Tech & Gadgets · Head-to-head
CDI Torque Products 401SM Micro-Adjustable Torque Screwdriver vs Wiha 28418 SoftFinish TorqueVario-S 0.8 to 5.0 Nm
Which should you buy? Our verdict on both, pulled from our full The Best Torque Screwdrivers: 4 Compared (and One to Skip) comparison.
The 401SM is the one that behaves like an instrument: a cam-over clutch that releases rather than a click that asks you to stop, accuracy quoted as a percentage of the indicated value, and a serialized certificate traceable to NIST. The Wiha covers a wider and more metric-friendly band with the same plus or minus 6 percent and its own serialized certificate, and it is the better fit if your specs come in newton-metres.
CDI Torque Products 401SM Micro-Adjustable Torque Screwdriver
Buy itA cam-over clutch that disengages at the set torque, with accuracy stated as a percentage of the indicated value and a serialized certificate in the box.
- Cam-over torque limiting clutch: once it releases, continuing to turn does not pass more torque to the screw.
- Accuracy stated as plus or minus 6 percent of the indicated value, clockwise, which scales with your setting instead of being a fixed number.
- Individually serialized and supplied with a matching certificate of calibration traceable to NIST.
- Universal 1/4 inch hex bit holder with a rare earth magnet, so it takes ordinary insert bits rather than a proprietary blade.
- The accuracy claim is scoped to 20 to 100 percent of full scale, so nothing below 8 in-lb on this model is covered by it.
- Inch-pound scale only on the SM version; if your specs are metric you want the cN.m variant instead.
- CDI's own literature cites ASME B107.14M and ISO 6789, and ASME has since folded B107.14 into B107.300, so the cited edition is behind.
Wiha 28418 SoftFinish TorqueVario-S 0.8 to 5.0 Nm
Buy itA serialized, certificated adjustable driver covering 0.8 to 5.0 Nm with a 1/4 inch bit adapter, for people whose torque specs arrive in newton-metres.
- Plus or minus 6 percent accuracy tolerance, with a certificate of calibration and a laser calibrated scale marked and serialized for traceability.
- Wiha states the tool meets ASME B107.14m, EN ISO 6789 and BS EN 26789, which is more standards detail than most makers publish.
- Accuracy guaranteed to 5,000 cycles, which matches the default recalibration interval in ISO 6789-2:2017.
- 0.8 to 5.0 Nm is roughly 7 to 44 in-lb, a band that covers bicycle stems, optics rings and most small electrical terminals.
- It is a click type: it makes an audible and perceptible click and resets, but nothing stops you applying more torque after the click.
- The setting is changed with a separate Torque-Setter tool rather than a knob, which suits a bench and not a jacket pocket.
- The scale is newton-metres only, so an inch-pound spec has to be converted before you set it.
Side by side
| CDI Torque Products 401SM Micro-Adjustable Torque Screwdriver | Wiha 28418 SoftFinish TorqueVario-S 0.8 to 5.0 Nm | |
|---|---|---|
| Our verdict | Buy | Buy |
| Best for | Anyone who wants a torque screwdriver that is a measuring instrument first, with a document tying its accuracy to a serial number. | Electronics, electrical and bicycle work where specs are quoted in newton-metres and you want a certificate with a serial number on it. |
| Price tier | $$$ · premium | $$ · mid-range |
The bottom line
Our overall pick is the CDI Torque Products 401SM Micro-Adjustable Torque Screwdriver - A cam-over clutch that disengages at the set torque, with accuracy stated as a percentage of the indicated value and a serialized certificate in the box. Choose the Wiha 28418 SoftFinish TorqueVario-S 0.8 to 5.0 Nm instead if electronics, electrical and bicycle work where specs are quoted in newton-metres and you want a certificate with a serial number on it.
Want the full picture, including the other options we compared and the popular one we'd skip? Read the complete The Best Torque Screwdrivers: 4 Compared (and One to Skip).