What to measure
A hex bit is sized across flats: the distance between two opposite flat sides of the shank, not corner to corner. Close a caliper on two opposite flats of one of your bits. A standard quarter inch bit reads 6.35 mm, or a few hundredths under. Corner to corner the same shank is about 7.3 mm, and typing that number by mistake gives pockets the bits fall around in. If your set mixes brands, measure three or four bits and use the largest reading.
Clearance, walls and material
The pocket is the bit size plus the clearance: 6.35 plus 0.25 gives 6.6 mm across flats. In PLA that lets a bit drop in under its own weight and lift out with two fingers. PETG tends to print pockets slightly tighter and stringier, so use 0.3 mm for PETG. If you want the bits to stay put when the strip is turned upside down, try 0.1 mm and expect to push them in. The wall between pockets and the wall around them are both 3 mm, which leaves room for a fingertip between neighbouring bits.
Pocket depth
The strip is 12 mm high with a 2 mm floor, so each pocket is 10 mm deep. A common 25 mm insert bit then stands 15 mm proud, enough to read the size marking and to grip. For 50 mm power bits raise the strip height to about 20 mm, or they lean and knock each other over.
Printing
Print the strip flat with the pocket openings facing up, exactly as generated. No supports are needed, because every pocket is a straight vertical hole with a closed floor. Use a 0.2 mm layer height. The first layer matters less than usual, since the pockets do not reach the bed, but an over-squished first layer still widens the base and should be trimmed if the strip has to sit in a drawer bin. Three perimeters and 15 percent infill are plenty; the part is 99 by 13.6 by 12 mm and prints in well under an hour on most printers.
Outline drawing
Schematic, not to scale. Pocket centres are 9.6 mm apart.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | bit_holder |
| Bits per row | count | 10 |
| Rows | rows | 1 |
| Bit size across flats | across_flats | 6.35 |
| Pocket clearance | clearance | 0.25 |
| Wall between pockets | gap | 3 |
| Wall around the pockets | margin | 3 |
| Strip height | height | 12 |
| Floor under the pockets | floor | 2 |
All lengths are in millimetres. Outer size from these values: about 99 x 13.6 x 12 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 hex bit holder strip 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.