Parametric Bit Case for 1/4" and 4 mm Bits

This compact bit holder is convenient if you need to carry both sizes in a tool bag. The base and the lid are held together by cylindrical magnets and the lid can be used to collect screws while you work.

I included some variants as STL-files. They use 5 x 1 mm cylindrical magnets that must be glued in (superglue works fine). Each variant comes with either tight or loose tolerances. The tight variant is the one I used to print in TPU 95A, the loose variant is the one I used to print in PLA. If you can, use TPU, as it retains the bits better, but PLA or other common materials also work if your are careful with the tolerances.

For a custom case that really fits your needs and the tolerances of your printer, you will need to use the included FreeCAD-file and experiment a bit. It allows customization of most parameters through a spreadsheet. When you edit the parameters, the model will be recomputed automatically. Parameter names should be self-explanatory, examples are case_height, case_depth, num_small_slots, num_small_rows, magnet_dia etc. Make your adjustments and export it through the mesh workbench. I advise you to print a small test model first, to check if the tolerances are ok (I printed this about 5 times until it was good).

It is not easy to design the slots that hold the bits. Either they sit so tight, that you can't get them out without using pliers or they sit too loose and fall out easily. Also the dimensions can be a little bit different for each slot even within the same print. And lastly, not every bit is manufactured to the same tolerances. The approach I chose for this model uses a slightly tapered bit slot, which is wider at the top and narrower at the bottom. This makes insertion and extraction a little bit easier.  The taper is adjustable in the table through the parameters small_slot_width_top, small_slot_width_bottom, big_slot_width_top and big_slot_width_bottom.

Furthermore I stretched the bit slots in the y-dimension, which allows to wiggle the bits out easily (this is not configurable in the table at this time).

Print info TPU 95A

Filament: Ultimaker Black TPU 95A

Printer: Ultimaker S5

Layer Height: 0.2 mm

Perimeters: 3

Infill: Gyroid, 30 %

Supports: None

Adhesion: None

Print info PLA

Filament: Unbranded PLA (Generic PLA profile)

Printer: Prusa i3 MK2

Layer Height: 0.2 mm

Perimeters: 2

Infill: Gyroid, 25 %

Supports: None

Adhesion: None