Intro Drilling and Milling (Die Project)

Tools

  • 1/2″ x 1-5/8″ square end mill
  • 3/8″ twist drill
  • center drill
  • edge finder
  • caliper
  • chip brush
  • rag

Parts

  • 1″ x 1″ x 1″ aluminum bar stock

Training Goals

  • Learn to operate the 3-axis mill in manual (DRO) mode
  • Understand major safety aspects of mill operation
  • Begin to build machining vocabulary
  • Set up and perform the following operations:
  • Endmilling
  • Drilling
  • Begin to understand depth of cut and spindle speed
  • If you need to make more complicated cuts, or are uncomfortable in any way, ask a mentor!

Milling Machine Specific Safety

  • Endmills are sharp, handle with care. They are also fragile, try not to drop them.
  • Double check your PPE (personal protective equipment)
    • Long hair in a bun
    • No long loose clothing, sleeves rolled up
    • Jewelry removed (or taped)
  • Cleaning: use compressed air, vacuums, and brushes to clean the mill until the next user could not tell what material you were cutting.

Familiarize yourself with the CNC milling machine

  • Familiarize yourself with the parts of the CNC Mill.
  • Emergency Stop Button
  • Spindle
  • Quill Lever and Quill Lock
  • X-axis handwheel, Y-axis handwheel
  • Table
  • Drawbar In/Out buttons
  • Spindle Power Switch

Intro to the milling machine

  • SHOW: sample parts cut on the milling machine
  • TELL:
    • Materials it can cut: plastics, metals
    • NO: wood
    • Tolerance: 0.010″ to 0.0005″ depending on setup
    • Part size: typically 1cm to 30cm (1/2″ to 12″)

Walk through drawing and steps

  • SHOW: drawing, stock, tools

Introduce Control

  • STUDENTS DO:
    • Release e-stop
    • Mode
    • DRO
    • Zero X & Y

Axes of Motion

  • Explain X and Y
  • STUDENTS DO: Move X in coarse mode and fine mode to see the difference
  • TELL: Always use fine mode when a tool is near a part
  • STUDENTS DO: Move Z with Jog Mode
  • ALWAYS IMMEDIATELY EXIT Jog Mode

Spindle Speed

  • TELL: define spindle speed and feed rate
  • Ideal speed and feed based on tool and material
  • STUDENTS DO: set spindle speed

DRO

  • Read the DRO
  • How to zero the axes or set them to a value

Load Stock in Vise

  • Use Parallels
  • Keep everything clean
  • Use minimum practical extension above vise
  • Off-center part holding is not ideal
  • DEMO: tapping part down while tightening, check parallels, then undo vise

Tooling: Endmills

  • SHOW: 1/2″ endmill, made to cut on the sides and the end

Load tooling in spindle

  • DEMO: Installing 1/2″ EM in spindle
  • wipe collet and spindle taper with finger
  • quill up
  • quill locked
  • tap IN button briefly until collet begins to grab
  • hold tool and press IN button until fully inserted and air sound is slower

Depth of Cut

  • DRAW: define axial depth of cut
  • DRAW: define radial depth of cut
  • We’re taking a large axial depth of cut here so we’ll take a small radial depth of cut

Setup 1: Endmilling

  • Set up stock sticking out of right side of vise, on parallels
  • Set up 1/2″ end mill and set spindle speed
  • Take a tiny bit of stock off the end, in two axial (vertical) passes
  • Flip stock 180 degrees to machine opposite side
  • Take a tiny bit off–only move the end mill out of the way in Y!
  • Measure (leave in vise)
  • Set X DRO to measurement of piece
  • Shave off .020″ to .030″ until part measures 0.900 +/- .015″. Repeat until all six side are machined.

Step 1: Enhancements

  • Use the vise stop and DRO to accelerate the process

Edgefinding

  • STUDENTS DO: Load appropriate collet and edgefinder
  • STUDENTS DO: Set spindle speed 1200 RPM
  • TELL: discuss edgefinding process and tool radius (.100″)
  • DEMO: Finding X zero with edgefinder and setting DRO
  • STUDENTS DO: find X and Y zero (back left of die)

Tooling: Drills

  • SHOW: Drill types
  • Twist Drill
  • Center Drill
  • Other types exist
  • Vertical holes on flat surfaces only
  • SHOW: drill locations in tooling drawers

Drill holes

  • STUDENTS DO: Load drill chuck
  • DO NOT Let go of chuck key while in chuck
  • DEMO: drill “1” side
    • Insert drill bit
    • Go to location
    • Center Drill
    • Drill .100″ (+.025″ / -.000″) deep with 3/8″ bit
    • Demonstrate peck drilling (1/4″ pecks after 1/2″ deep)
    • Peck drill .910″ deep
    • Use lubricant
  • STUDENTS DO: repeat for all holes

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