Drill over a 2.5mm hole and cut an M3 thread

3D printed holes might be smaller than designed or not very accurate. It is useful to drill over the holes to make them fit the screws or prepare them for cutting a thread.

Get a 2.5 mm drill bit. Check the drill with a caliper to make sure it is the correct size. 2.5 mm is the recommended hole diameter for cutting a M3 thread.
Drill the holes
- (Option 1) Using drill press:
  1. Attach the drill bit into the chuck of the drill press. Make sure that the drill bit is centered.
  2. Clamp your 3D printed piece into the vice.
  3. Place the vice under the drill.
  4. Make sure that the drill bit can go far enough to drill through the part.
  5. Raise the drill press plate if necessary.
  6. Drill through the holes of the part.
- (Option 2) Using cordless drill:
  1. Attach the drill bit into the chuck of a cordless drill.
  2. Hold the piece with your hand. You can hold it flat on the edge of the table.
  3. Drill the holes.
Cut a thread into the holes.
- (Option 1) By hand:
  1. Get a M3 tap (will be given by instructor).
  2. Attach the tap to the tap wrench.
  3. Center the tap to the hole.
  4. Start turning the tap into the hole clockwise.
  5. Try to keep the tap straight with the hole.
  6. Tap through the hole.
  7. Bring the tap out by turning it counter-clockwise.
- (Option 2) With cordless drill:
  1. Attach M3 tap into the chuck of the cordless drill.
  2. Set cordless drill clutch to the lowest torque setting (increase the torque setting if the lowest is too weak). Low torque setting helps to prevent destroying the thread by over-torquing it.
  3. Set cordless drill speed to 1 (the lowest speed) for better speed control.
  4. Make sure that the drill rotates clockwise.
  5. Clamp the piece into a vice or hold it flat on the table by hand.
  6. Try to keep the tap straight with the hole.
  7. Tap through the hole.
  8. Bring the tap out by setting the drill to rotate counter-clockwise.