Bridgeport mill

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This page has details about the Bridgeport milling machine and links to related resources.

Checkout/Training Required

You must be checked out or attend an orientation setting before you will be allowed to use the machine. See Mill_and_Lathe_Training for more detail. The access to the Bridgeport mill will follow special procedures beyond the normal process for certification. Beginners will need to demonstrate ability to safely operate the Mill/Drill before using the Bridgeport.

Specifications

  • Model: Series 1 - J Head
  • Spindle Taper: R8
  • Motor: 1 HP, 1800 RPM, 3 phase, driven by TECO EV series VFD
  • Spindle Speed: 80, 135, 210, 325 660, 1115, 1750, 2720 RPM (@60 hz)
  • Spindle power feed: 0.0015, 0.003, 0.006 inches per revolution
  • Milling capacity: 1.5 Sq In per minute.
  • Table Size: 9" x 42", 3 x 5/8" T-slots on 2.5" centers
  • Quill Travel: 5"
  • Knee Travel: 16"
  • X-Axis Travel: 30"
  • Y-Axis (saddle) Travel: 12"

Resources

  • Bridgeport Manual
  • MIT Machine Shop Videos - This is a blog posting with links to a series of videos made for the MIT Prototyping machine shop that describe how to use machine shop tools including a Milling Machine, Lathe, Grinder, Belt Sander, etc. This is a great series to learn the basics of machining.
  • Milling Speed Calculator - Calculating what spindle speed (RPM) and feed rate to use for various materials can be very complex. This calculator can calculate these values.
  • Mini Mill Tool Kits - This has some good starting values for various materials that can feed into the calculator above to calculate RPM and (maximum) feed rates.
  • For quick reference, The calculations show an RPM of 1910 for aluminium and a feed rate of 15 inches per minute with a 1/2 Endmill. Cutting a full slot at full speed at a depth of 50 mils will be about the maximum the machine could handle at that feed rate (and is probably way to much).
  • Cuts that remove more material create significantly higher forces on the material, which results in less accurate cuts and a poor surface finish.
  • Remember that high RPM create significantly more heat than low RPM. For materials the easily melt or burn such as plastics and wood,