2.5 mm Drilling Head

U-STAR 2.5 mm modeling drill bit

A drill bit 2.5 mm in diameter is among the heavier ones on a modeling bench. It is not used as often as the tenths and the one-millimeter diameters, but when it is needed nothing replaces it: opening a hole out gradually in smaller steps is tedious and the result tends to come out oval. It is clamped in a pin vise or in a mini drill.

Where a diameter of 2.5 mm suits

Typically in larger scales and on vehicles. Holes for heavier brass tubing, the mouths of exhausts and barrels, ways through for wheel axles, holes in bases and in the groundwork of dioramas through which a wire or a pin is passed. It is also used to lighten solid parts, when a hollow is meant to be sensed behind a shape, and for repairs, when a hole has to be enlarged in one go and without a series of intermediate steps.

How to work with it

• Pilot drill with a thinner bit; a heavy drill finds its mark less well in plastic freehand.
• Drill at right angles and without pressure, otherwise the plastic around the hole is drawn out into a white ring.
• Keep withdrawing it and clearing the swarf from the flutes; with larger diameters there is plenty of it.
• Always clamp or firmly support the part; at this diameter the torque is already noticeable.
• Level the edge of the hole with a knife or with a coarser drill turned between the fingers.
• Before you buy, check that the diameter of the shank will fit into your chuck.

Who it is for

For modelers who build in larger scales, who modify parts or who are preparing bases and dioramas. This is a tool, not a kit or an accessory for a particular model.