What to measure
For dowel joints the two halves of the joint must agree, so measure once and use the same jig for both parts. Measure the dowels first: 6 mm dowels vary from about 5.8 to 6.2 mm depending on the wood and how dry it is, and the bit should match the dowel, not the label. Then set the offset, the distance from the reference edge to the hole centre. This page uses 20 mm, a common position for a dowel in the face of a panel that meets another at a corner. Measure the offset on your own drawing or on the mating part and type that number.
Hole clearance, thickness and material
The guide hole is 6.2 mm for a 6 mm bit. For dowel work the hole position matters more than in pilot drilling, since half a millimetre of slop is a visible step in the joint, so do not go looser than 6.3 mm. The block is 12 mm thick: a dowel hole has to be square to the face, and a guide length of twice the bit diameter keeps a hand drill from leaning. PLA is preferred for its stiffness. For more than a few dozen holes, set the guide hole to the outside diameter of a metal drill bushing instead and press the bushing in; printed plastic wears oval.
Printing
Print flat, fence up, no supports. Use a 0.2 mm layer height, five perimeters and 40 percent infill so the block does not crush under a clamp. The part is 80 by 50 by 24 mm. Check the printed offset with a caliper before use: measure from the inner face of the fence to the near side of the hole and add half the hole diameter.
Pairs of holes
The hole is centred along the 80 mm length here. To drill two dowel holes a fixed distance apart, set the hole position to a value such as 20, which puts the hole 20 mm from the left end, then butt that end against a stop or the corner of the panel. Use the same end of the jig against the matching corner on the mating part, so the two holes line up. Clamp the jig for every hole and wear eye protection.
Outline drawing
To scale. Left: top view as printed, fence along the top edge. Right: end view, block 12 mm thick with the fence rising 12 mm above it.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | drill_jig |
| Jig length along the edge (X) | length | 80 |
| Jig width including the fence (Y) | width | 50 |
| Block thickness | thickness | 12 |
| Guide hole diameter | hole_diameter | 6.2 |
| Hole centre to workpiece edge | offset | 20 |
| Hole position along the length (0 centres it) | hole_position | 0 |
| Fence thickness | fence_thickness | 6 |
| Fence height | fence_height | 12 |
All lengths are in millimetres. Outer size from these values: 80 x 50 x 24 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.