OpenSCAD twist drill bit / reamer - Customizable

A fully customizable twist drill bit or reamer, with many options:

• Left or right handed
• Any helix angle from 0 to 85 degrees
• Section of either a twist drill bit or a reamer (straight sides)
• Cylindrical or conical flute
• Shank independent from the flute; you can set it at other diameter, number of sides, and add a groove to it (such as the quick-release shape of electric screwdrivers).
• Installer bit option
• Parametric point angle (from 0 to 60 degrees)
• Plus, a collection of example presets for the OpenSCAD file, and a PDF to help you use the OpenSCAD customizer as a power user! (To use the presets, just drop the .json file found under “Other Files” in the same folder as the .scad file.)

But is this any good??!?

Short answer: use abrasives.

Longer answer: It can be actually practical if you print it in a harder, more abrasive material than the one you're going to drill, it's intended to be used to polish or enlarge existing holes rather than making a new one, and works with low-speed (and usually high-torque) devices. So, use it with an electric screwdriver rather than a masonry-killer high-power percussion drill, and just don't expect to make a brand new hole.

You can also use a more regular plastic for printing, and use instead polishing compound or diamond paste.

Just remember, when doing your own bits, that lower helix angles are usually intended for lower speeds, and high helix angles for higher speeds; you will use normally just low speeds, but YMMV.

Printing tips

Unless you're making sturdy short and thick bits, it's very likely that if you print the bits unsupported, they will wobble and topple. It's just leverage.

So it's very recommended that you use organic supports. You don't need to overdo them (you rather need to not overdo them!), just to make sure that they “envelop” the bit by two or three sides. It's better to use paint-on supports from build plate only, painting some spots at the shank and tip here and there, until you have the bit surrounded, but not so much that it's going to be a pain to remove.

As you'll see, the supports won't actually make contact with the bit, just act as a shield to prevent toppling and too hot small layers.

Also, there will be usually no advantage in printing at anything below 100% infill (so use 100%), and beware of stringing. Even with huge angles, overhangs won't usually be a problem. A 0.2 layer height works fine, but avoid vase mode, except for gigantic bits. (You can make a drill-bit-shaped planter, y'know…)

And that's not all…

Although there are no samples included, the OpenSCAD file also allows to create installer bits. These are your regular twisted drill bit —longer, if anything— with a hole near the tip. These are used, for instance, to pass (insulated) cables and wiring through walls and plates. You make a pass-through hole with the bit (or another one), insert the bare wire in the hole (twisting it around the bit flute, if needed) and remove the bit, which will drag the wire (and cable) with it; voilà, the cable has passed! (Pretty much like a needle threader, in fact.)

Of course, these can also be used as drill bit protectors, to keep your good titanium-coated tools away from annoying neighbours and/or inlaws; print them in silver and gold using Z-based color change (or any other combination you want), tell your pests that they are “specially made in a polymeric filled alloy” (not untrue) and that “they require that their users know what they're doing”; absolutely insist in them wearing safety glasses. Well of course they will “know what they're doing” (ahem) and, once they've ruined your “specialty” drill bits and/or fused them with something, they will never ask you for your bits again! Ain't that wonderful?

Goes without saying that these can also work nicely as props for costumes; a TPU bit in a slow-speed machine may look menacing, but will be as wobbly as quirky. It's still spooky season, after all!