What to measure
Two measurements decide this jig. The first is the offset: the distance from the edge of the board to the centre of the hole. For pilot holes that fix a panel to the edge of another board, the offset is half the thickness of that other board, so 9 mm for an 18 mm carcass side; this page uses 10 mm as a round starting value. The second is the thickness of the board the jig will sit on. The fence hangs down over its edge and must be shorter than the board is thick, or the jig rocks on the bench. The 10 mm fence here suits boards of 12 mm and up.
Hole clearance, thickness and material
Measure the drill bit itself, on the smooth shank. The guide hole is the bit diameter plus about 0.2 mm, so 3.2 mm for a 3 mm bit. Small vertical holes print a little undersize; if the bit does not turn freely between your fingers in the printed hole, go to 3.3 mm. Do not ream the hole out with the drill at full speed, as that melts the plastic and leaves it oversize. The block is 8 mm thick, more than twice the bit diameter, which is enough length to stop a thin bit from skating. PLA is a good choice for jigs because it is stiff and holds its dimensions; PETG is slightly more forgiving of heat from the bit.
Printing
Print the jig as generated, block flat on the bed with the fence pointing up. No supports are needed, and the guide hole is vertical, which is the orientation that prints round. Use a 0.2 mm layer height and at least four perimeters so the hole is surrounded by solid plastic, not infill. The whole jig is 60 by 40 by 18 mm.
Using it
Turn the jig over, lay the block on the face of the board, push the fence against the edge and clamp it. Mark where along the edge each hole goes and line the mark up with the centre of the jig; the hole is centred in the 60 mm length. A 3 mm bit is easy to snap: drill in short pecks, clear the chips, and wear eye protection. A plain printed hole wears, so reprint the jig when the bit starts to feel loose in it.
Outline drawing
To scale. Left: top view as printed, fence along the top edge. Right: end view, block 8 mm thick with the fence rising 10 mm above it.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | drill_jig |
| Jig length along the edge (X) | length | 60 |
| Jig width including the fence (Y) | width | 40 |
| Block thickness | thickness | 8 |
| Guide hole diameter | hole_diameter | 3.2 |
| Hole centre to workpiece edge | offset | 10 |
| Hole position along the length (0 centres it) | hole_position | 0 |
| Fence thickness | fence_thickness | 5 |
| Fence height | fence_height | 10 |
All lengths are in millimetres. Outer size from these values: 60 x 40 x 18 mm.
Open the generator with these values
This model needs the $7 licence key: one payment, one key, and it opens all five paid models. Get a licence key on Gumroad ($7)
The drill guide jig needs a licence key: without one the generator shows the model locked, lists the values from this link and fills them in as soon as you unlock. The fitted drawer organiser bin is the free model and downloads with no key.