Screwdriver Bits Guide — a practical guide for Australian trades from the team at Power Tools Direct Australia.
Torsion zones, S2 steel, PH vs PZ, and the five technique fixes that stop you rounding out bits and screws.
Screwdriver Bits Guide: In this guide
- It is almost never the screw’s fault
- Impact-rated vs standard
- Steel grades
- Match the profile exactly
- Technique that saves bits
It is almost never the screw’s fault
Bits round out for three reasons: the wrong bit profile, the wrong bit hardness, or bad technique. All three are fixable and none of them require a better drill. Browse screwdriver bits.
Impact-rated vs standard
A standard bit is hardened all the way through. It is stiff and precise, and under the shock loading of an impact driver it snaps.
An impact-rated torsion bit has a deliberately softer, narrower torsion zone behind the tip. That section twists slightly under each impact, absorbing the shock instead of transmitting it to the tip.
- Standard bits — hand drivers and drill drivers. Cheaper, more rigid.
- Impact / torsion bits — mandatory for impact drivers. Longer life under shock loading.
- Diamond or grit-coated tips — extra grip in the screw recess, resists cam-out but wears the screw head faster.
Steel grades
| Grade | Character | Use |
|---|---|---|
| CRV (chrome vanadium) | Softer, cheap | Occasional hand use |
| S2 tool steel | Hard, precise, brittle | Drill drivers, precision work |
| S2 with torsion zone | Hard tip, flexible shank | Impact drivers — the right default |
| Carbide / Tin coated | Very hard, wear resistant | High-volume production driving |
A pack of good torsion bits costs less than a single wasted hour undoing a rounded screw. Stop buying the cheapest bulk sets.
Match the profile exactly
Australian construction uses a mixture of Phillips, Pozidriv, square drive and Torx, and Phillips and Pozidriv look almost identical.
- Phillips (PH) — designed to cam out at high torque. Common on imported hardware.
- Pozidriv (PZ) — extra small ribs between the main flutes. Does not cam out. Using a PH bit in a PZ screw destroys both.
- Square drive (SQ / Robertson) — excellent grip, common in decking and cabinetry.
- Torx (T) — best torque transfer of the common profiles, and increasingly standard on structural fixings.
- Hex — coach screws and furniture fittings.
Technique that saves bits
- Push hard, in line with the screw. Most cam-out is caused by insufficient axial pressure.
- Keep the driver square. Even a few degrees off-axis concentrates load on one flute.
- Start slow. Seat the bit fully before applying speed.
- Use the right length. A 25 mm bit is more rigid and precise than a 150 mm one; use long bits only when access demands it.
- Replace worn bits. A worn bit destroys screws, and screws are more expensive to remove than bits are to replace.
Holders and magnets
A quality magnetic bit holder makes one-handed work possible and reduces wobble if it has a locking collar rather than just a magnet. Cheap holders introduce runout, which puts the bit slightly off-axis on every screw — the exact thing that rounds bits out.
Restocking bits?
Wera, Milwaukee, Makita and Vessel impact bits and holders.
The bottom line
Torsion zones, S2 steel, PH vs PZ, and the five technique fixes that stop you rounding out bits and screws. Everything we sell is genuine Australian stock with full manufacturer warranty, dispatched same day on orders placed before 1pm AEST from our Sydney warehouse. Standard delivery is $15.99, express is $32.55, and delivery is free on orders over $1,000.
Not sure which option suits your work? Talk to our team — we are tradies too. You can also browse the full power tool range, read the FAQs, or set up a trade account for ongoing pricing.
Frequently asked questions
Can I use a normal bit in an impact driver?
You can, briefly. It will snap or round out far sooner than a torsion bit — the false economy is obvious after one job.
What is the difference between PH2 and PZ2?
Pozidriv has additional small ribs at 45 degrees to the main slots. A PH bit in a PZ screw contacts on too little surface and rounds out.
Are expensive bits actually better?
Yes, measurably. Better steel, tighter tip tolerances and proper torsion zones translate directly into longer life.
Keep reading
- Best Impact Drivers in Australia
- Screwdrivers: Why Wera and Vessel Cost More
- Drill Bit Types Explained
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