Adjustable Torque Screwdriver

A torque screwdriver for small torques.

Compatible with 1/4 inch hex bits. You can also glue a small magnet inside of the hex indent to hold the inserts.

The torque limit is adjusted by adding/removing TPU inserts onto the arbor. Once the limit is reached the fins will deform and the screwdriver will slip with a slight click.

I have successfully tested the tool at around 1Nm; if you want to 3D print a torque driver/wrench for higher values I would recommend looking at some bulkier wrenches solutions (e.g. check out this brilliant model by A_R_B, handling 1-3Nm).

The TPU inserts come in 2 kinds: two-sided and one–sided:

• Two-sided are symmetrical (same torque clockwise or counterclockwise). 

• One-sided are asymmetrical, allowing a higher torque value in one direction. This is useful for cases when you need to unscrew something tightened to a slightly higher value. Example: 0.1Nm TPU insert is supposed to snap at 0.1Nm torque in one direction and at some unspecified higher value in the other direction.

You can print a stand that allows you to keep 2 screwdrivers.

❗Disclaimers❗

• This 3d printed solution doesn't provide precise torque values, but in many cases it can serve as a cheap custom solution for consistent torque

• The vertically-positioned arbor is long to print, but provides a smooth rotation in use. I know that the layers direction is not perfect for the load, but for the torques it's designed to operate at it shouldn't be an issue

Calibration

You can change the height of the printed TPU inserts to get custom values or to adjust the print for your materials.

I printed the inserts from 95A TPU, and measured the torque; I got the following values:

• 2.4mm height: 0.05 Nm

• 4.8mm height: 0.1Nm

You can also stack the inserts on top of each other to get a roughly combined value.

Print notes

• No supports needed

• Maybe a brim should be added for the inner arbor

Updates log

• 2026-04-06: Initial version released

Support the author

The model is free to use and published under CC-BY licence, however if you want to support the model author you can do it here: BuyMeACoffee