The One and Only Problem Set

Modeling Precision Machines

Value: 10% of your grade


The goal of this problem set is for you to learn how to model the accuracy of a machine by modeling an actual machine. Once you understand how to model the accuracy of a machine, you will be able to better design precision machines.

The Subject

The subject that each person will model is a Bridgeport milling machine.


  1. Create a hand sketch of the machine
  2. Create a first-order-solid model (no detail that is not needed to represent the kinematics of operation!)
  3. Create a stick figure showing the structural loop and coordinate systems at each center-of-stiffness for each major element's interface
  4. Show the solid model of each major element and clearly indicate each elements' coordinate system location
  5. Create a spreadsheet or Matlab script to determine the three translational and three rotational errors present in each axis. Make estimates of the repeatability and accuracy of each axes major elements
  6. Complete the ErrorGainSpreadsheet, which is downloadable from the website, and give your final estimate of the repeatability and accuracy of the machine for its sweet spot and at its extreme range of travel


Create a power point presentation to present your models and predictions. This presentation MUST be turned in as a paper copy and as electronic media so they can be posted on the course web site (no hyperlinks to your site... these are too easily broken). This presentation should make it clear to any competent engineer (or perspective employer) that you know how to model a precision machine.