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Induction Check Sheet

Bridgeport Milling Machine

Inductee level of experience with similar machinery:

 

Safety

  • ❌ Do not wear baggy clothing.
  • ✅ Take off any jewellery.
  • 🥽 Wear eye protection at all times.
  • ✅ If you have long sleeves, roll them up.
  • ✅ Tie your hair back appropriately if it is long.
  • ✅ Close the gearbox covers.
  • ❌ Don't reach around the tool while spinning.
  • ❌ Don't leave the chuck key in.
  • ❌ Don't leave the spanner on the draw bar.
  • ✅ Spin the spindle by hand to check it can rotate freely.
  • 🔥 Swarf, your work, and the cutter can get hot.

Materials

  • ✅ Aluminium
  • ✅ Bright drawn mild steel (BDMS)
  • ✅ Stainless steel
  • ✅ Plastics
  • ✅ Brass
  • ✅ Copper
  • ❌ Wood
  • ❌ Fibreglass
  • ❌ Glass

Tooling

  • Milling transfers cutting force axially and radially.
  • Drilling transfers cutting force radially.
  • ✅ Putting a drill in a collet is a good idea.
  • ❌ Don't put a milling cutter in a drill chuck.
  • Tools tend to be High Speed Steel (HSS) or Carbide. Carbide tolerates higher termperatures and is harder, but more brittle.

Milling cutters:

  • End mill.
  • Slot mill. Like end mill but optimised for 180 degree engagement angle.
  • Ball mill.
  • V cutter.
  • Fly cutter.
  • Boring head.

An indexable cutter is a cutter with inserts, usually carbide, that are replaceable.

Materials

  • 💧💧💧 3 pulls on the oil dispenser behind the bed.
  • ✅ The quill should have a layer of oil on it.

Setup

  • Check the machine is set up how you expect:
    • The locks for all 3 axes.
    • The quill feed is engaged/disengaged.
    • The spindle is set to turn in the direction you expect.
    • Your work is clamped securely.

    If you find it set up in a certain way don't assume it's safe.

  • The floor area you are working in is clear of cables, obstacles and potential trip hazards.
  • Ensure there are no obstacles in the travel envelope of the tables.

The list is not exhaustive and it is on the operator to apply common sense.

Work Holding

The wide variety of clamping strategies are one of the things that make the mill so versatile.

  • ❗ The vice jaws and bed are precision ground surfaces that lose precision with damage.
  • ✅ If necessary, clamp sacrificial material around your work to avoid damaaging the vice or bed.

Common clamping strategies:

  • Vice mounted on bed.
  • Clamping kit using T nuts and through bolts.
  • Rotary table.
  • V Blocks.

Main Controls

  • The primary power switch for the machine is a big red rotary switch on the box on the right side. Vertical is on, horizontal is off.
  • Facing the front there's a row of 4 switches. Up is on, down is off. Left to right, they control: spindle, shaper head, auto feed, coolant.
  • The primary power switch for the machine is a big red rotary switch on the box on the right side. Vertical is on, horizontal is off.
  • Spindle direction is set by the switch on the top left of the machine. Left is clockwise, right is counterclickwise, middle is disengaged (looking down).
  • Spindle speed is set by the 3 position pulley gearbox inside the spindle head.

Moving the Bed

  • As you face the machine:
    • The X axis moves left and right.
    • The Y axis moves forwards and backwards.
    • The Z axis moves up and down.
  • Every axis has a lock. You may want to engage the locks to maximise accuracy, as machining forces (usually during heavy machining) can move the axes without user intervention.
  • The X and Y axes are connected to the DRO.
  • The X axis has an autofeed.

Changing Spindle Speed

  • Consult the table on the front of the machine for your desired configuration.
  • Stop the spindle.
  • Set the spindle motor to disengaged by turning the spindle direction switch to middle.
  • Loosen the belt tensioning lock.
  • Move (rotate) the spindle motor to loosen the belt.
  • Move the belt into the desired position.
  • Move (rotate) the motor to tighten the belt.
  • Tighten the belt tensioning lock.
  • Power the spindle, ideally without a tool to ensure it rotates freely and sounds normal.

Changing Tool

  • Stop the spindle.
  • Set the spindle motor to disengaged by turning the spindle direction switch to middle.
  • Using the spindle brake to lock the rotation of the spindle, use a spannner to undo the draw bolt until it is fully unscrewed. You will be able to feel it come free.
  • Using a wooden, plastic, copper or otherwise not hard hammer, gently tap the top of the draw bar to free the tool from the spindle. This will cause the collet (and tool) to fall out. Ensure to support or cushion it appropriately. Brittle tools e.g. carbide can crack from falling short distances onto metal surfaces.
  • Insert a new collet.
  • Tighten the new collet.
  • Set your desired spindle direction.
  • Power the spindle to verify the spindle rotates freely and the machine sounds normal.

Digital Read Out (DRO)

  • The DRO simplifies precision positioning your work relative to the tool.
  • A typical DRO workflow may look like:
    • Jog your tool very slowly until you hear it start to touch your work.
    • For the axis, set the DRO to minus half the tool diameter.
    • Repeat for all axes (so just 2 usually).
    • Jog X and Y to 0.
    • The center of your tool is positioned above the datum of the workpiece.
  • The DRO supports:
    • Metric and Imperial units.
    • Setting an axis to a arbitrary value.
    • Adding or subtracting arbitrary values to the current readout.
    • Polar coordinates.

Rapid Feed

  • Rapid feed can be used to jog the machine quickly, and to ensure a constant feed rate (amd therefore an even surface finish).
  • The controls are:
    • Power: Switch on the front panel. Up is on, down is off.
    • Speed: Rotary dial on the control panel on the right. Speed is logarithmic so don't just crank it to the max.
    • Direction: Left/middle/right lever on the right of the bed.

Quill Feed

  • The quill feed allows the spindle to operated like a pillar drill.
  • During normal machining, the quill feed should be locked using the rotary lever on the front of the machine head.
  • To operate the quill feed, disengage the quill feed lock.
  • Make sure to lock the quill feed after you finish using it.
  • The quill feed has limit nuts that can be adjusted to get a repeatable drill depth.

Cleaning Up

Please ensure you clean and tidy the machine after you finish working.
Ensure that:

  • The main power is off.
  • All the switches on the front panel are off.
  • The bed is free of swarf and debris.
  • There is no tool in the spindle.
  • The autofeed is set to disengaged, i.e. in the middle position.
  • The spindle motor is disengaged via the middle position on the spindle direction switch.
  • The quill feed is retracted and locked.

Terminology Bingo

If you are unaware of these terms, consider searching or asking during your induction.
bed, xyz axis, saddle locks, x axis safety handles, x axis auto feed, auto feed stop, micrometer dials, spindle, quill, drill press feed, slow hand quill feed, auto quill feed, motor, motor tension, motor direction, belt speed, back gears, quill feed ratio, auto quill feed direction, slow feed clutch, motor break, auto quill feed stop, nodding worm and bolts, quill lock, till worm and bolt, spinning the turret, extending the head, DRO, one shot oil system, power controls, vice, rotary table, work clamps, collets, drill chuck, parallels, ends mills, fly cutter, boring head