Online Configurable Round or Hex (Allen) Bit Holder With Labels

Acknowledgments

The idea is based on Parameterized Allen Key Holder by xopn who provided configurable Allen key holders and a SCAD script that makes them. I wanted this bit holder to have labels and be configurable online.

I am not a novice to online CAD – Onshape – and thought it was time for me to take a look at their FeatureScript, as this is how one can generate dynamic content (such as a bit holder with any number of round or hexagonal holes).

I thought that converting the SCAD script to Onshape's FeatureScript would be easy. It was not! FeatureScript cannot make a hull around a random number of vertices automatically, and one needs to calculate the hull points. This is where AI came in: Google's Gemini calculated a minimal convex hull using Andrew's monotone chain algorithm, xAI's Grok figured out how to smooth it with arcs.

I will not tick the "AI Generated Content" box, since this is not what I think this box is meant to signify. In any case, in comparison to AI, I was racking my own brain even harder :). My first experience with FeatureScript was difficult because of the complexity of its features and lack of good tutorials. Gemini/Grok to the rescue, again.

Making Your Own Bit Holder

Follow the link to Onshape at the end of this page. Now look at the top left of the screen, where it says “Configurations”. These are parameters that modify the holder. If the “Features” panel partly blocks them, position the mouse on top of the “Features” panel until the mouse pointer changes to the “slide” icon and drag the “Features” panel down a bit. Also, widen the Configurations panel so you can see everything better. You can also double-click on the "Top" face of the cube in the upper right to make the bit holder model to face you.

To export the model from Onshape, first set all configurations and make sure your holder looks good. Then, right-click the "Bit Holder” tab and select “Export…”. Choose “Format: STL”,  “STL Format: Binary”, “Units: Millimeter”, “Resolution: Fine”.

Imperial Sizes To mm Conversion Table

The Onshape bit holder configurator expects all sizes to be in millimeters. Here is a convenience table to convert Imperial sizes to millimeters. If you are making a holder for screwdriver bits, those are usually 1/4" (6.35 mm) hex.

Printing

It is hard to know for sure what the Wiggle needs to be. Therefore, I'd suggest printing a thin key holder first. You can do it in the slicer by sinking the holder into the print bed. Do print all the sizes that you will want to see how they fit.

For a better fit, you may need to measure the keys (from flat to flat) with a caliper. Making a key holder from the hard plastics is also challenging, as the fit becomes loose over time. I hate to recommend it, but for hard plastics, you probably will need to make the openings just a bit too tight, and "work them out" for a better fit. Or use TPU.

The labels you see in the pictures are printed in a different color than the holder. This can be done with a single color printer by forcing a pause at the right layer in the slicer. In PrusaSlicer, the pause will be inserted before the selected layer is printed. The exact pause command is specific to a given printer. For my FlashForge Dreamer, it is "M25". For Prusa printers it is "M601", from what I can tell. You then can swap the filaments and resume printing by pressing a button on the printer's control panel / display.

Uploaded Models

I am thinking to upload just a few models here. The point of the configurable bit holder is that you make the one you want, for the number of bits you have, with the wiggle room you find desirable. Below I will list all parameters that were used for the uploaded models. If they fit your needs in general, you can easily re-create them by changing only the parameter(s) you want to adjust. 

File: Bit_Holder_Hex_Driver_PH_SL_SQ.stl (intended for 1/4" screwdriver bits, Phillips, Slotted, Robertson)
Sizes: 6.35 6.35 6.35 6.35 6.35 6.35
Labels: PH1 PH2 3/16 1/4 SQ1 SQ2
Wiggle: 0.2
Height: 8
Min. Border: 6
Min. Gap: 3
Rotation: 30
Hex Holes: yes

File: Bit_Holder_Hex_1-16_to_5-32.stl (intended for smaller size Allen keys)
Sizes: 1.59 1.98 2.38 2.78 3.18 3.57 3.97
Labels: /16 5/64 3/32 7/64 1/8 9/64 5/32
Wiggle: 0.2
Height: 8
Min. Border: 6
Min. Gap: 7
Rotation: 30
Hex Holes: yes

File: Bit_Holder_Hex_3-16_to_3-8.stl (intended for mid size Allen keys)
Sizes: 4.76 5.56 6.35 7.94 9.53
Labels: 3/16 7/32 1/4 5/16 3/8
Wiggle: 0.2
Height: 8
Min. Border: 6
Min. Gap: 7
Rotation: 30
Hex Holes: yes

File: Bit_Holder_Round_1-16_to_1-4.stl (intended for smaller drill bits)
Sizes: 1.59 1.98 2.38 2.78 3.18 3.57 3.97 4.76 5.56 6.35
Labels: /16 5/64 3/32 7/64 1/8 9/64 5/32 3/16 7/32 1/4
Wiggle: 0.2
Height: 8
Min. Border: 6
Min. Gap: 7
Rotation: 30
Hex Holes: no

CAD Link

https://cad.onshape.com/documents/ada8d5ed26dd9223ae910d7e/w/9f1648e12858ef3edfc17191/e/c97b5e215d4bac3a18347209