Torx T20 Screwdriver

A Torx T20 screwdriver with a blue and white handle, Blue Alpine part A00110-00, for $3.91. Several fasteners in our catalogue have a T20 drive, from small M4 flat heads to M5 x 20 mm bolts. This T20 screwdriver is the hand tool for all of them.

Screws in our range that take a T20 screwdriver

These are the T20 parts we list, all in packs of ten:

• M4 x 6 mm flat head T20, stainless (F00113-00)
• M4 x 10 mm pan head T20 Torx, steel (F00128-00)
• M4 x 12 mm flat head T20 Torx, stainless (F00104-00)
• M5 x 12 mm flat head T20 Torx, stainless (F00106-00)
• M5 x 20 mm flat head T20 Torx, stainless (F00121-00)

Not everything is T20, though. The M3 x 5 mm flat heads use T15, the M5 x 8 mm countersunk bolts use T25, and the 1/4-20 pan heads use T30. This driver won’t fit those properly.

Ordering replacements for one of those T20 screws? Check the length the right way. A flat head is measured from the top of the head to the tip, because the head sits down inside the countersink. A pan head is measured from under the head to the tip. Mix those up and you’ll get a screw that’s a few millimeters off. When you drive a flat head with the T20 screwdriver, stop once it sits flush; going further just pulls the cone into the material.

Telling a T20 recess from its neighbors

Torx sizes step up in small increments, and at arm’s length a T15, T20 and T25 recess all look like the same six-pointed star. Fit is the only real test.

Push the T20 screwdriver into the screw head and twist it gently, without turning the screw. In a true T20 it drops to full depth and has almost no free play. If it spins loosely before catching, the recess is bigger (probably T25). If it won’t go all the way in, it’s smaller, likely T15.

Don’t force a near fit. A worn or wrong-size bit cams out and rounds off the lobes, and once that’s happened nothing grips it cleanly again.

One more case: some Torx screws have a small pin standing up in the middle of the star. Those are tamper-resistant, and a standard T20 screwdriver won’t enter them at all.

Why Torx and not Phillips

A Phillips recess has sloped sides. Turn harder and the driver tends to climb up and out of it, which is cam-out. Torx uses six rounded lobes with nearly vertical walls, so the driver pushes against the sides of the lobes instead of a ramp. You need less downward pressure, and the tip is far less likely to slip and scar the head.

That’s a big part of why Torx shows up on so much equipment. The Torx article covers the full size range and the security versions.

Habits that keep a T20 screwdriver and the screws in good shape

• Clear any grime or old threadlocker out of the recess first.
• Line the shaft up with the screw before you turn.
• Start screws by hand for a couple of turns so they don’t cross-thread.
• Stop at snug on M4. Small screws don’t need much torque.
• Retire the driver once the lobe tips look rounded.

T20 screwdriver FAQ

Is this the same as a T20 bit?

Same tip size, different tool. A bit goes in a drill or a bit holder. This one has its own fixed handle, which gives you better feel on small fasteners and makes over-tightening less likely than with a drill.

Will it work on the T25 and T30 screws?

No. It’s too small for both and will round them out. Each needs its own matching driver.

You’ll find hex keys and the rest of the hardware under fasteners and tools, including the 5mm hex key with a loop T-handle. Stuck working out which screw you’ve got? Email or ring us at +1 (443) 514-5708; both are on the contact page.