Check the length before anything else
The rack length is the spacing times the number of gaps plus the two end margins: eleven gaps of 20 mm plus two margins of 12 mm is 244 mm. That fits straight on a 250 or 256 mm bed, and diagonally on a 220 mm bed, where the diagonal is about 310 mm. Twelve full-size screwdrivers are a different matter: their handles need about 28 mm each, which makes a rack of well over 330 mm. For a full-size set, print two racks for six drivers and mount them end to end.
What to measure
Lay the twelve drivers side by side and find the widest handle; precision drivers are usually 10 to 16 mm across, often with a wider spinning cap on the end. The spacing must be at least the widest handle plus 3 mm, so 20 mm suits handles up to about 17 mm. Then measure the thickest shaft and the narrowest part of any handle. The 6 mm hole used here passes shafts up to 5 mm and catches any handle wider than 7 mm. If one driver in the set has a handle as slim as its shaft, it will fall through: give that one a bit holder instead.
Thickness and material
Slim drivers weigh little, so the shelf is 4 mm thick and only 26 mm out from the 4 mm back wall, a total depth of 30 mm. A short shelf bends less, and with twelve tools in a row a shallow rack also keeps the handles close to the wall where they are not knocked. PETG resists slow sagging better than PLA, though at this load either works. Keep the hole spacing at least 1.6 mm greater than the hole diameter, which the generator enforces.
Printing
Print it standing on the back wall, shelf pointing up, so the layers pass through the corner between wall and shelf. The 6 mm holes are then horizontal and print without supports. A part 244 mm long lying on a face only 28 mm wide wants to lift at the ends: use a brim, a clean bed and, for PETG, no part cooling fan on the first layers. Layer height 0.2 mm, four perimeters, 30 percent infill.
Fixing it
The back wall is 28 mm high and carries two 4.5 mm mounting holes, one near each end, for 4 mm screws. On a rack this long, a strip of double-sided tape along the middle of the wall stops it bowing away from the surface between the two screws.
Outline drawing
Top view to scale; the side profile is drawn larger. The first and last hole centres are 12 mm from the ends.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | screwdriver_rack |
| Number of holes | count | 12 |
| Hole diameter | hole_diameter | 6 |
| Hole spacing, centre to centre | spacing | 20 |
| End margin, hole centre to end | end_margin | 12 |
| Rack depth, front to back | depth | 30 |
| Shelf thickness | thickness | 4 |
| Back wall height | back_height | 28 |
| Back wall thickness | back_thickness | 4 |
| Mounting screw hole diameter | screw_diameter | 4.5 |
| Mounting screw holes | screws | 2 |
All lengths are in millimetres. Outer size from these values: 244 x 30 x 28 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 screwdriver rack 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.