Contractor Converts Milwaukee Hackzall Into Tool That Untwists Cat6 in Two Seconds

A job demanding 50,000 custom Cat6 cables and 100,000 terminations pushed one contractor to rebuild a Milwaukee Hackzall into a portable Ethernet untwister that straightens twisted pairs in under two seconds. The tool, built largely from 3D-printed and laser-cut parts plus a toggle clamp, replaces machinery that normally needs a bench, mains power, and compressed air.

The contractor, who publishes as Analytical Horsepower on YouTube, first solved the problem conventionally. He bought a "Wire Straightening Machine" from Alibaba for $500. It worked, after a fashion.

Why the $500 machine was not enough?

The industrial unit clamps wire between two rubber grips under air pressure, then converts the motor's rotary motion into linear motion so the grip can untwist the cable. The catch is infrastructure: it wants a table, an AC outlet for its power brick, and a supply of compressed air. None of that travels well.

To take it into the field, he disassembled the whole machine. A 20V DeWalt battery with an adapter replaced the DC power brick. A push-button switch added power control. A portable bike pump supplied compressed air on the go.

It worked, until it did not. The converted machine remained too bulky for the tight spots where Ethernet cables sometimes terminate, such as behind a heavy-duty outdoor Wi-Fi 7 access point. Portability, it turns out, is not the same as maneuverability.

How does a reciprocating saw become an untwister?

He studied the principle rather than the product. Two flat, grippy surfaces grab the twisted cable and move back and forth; the motion untwists the pairs while clamping force keeps contact as the cable flattens. The realization followed: he needed only a reciprocating tool that could accept a clamp.

A reciprocating saw came first, but he rejected it as equally bulky and "not overly precise." The Hackzall offered the right balance of portability and precision. One detail sealed the choice: Milwaukee publishes a detailed data sheet, instruction manual, and parts breakdown. That documentation let him 3D-print the plastic parts accurately and laser-cut and bend the metal ones. A toggle clamp replaced the pneumatic piston, which simplified the design and cut its size and weight.

Trial and error followed, mostly in the grippy material for the clamping surfaces. The result: softer copper-clad aluminum cables untwist reliably in one pass in under two seconds. Harder 100% pure copper conductors — solid copper, or pure bare copper in the trade — need a pair-by-pair approach and a little more time. That is still faster than fingers.

When does the tool pay for itself?

Not for the occasional job. If a technician untwists a few cables a month, the tool is not worth the shelf space. At the scale of a 50,000-cable project, the arithmetic changes. Half a minute saved per cable end compounds to more than 830 cumulative hours of labor across the jobsite.

The first-generation design leaves room for refinement. Commenters suggest extending the toggle clamp handle so it reaches the trigger and activates the tool in one motion. Integrating the mechanism into a crimper also looks plausible, which would fold two steps of termination into one tool. For now, the Hackzall conversion stands as proof that a documented parts list plus a boring workshop staple can outperform imported machinery at one-tenth the fuss.