The table below contains both html and Power Point versions of the presentations on various aspects of the MiniMill™. There two basic versions of the MiniMill™. The Standard MiniMill™ which is driven by Ball Screws and Linear Rails. The Modified MiniMill™, which is driven by linear motors and air bearings.  Both machines use our patented two "L" design to keep manufacturing cost down.

html	power point file	size of ppt	Descriptions
	axtrusion.ppt	0.7 megs	A description of the Axtrusion™. The Axtrusion™ is a new linear motion building block which combines linear motors and air bearings.
	standard_minimill.ppt	1.3 megs	The Standard MiniMill™ is a small, high accuracy machining center.   It is driven by standard component motion components.  I.E. Ball Screws and Linear Rails.
	modified_minimill.ppt	1.3 megs	The Modified MiniMill™ is almost identical to the Standard MiniMill™.  However, It is uses the Axtrusion concept to provide its motion.
	standard_minimill_stiffness.ppt	1.0 megs	The stiffness calculations for the Standard MiniMill™
	modified_minimill_stiffness.ppt	1.3 megs	The stiffness calculations for the Modified MiniMill™
	tool_stiffness.ppt	0.2 megs	Stiffness calculations for the end-mills.  This serves as a comparison to put the stiffness numbers of the Milling machines in perspective.
	minimill_costs.ppt	0.9 megs	Cost Estimates for both the Standard and Modified MiniMills™

Machine Overview:

Note: This is not am image of the latest design iteration.   Protective shroud not shown.

This a concept and initial design for a low-cost, high accuracy desktop milling machine.

The functional requirements (FR's) of the machine are:

• Accuracy of at least 25.5 mm (0.001 inches)
• A Work Volume of 300 mm^3 (11.8 inches)
• 6 kW (8 hp) Cutting Power
• Maximum of 10,000 to 20,000 RPM
• Three axis CNC control.
• Low Cost (initial estimates of $10K-$15K)

Once the FR's were defined and a rough machine concept chosen an error budget had to be generated to provide at target for each component to be designed to.

Key Machine Components:

This milling machine requires the development of two key areas; the spindle, and the sliding ways.  Below are basic summaries of each.  Go to the more detailed write ups for their design parameters, performance calculations, error calculations, and other information.

The Axtrusion (a.k.a the sliding ways):

Each Axtrusion Assembly is made up of a Way and Carriage.  The Way is a block of Granite or Aluminum with a permanent magnet track, for a linear motor, glued into an angled groove.  The Carriage Assembly contains the coils of the linear motor and six porous graphite air bearings. There is very strong attractive force between the linear motor magnets (on the way) and the coils (on the carriage).  By angling the linear motor we can use this attractive force to preload the air bearings onto the way.   The amount of preload on each bearing is specified by the angle and the location of the linear motor.

The figures below show the Axtrusion Assembly used in the in the X direction on the Mini-Mill.  See the Detailed Axtrusion write-up for the combined Y and Z Axtrusion Assembly, stiffness calculation, error analysis, and other more detailed information on the Axtrusion.