Brad Point Bit Case (5, 6, 8 mm, for fischer DuoPower anchors)

A case for three brad point bits, with a sliding dovetail lid that clicks shut. It holds the 5, 6 and 8 mm bits, which are the sizes for fischer DuoPower wall anchors. Each pocket is only as long as its own bit, so the case stays small: 122 x 28 x 12 mm.

Which bits

Century Drill & Tool brad point bits with straight, full-size shanks:

• 5 mm: Century 37305, 86 mm long

• 6 mm: Century 37306, 93 mm long

• 8 mm: Century 37308, 117 mm long

Lengths are from the Century 2025 catalog (page 32). Other brad point bits of the same diameter and length should fit too. If yours differ, see Make it fit.

I printed this and all three bits fit well.

How it works

Each bit lies in its own U-shaped pocket, 0.5 mm wider than the bit and 1 mm longer, with its top just under the lid so nothing rattles. The lid slides in on a dovetail from the open end. Near the end of its travel it snaps over a small bump with a flex tongue, so it stays shut in a pocket or a bag.

Small slots in the floor under the shank ends let you push a bit up from below to lift it out. There's a thumb scoop on the lid for sliding it open.

The lid reads "DuoPower Size-Specific / Brad Point Bits" with 5, 6 and 8 labels over their pockets. The text is raised 0.4 mm, so you can print it in a second color (see Printing).

Printing

• PLA, 0.20 mm layers, 4 walls, 15-20% infill.

• No supports. Print the case open side up and the lid top face up, as modeled.

• Two-color text: add a color change at the first layer above 2.0 mm on the lid (the 2.2 mm layer at 0.20 mm layers). The text is the only thing above that height.

• Fits a 180 mm bed.

Make it fit

The OpenSCAD file is parametric (OpenSCAD 2021.01 or later). Change these at the top:

• bits: the diameter and overall length of each bit. Add or remove entries for more or fewer pockets.

• clr_d: how much wider and deeper each pocket is than its bit (0.5 mm). Raise it if your bits have wide spurs.

• lid_clr: lid-to-groove clearance (0.15 mm). If the lid is tight, raise it to 0.20. If it rattles, lower it to 0.10.

• dome_h: height of the snap bump (0.6 mm). If the snap is too stiff, lower it to 0.5 or lengthen tongue_len.

• title: the lid text.

How AI Helped

This is my design. I decided how the case works and looks. An AI assistant worked with me on the OpenSCAD code to my specifications, checked the model's fit and printability, and helped me with the renders and documentation.