The smallest practical 3D print for an electronics engineer - bit adapter

p.kaczmarek2 08 Feb 2022 02:25 5 3390 Cool? (+7)

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Hello my dears.
Here I will present what I think is the smallest practical 3D print for an electronics engineer that I have found myself using in a big way, a bit adapter for a small cordless screwdriver. It all started when I got a faulty screwdriver to repair, obviously without any bits and with a dead battery. I replaced the cell inside with an 18650, along with a module for charging directly from a micro USB (very convenient!), but I had a bigger problem with the bits - none of mine fit this screwdriver (not only did they not stick, they fell in too deep, with barely a tip sticking out). To that end, I designed a tiny adapter, which I'll present here.

Adapter design
Bit without adapter in screwdriver:

The thickness of the bit socket is 5/16" (approximately 0.79375cm).
I made the model in Blender:

I selected the thickness on the screwdriver side so that it would go in tight and hold solidly, as I will not be changing it. On the bit side I relied heavily on the magnet.

The weight of the print is a mere 1g:

I used PLA filament. I printed on my Ender 3 PRO.
I didn't get the dimensions right the first time and had to print twice, but with the price of the filament and the size of this object it's pennies.
Now it's time for the magnet - without it it wouldn't make sense. as the bits would fall out of the adapter:

Attaching the magnet with a dropout:

Finished:

The adapter does its job perfectly, the magnet holds the bits, you can unscrew and screw in. The more protruding bit makes it easier to access the screw head.

Summary
These types of simple prints really show the beauty and usefulness of having a 3D printer (combined with knowing the basics of object modelling). What impressed me about this print is that the cost really is extremely small (it's just 1 gram of filament, at £50 per kg that's pennies) and the usefulness is very high. Literally after half an hour I could already be screwing!
A screwdriver like this would normally go in the rubbish, but by converting it to 18650 with USB charging and printing this adapter, its life will be greatly extended.
I am continually impressed by how useful and widely available 3D printing is in our time and just wonder what will be around in 10, 20 years?
Meanwhile, a question for you - what have you managed to print that is practical and at the same time extremely cheap/lightweight, such that it was very useful and at the same time cost pennies?
PS: Of course I also have a full-fledged Makita clone with much more power, but such a small DIY toy charged from USB is sometimes more handy and e.g. faster for me to reach for it to e.g. remove a few screws from a PC case.
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p.kaczmarek2 wrote 13929 posts with rating 11734 , helped 630 times. Been with us since 2014 year.

Comments

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CosteC 08 Feb 2022 08:56

How much torque can such an adapter withstand? Is the screwdriver simply too weak to break the printed plastic? [Read more]

max-bit 08 Feb 2022 09:05

If you retract one into the other (no torsional moment) just squeeze inside the ABS it will hold a bit, but the bits are small so more securely these small bits ... than this plastic :) [Read more]

p.kaczmarek2 08 Feb 2022 12:48

This mini screwdriver is too weak to damage anything. On the other hand, I could (and maybe I will) print a second one out of curiosity and test it sequentially on different clutch settings of a full-fledged... [Read more]

noel200 15 Feb 2022 12:36

I also have this screwdriver. In my opinion it has a lot of torque. It screws long screws into wood. I bought mine when I didn't have a printer and I put a couple of small round magnets lubricated with... [Read more]

Janek_D69 18 Feb 2022 19:13

Adapters are available in almost every cheap kit, the problem with them is that they are of poor quality and the spring often falls out, so I used such a "patent" with a glued-in magnet in 3d printing... [Read more]

FAQ

TL;DR: A 1 g 3D‑printed bit adapter for a mini cordless screwdriver adds reach and magnetically holds bits—“The adapter does its job perfectly.” [Elektroda, p.kaczmarek2, post #19871183] Why it matters: It’s a near‑zero‑cost, quick print that revives otherwise unusable compact drivers for everyday electronics work.

Quick Facts

- Weight: approx. 1 g; at £50/kg filament, each adapter costs ~£0.05. [Elektroda, p.kaczmarek2, post #19871183]
- Measured driver socket thickness: 5/16 inch (≈0.79375 cm). [Elektroda, p.kaczmarek2, post #19871183]
- Magnet is essential; without it, bits fall out of the adapter. [Elektroda, p.kaczmarek2, post #19871183]
- Proven materials/tools: PLA on an Ender 3 Pro; modeled in Blender. [Elektroda, p.kaczmarek2, post #19871183]
- Extended reach: the more protruding bit eases access to recessed screws. [Elektroda, p.kaczmarek2, post #19871183]

What is this 3D‑printed bit adapter and who is it for?

It’s a tiny PLA sleeve that fits a compact cordless screwdriver and holds standard bits with a magnet. It targets electronics tinkerers needing slim, quick‑reach driving. The print weighs about 1 g and was designed specifically for a shallow, loose factory socket. [Elektroda, p.kaczmarek2, post #19871183]

How cheap and fast is it to make?

Material use is about 1 g. With filament at roughly £50 per kilogram, the part costs ~£0.05. The designer modeled it in Blender and printed on an Ender 3 Pro, completing the job in a single short session after one sizing retry. “Literally after half an hour I could already be screwing!” [Elektroda, p.kaczmarek2, post #19871183]

What dimensions should I start from?

Measure your driver’s bit socket. In the build shown, the socket thickness measured 5/16 inch (≈0.79375 cm). The adapter’s driver‑side walls were sized to press‑fit tightly and remain semi‑permanent, while the bit side depended on magnetic retention. [Elektroda, p.kaczmarek2, post #19871183]

Will bits stay in place without a magnet?

No. Without magnetic force the bits drop out of the adapter. The maker added a small magnet inside the bit end using a simple dropout to seat it. This provides reliable retention during light fastening tasks. It also keeps the bit from sinking too deep in the original socket. [Elektroda, p.kaczmarek2, post #19871183]

How much torque can a printed adapter handle?

On a small USB‑charged driver, torque is too low to damage the print. On a more powerful drill/driver, the adapter may fail unless walls are thickened. The author suggested testing on a full‑size driver would likely break it quickly, so reinforce if you must push torque. [Elektroda, p.kaczmarek2, post #19871860]

Does ABS grip bits better than PLA here?

One participant noted ABS can hold a bit when pressed in, but reminded that small steel bits are still stronger than the plastic. Quote: “...the bits are small so more securely these small bits ... than this plastic.” For this project, PLA succeeded in real use. [Elektroda, max-bit, post #19871417]

Which tools and settings did the original build use?

The adapter was modeled in Blender and printed in PLA on an Ender 3 Pro. The driver‑side fit was tuned to be tight and permanent, relying on geometry rather than a magnet. The bit‑side relied on an internal magnet to hold standard bits securely during work. [Elektroda, p.kaczmarek2, post #19871183]

Quick how‑to: How do I make and assemble the adapter?

Model a press‑fit driver‑side sleeve and a magnet pocket in Blender.
Print in PLA (≈1 g) and test fit; re‑scale if too loose.
Drop in and seat a small magnet on the bit side using a simple dropout. [Elektroda, p.kaczmarek2, post #19871183]

Can I revive a weak screwdriver with a new battery?

Yes. The author replaced the dead pack with a single 18650 cell and added a micro‑USB charging module. That upgrade extended the tool’s life and made charging convenient. Pairing the battery fix with the adapter transformed a junk‑drawer driver into a daily helper. [Elektroda, p.kaczmarek2, post #19871183]

What about a 26650 cell upgrade instead of 18650?

Another user installed a 26650 Li‑ion cell, kept the tool’s original contacts, and charged it externally. They also shortened the housing and reinforced it with hot glue. This shows multiple pack formats can work if you handle fitment and charging safely. [Elektroda, noel200, post #19885553]

Does this adapter improve reach in tight spaces?

Yes. By positioning the bit to protrude further, the adapter helps reach recessed or partially obstructed screws. This improves practical access in PC cases and small enclosures where short factory bits sit too deep in the chuck to engage reliably. [Elektroda, p.kaczmarek2, post #19871183]

Should I buy a ready‑made adapter or print one?

Cheap kit adapters often have poor retention; springs may fall out. A simple printed body with a glued‑in magnet restores secure holding. Printing also lets you customize wall thickness and bit projection, avoiding common failures in low‑cost metal adapters. [Elektroda, Janek_D69, post #19892217]

Any proof it can handle real work?

One participant reported the same compact driver “has a lot of torque” and can drive long wood screws. Combined with a magnetized socket, it becomes a capable light‑duty tool. Keep expectations aligned with size, and monitor heat and wear on plastic parts. [Elektroda, noel200, post #19885553]

What’s the main failure mode to watch for?

Without the magnet, bits slip out immediately. Under higher clutch settings on powerful drivers, thin walls can crack. If you must use more torque, increase wall thickness or switch to a metal adapter. Always keep magnetic retention clean of debris. [Elektroda, p.kaczmarek2, post #19871183]

What other small, high‑value prints are worth making?

Cable holders, hangers, and organizers deliver daily value for pennies. One user shared several handy Thingiverse organizers they rely on, demonstrating that tiny prints can transform bench workflow and storage without significant material cost. [Elektroda, noel200, post #19885553]

Any final verdict from the maker?

The creator’s assessment: “The adapter does its job perfectly.” They highlighted ultra‑low cost, quick modeling, and immediate usefulness. This project showcases how simple prints can extend tool life and boost productivity for electronics engineers and hobbyists. [Elektroda, p.kaczmarek2, post #19871183]