Sorting twenty-four bits
Three rows of eight invite a simple order: one drive type per row. Cross-head bits in the front row, star drive in the middle, hex and slotted at the back, each row running from small to large, left to right. Laid out like that, the block replaces reading the tiny stamp on each shank with knowing where to reach. The middle row is the awkward one, since its bits have neighbours on both sides, so put the type you use least there. If you would rather have every bit reachable from a side, two rows of twelve hold the same number in a block 118.2 mm long and 24.2 mm deep.
What to measure
Measure a bit across two opposite flats: 6.35 mm is the standard size and most bits read a few hundredths less. Sets sometimes include one or two bits with a thicker body, a magnetic holder or a socket adapter; those do not fit a 6.6 mm pocket and need their own holder. Then measure the place for the block. It needs 79.8 by 34.9 mm of bench or drawer floor, and the height with 25 mm bits in place is 27 mm.
Clearance, walls and material
The pocket clearance is 0.25 mm. Walls between pockets and around the block are 3 mm, and the block is 15 mm high over a 2 mm floor, so the pockets are 13 mm deep. In a block this size the fit shows up differently from a small strip: with twenty-four bits in it, a block with loose pockets rattles when the drawer is opened, and one with tight pockets lifts off the bench when a bit is pulled. If the block lifts, raise the clearance by 0.05 mm, or stick it down. PLA is suitable and gives the cleanest pockets.
Printing
Print flat with the pockets upwards and no supports. The block is mostly perimeters, because 3 mm walls separate everything, and it holds more plastic than its size suggests: allow about an hour and a half at 0.2 mm layers. A wide flat base like this is where the corners may lift in a cool room. A clean bed and a slower first layer usually prevent it; if a corner lifts anyway the block rocks on the bench, so stop and reprint with a brim instead of living with it.
Outline drawing
Top view, to scale. Pocket centres are 9.6 mm apart along a row and about 10.6 mm apart between the rows.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | bit_holder |
| Bits per row | count | 8 |
| Rows | rows | 3 |
| 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 | 15 |
| Floor under the pockets | floor | 2 |
All lengths are in millimetres. Outer size from these values: about 79.8 x 34.86 x 15 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.