Quick answer

Use a pin vise for any hole smaller than about 1mm, and let the bit cut at low speed with light pressure. Mark the center with a pin or scribe, chuck the bit so only the flutes show, and clear chips every few turns. The Tamiya Fine Pin Vise S holds bits from 0.1mm to 1.0mm, which covers most detail holes on 1/100 and 1/144 kits.

Pick the right bit for the hole you actually need

Pin vise bits are measured by shank and cutting diameter, and the two are not the same. A 0.5mm bit cuts a 0.5mm hole but may have a thicker shank that will not fit a small chuck. Check the shank against your vise's range before you buy a set. For model kit detailing, a spread of 0.3mm, 0.5mm, 0.8mm, and 1.0mm covers most vents, bolt heads, and pin replacements. If you only need one size, match it to the rod or wire you plan to insert, not to the look of the hole.

Mark the hole before the bit touches plastic

A pin vise will wander on a smooth surface. Press a sewing pin, a scribe, or the back of a knife blade into the plastic to make a small dimple. On curved surfaces like a shoulder or calf armor, angle the dimple so it faces the direction you want to drill. If the dimple is off-center, fill it with a tiny drop of thin cement and re-mark after it cures. This one step prevents most broken bits and oval holes.

Chuck the bit so only the flutes are exposed

Insert the bit until it bottoms out, then pull it back about 1mm so the jaws grip the smooth shank rather than the flutes. Tighten the chuck firmly by hand. If the bit wobbles when you spin the vise, it is not centered; loosen, rotate the bit a quarter turn, and retighten. A wobbly bit cuts an oversized hole and snaps easily. Keep the rotating end of the vise against your palm so the tool turns smoothly instead of fighting your wrist.

Drill at low speed with light, even pressure

Turn the vise slowly and let the flutes do the cutting. Pressing hard generates heat, and heat softens polystyrene, which makes the bit grab and crack the part. Drill in short bursts: a few turns, then reverse a half turn to break the chip, then continue. Support thin or hollow parts from behind with a piece of scrap runner or a wooden block. If you feel the bit bite suddenly, stop and clear the flutes before continuing.

Clean the hole and test-fit before you commit

After drilling, run the bit through the hole by hand to clear dust, then test-fit your rod, wire, or pin. If the fit is tight, enlarge the hole with the next bit size rather than forcing the rod, which can split the plastic. For pinning joints, drill slightly deeper than the pin length so trapped air and glue have somewhere to go. A clean, slightly loose fit holds better with cement than a forced one.

Pin vise drilling steps

  1. Mark the center point: Press a pin or scribe into the plastic to create a dimple. On curved armor, angle the dimple toward the intended drill direction. Checkpoint: the dimple should hold the bit tip without sliding.
  2. Select and check the bit: Match the bit diameter to the rod or wire you will insert. Confirm the shank fits your vise's chuck range before tightening. Mistake to avoid: using a bit whose shank is too thick for the chuck, which prevents proper grip.
  3. Chuck the bit with flutes exposed: Insert the bit fully, pull back about 1mm, and tighten by hand. Spin the vise to check for wobble and adjust if needed. Checkpoint: no visible wobble when the vise spins.
  4. Drill in short bursts: Turn slowly with light pressure. Reverse a half turn every few turns to break chips. Support thin parts from behind. Mistake to avoid: pressing hard and fast, which heats the plastic and can crack the part.
  5. Clear chips and test-fit: Run the bit through by hand to remove dust. Test-fit the rod or pin; enlarge with the next bit size if tight. Next step: if the fit is loose, use a thicker rod or add a drop of thin cement when installing.

Tools that match this process

  • Tamiya Fine Pin Vise S (0.1～1.0mm) (74051): Tamiya Fine Pin Vise S (0.1~1.0mm) (74051) has a rotating end and holds drill bits from 0.1mm to 1.0mm in diameter. The rotating end keeps the tool steady in your palm, and the 0.1-1.0mm range covers the small detail holes most modelers drill. Note that Tamiya item 74134 is not compatible with this vise.
  • G-Rework Decal - RE/100 XM-02 Den'an-Gei Use: G-Rework Decal - RE/100 XM-02 Den'an-Gei Use is a waterslide decal designed for the RE/100 XM-02 Den'an-Gei. Decals are a common reason to drill small holes, such as for vent or sensor details that sit under or beside marking placement. Plan those holes before you apply decals so you are not drilling near finished markings.