Planer (metalworking)

• 1. Introduction

  ›

  On a metalworking planer, the blade holds still. It is the metal that moves, clamped to a long driven bed and carried past the cutting edge with each measured stroke. This reversal of the usual arrangement drove industrial metalworking for over a century. Where the machine came from, and why it still shows up in workshops today, are questions that run deeper than they might appear.

• 2. What the Machine Can Do

  ›

  A planer drives the workpiece, not the blade, along the length of its bed. Flat surfaces are the most common product. While grinding achieves greater precision, the planer removes a tremendous amount of metal in a single pass while holding high accuracy. Keyways, the narrow slots that lock a rotating component to its shaft, are another routine task. A planer fitted with a boring-bar type tool can enter a drilled or cored hole and cut internal features that milling and boring cannot produce. Those features include irregularly shaped holes with tight corners, work that wire EDM now handles in some cases. A further capability comes from coupling the table's linear motion to simultaneous rotation, which produces a helical toolpath rather than a straight line. That technique is related to both helical milling and single-point screw cutting.

• 3. A Disputed Birth

  ›

  Early planing ideas were already underway in France in the 1750s. The machine took its recognizable modern form in the late 1810s, when several British pioneers working in separate shops arrived at roughly the same solution. James Fox, George Rennie, Matthew Murray, Joseph Clement, and Richard Roberts each contributed to that development, but their work went largely undocumented. Proprietary secrecy kept some details hidden; the simple absence of anyone writing for posterity accounts for the rest. Roe, writing in 1916, assembled the most complete account then available. He acknowledged that the full story would probably never be known, and no argument since has settled the question of precedence.

• 4. Two Designs

  ›

  A double-housing planer places vertical supports along both sides of its long bed. The open-side variety carries a support on only one side, which allows the workpiece to extend past the bed's edge. That extra clearance makes the open-side design useful for oversized or irregularly shaped material. In scale, metal planers range from a table size of 30 inches by 72 inches to 20 feet by 62 feet. In weight, they range from around 20,000 pounds to more than a million. The open-side configuration becomes practically necessary at that upper end, since a closed frame would limit what material could be brought to the blade.

• 5. Slow Fade, Long Tail

  ›

  Milling machines, broaching machines, and grinding machines have largely claimed the work that once defined the planer's role. Planers and shapers are now classified as obsolescent. Yet they have not left the metalworking world entirely. Smaller tool and die shops inside larger production facilities still run them to maintain and repair large stamping dies and plastic injection molds. They also serve shops where an unusually large block of metal, typically four feet by eight feet or more, must be squared. That task arises when a horizontal grinder or floor mill is unavailable, too expensive, or impractical. An old machine already on hand and long since paid for holds a strong cost advantage over any newer purchase. That principle explains why industrial techniques tend toward a long gradual obsolescence rather than the sharp drop-off typical of mass-consumer technology. A planer that still cuts straight and costs nothing to own will keep cutting.