Acrylic & other sheet plastics
  • Aluminum
Prohibited Materials
  • MDF - Any thicker than 1" and all non-Formaldehyde-Free
  • Metals other than aluminum
  • Cement board, Rockite, plaster, etc. (anything containing Portland cement)
  • Ask first about anything not on either list
Local material sources:


  • SOA Computer Lab Service Desk, SUT 1.102.  Carries 4'x4' blocks of high-density insulating foam in 2" ($30) and 3" ($40) thicknesses.
  • Polyplastics, 10201 Metropolitan Dr.  Austin, TX 78758 512-339-9293
  • Austin Custom Foam, 1515 Dungan Lane,  Austin, TX 78754  512-834-3626
  • Austin Fine Lumber & Plywood - 9407 Brown Ln  Austin, TX 78754, (512) 836-8990
  • Home Depot - 1200 Barbara Jordan Boulevard Austin, TX 78723, (512) 703-4110
  • Lowe's - 8000 Shoal Creek Blvd, Austin, TX 78757, (512) 634-4330
Material Guidelines:

minimum 12” x 12” and maximum 60” x 96”

Machining Limitations:
  • Vertical Projection - Since our CNC router is 3-axis, it cannot perform undercuts (i.e. the router bit is always vertical).  This means that any surface file will be cut as a top-down vertical projection of the overall file.
  • Machine Fillets - Since all router bits are round, all interior angle cuts will be filleted to the radius of the router bit by the router as it cuts.  Although it is not necessary to represent these fillets in your drawings, it can often be helpful to do so in order to evaluate the composition of your object before you make it.
  • Cut Length - The general rule for the CNC Router is that the thickness of your material cannot exceed the cut length of the router bit your are using.  It is a best practice to select your desired router bit and record its cut length early in your process so that you can include this limitation as a design constraint.  This limitation should not be understood as limiting the overall depth or size of your finished product, it simply dictates when you can laminate before cutting and when you have to laminate after cutting.
  • Accuracy - The ShopBot CNC is accurate down to the thousands of an inch in both precision and repeatability. In order for your measurements of material thickness to be accurate enough for our CNC process you MUST MEASURE YOUR ACTUAL MATERIAL THICKNESS WITH CALIPERS and use this number in your CNC files.
Training breaks down into three parts:

i. 2D software (profiles and pockets)

ii. 3D software (surfaces)

iii. machine interface in woodshop 

Next: 2D Routing Guide

         3D Routing Guide

         Bits and Speeds

         Using the CNC

CNC Policies

  • In addition to the Design Support Lab's safety training, operators must first complete CNC Router training and certification. In order to use the CNC the student, faculty, or staff must (1) have gone through a CNC training session (2) been certified/working with Ben or Eric (3) paid the subscription fee for the semester and (4) purchased the correct end mills for their project.
  • If you notice that the CNC requires cleaning or maintenance, please notify the Technology Desk at 471-1189 immediately.
  • Operating the CNC router in any unsafe way can result in revoking of privileges.
  • Operating the CNC router without the appropriate training can result in revoking of privileges.
  • Operating the CNC router with another person's login can result in revoking of privileges for you and for the person who allowed you access to the system.
  • CNC subscriptions are non-transferable, the person listed on the subscription must be present during the operation of the CNC. The applies to group projects. The person logged into the computer is the person who is officially responsible for the CNC during its use.
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