student_shop:class3-4 [School of Physics and Astronomy Wiki]

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====== Sessions 3 & 4 ======

===== Vertical Milling Machine =====

==== Safety ====

  - Always wear safety glasses.
  - Work piece must be clamped securely in a vice or to the mill table.
  - Make sure you are using the proper speeds and feeds for the material and cutter size.  Make sure you understand how to switch from high to low range and how to change the v belt on step pulleys.
  - Do not use dull or burned cutting tools.
  - Once tool is clamped into the collet remove drawbar wrench immediately.  Do not leave wrench on drawbar nut.
  - Make sure spindle is running in the proper direction.  Cutters are right hand.  Spindle must rotate clockwise when viewed form the top of machine.
  - Make sure cutter is clear of part, vice, and your hands before starting spindle.
  - Always stay at the machine when it is running.
  - Make sure cutter is a safe distance away from part when using power feed.      
  - Make sure machine has fully stopped before making any measurements, adjustments, or removing part.  After spindle is turned off use the brake to stop the spindle.
  - When removing a tool from the spindle fold up a rag and put it on the table under the tool.  Hold the brake and loosen the drawbar nut with the wrench 1/2 to 1 turn. Hold the tool with one hand and hit the nut with the brass part of the wrench.
  - Once machine is off and tool is removed clean machine with a brush, compressed air, then wipe off with a rag. 

==== Videos: Milling Machines and Cutters & Machining Operations for Vertical Milling Machine ====

  - Parts of mill (handout)
  - Changing speeds and Hi to Lo range
  - Tool holding
  - Drill chucks
  - Collets - Bridgeport mill R-8 
  - Workholding
    * Vice - mounting and aligning
    * Rotary table - indicate center
    * Indexing head - indicate center
    * Clamping to table
  - Cutting Speeds & Feeds
    * Aluminum	150 SFM (surface feet per minute)
    * Brass 150 SFM
    * Copper 100 SFM
    * Stainless Steel 30 SFM
    * Steel  50 SFM
    * RPM = (4 x cutting speed) / Diameter of cutter
    * Example: At what speed should a 1/2" end mill revolve to cut a piece of aluminum?
      * RPM= 4 x 150 SFM
      * 0.5" dia.
      * RPM= 1200
    * Feeds -
      * IPM (inches per minute)
      * Depends upon cutter diameter, material, design of cutter, depth and width of cut, type of finish and accuracy
      * Feed = no. of teeth x feed per tooth x RPM
  - Operations 
    * Edge Finding and Indicating
    * Drilling, Reaming, Counterboring, Countersinking
    * Facing of Top Surface/Procedure for squaring up a block
    * Facing of the end or side of part - use side of end mill Climb vs. Conventional (safer) milling - handout
    * Slotting
    * Boring-for precision holes, odd diameters
    * Special Cutters
      - Ball end mills
      - Slitting Saws
      - Key seat cutters
      - Dovetail cutters

===== Horizontal Milling Machine =====

Use for working on ends of long or tall parts

===== Procedure for squaring up aluminum stock =====

  - Saw stock ~1/8" oversize
  - Deburr edges
  - Clamp on parallels in mill vice with factory edges against vie jaws.  Tap down after clamping.
  - Carefully touch off, depth of cut .02"-.05", feed rate ~2 IPM.  Mill edge until it just cleans up using side of mill cutter. **Conventional Cut**.
  - Remove from vice, deburr, clean vice, turn 180 degrees & tighten to vice. Touch off, take minimum cut, measure part, set DRO, and take finish cut to final dimension. Take .10" -.02" finish cut. Climb Cut.
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