Usage and Operation Views: 12

Preventing workpiece rotation or shifting during countersinking: A moving workpiece is a common problem, especially on drill presses and mills: wrong sizes, poor finish, even flying parts. Causes: 1) insufficient clamping force - loose vise or weak fixture; 2) wrong clamp points - weak spots or small contact area; 3) excessive cutting force - high speed, large feed, dull tool: force exceeds clamping; 4) special shapes - round, odd, thin-wall parts are hard to clamp; 5) oily surfaces - low friction, slides; 6) high runout - uneven force pushes the part. Methods: 1) more clamping force - a) tighten the vise with a wrench, not fingers; b) rigid vises, not small worn ones; c) enough force, but not so much that thin parts deform; 2) more friction - a) sandpaper or anti-slip pads between the part and vise jaws; b) wipe oil off; c) serrated (hard) jaws bite in (leave marks - careful on cosmetic parts); 3) right clamp points - a) clamp at rigid, thick spots, not thin walls or cantilevers; b) clamp near the machining area; c) large contact area; 4) dedicated fixtures - a) round parts: V-blocks or round-part fixtures (self-centering); b) odd shapes: custom fixtures; c) thin sheets: vacuum or magnetic chucks (ferrous) beat vises; d) batches: custom fixtures - accurate, reliable, fast; 5) support - a) parallel blocks under the part; b) auxiliary supports at cantilever ends; c) backup pads behind thin walls; 6) less cutting force - a) lower speed; b) smaller feed; c) sharp tools; d) single-flute cuts with less force; 7) locating pins/holes - a) process locating holes with pins against rotation; b) fixtures with locating faces and pins: consistent positioning; 8) clamps and T-bolts - a) large or flat parts: clamp plates + T-bolts are more reliable than vises; b) press on thick spots with equal-height blocks; c) several clamps evenly, not one point; 9) double-sided clamping - a) thin workpieces: clamp both sides so the tool cannot lift the part; b) dedicated double-sided fixtures; 10) first-piece check - a) check for movement after the first part; b) check clamping periodically; c) stop and re-clamp on any movement. Notes by machine: 1) drill press - axial force lifts or spins the part: clamp firmly; small parts in vises, never by hand; 2) mill - high force with side loads: firm vise or clamps, locating pins if needed; 3) machining center - fixtures or vises; pneumatic/hydraulic fixtures preferred; 4) lathe - chuck firmly; slender parts use the tailstock center. Safety: 1) never run without firm clamping - flying parts injure; 2) never hand-hold small parts; 3) on any looseness or shift, stop immediately - do not reach in; 4) stop to clear chips. Clamping is a basic requirement: weak clamping means wrong sizes, poor finish and accidents. Choose the clamping method by shape and size; dedicated fixtures for batches. Our piloted spot facers reduce side force with pilot location - even better with fixtures - ask us.