{A cordless drill and screwdriver share many similarities, which is why I have lumped them together. As I started with screwdrivers this section will explain the technical lingo of the power tools, whilst the Drill subheading will just list recommended features and specs for specific uses.}

Screwdriver

DSC00008Without a doubt a cordless screwdriver would be a valuable addition to my toolbox, the question though is which one? Hoping to find a clear winner I read through countless of Top 10 lists, searching for the ‘number one screwdriver’. Regrettably, this only raised more uncertainty as it appears the tile is highly disputable. Hitachi’s Pencil Driver topped quite a few lists, but at only 3.6 volts, it seems to be aimed at light housework… though some reviewers insist otherwise.

Concluding I should be able to make a choice based on knowledge rather than popular opinion, I have broken down the key aspects that one should consider when purchasing a cordless screwdriver. My hope is that this will help me make an educated decision.

BATTERIES

Lithium-ion batteries are the preferred supply of power for cordless power tools for a number of reasons. Typically lighter than other rechargeable batteries, this becomes an obvious advantage when wielding a screwdriver with one hand. The batteries are also highly reactive meaning that they can store a lot of energy. This can equate to 150 watt-hours of electricity per kilogram of battery. In comparison a Nickle-Metal Hydride batteries store between 60 – 100 watt-hours and Lead only 25.

Lithium batteries also hold their charge better, losing only 5 per cent per month and without memory effect, meaning you don’t have to completely discharge before re-charging. (Memory Effect refers to the problem of batteries remembering shortened charging cycles.) They are designed for hundreds of charges.
That said, Lithium-ion batteries only last two to three years from the date of manufacturing and discharging completely can destroy the battery. (Tip: Check manufacturing dates of battery)

VOLTAGE

A higher voltage will mean more power, so whilst cordless screwdrivers can range from 2.4 to 12 volts, the 12v will drive a screw more easily and faster than a 2.4v. Anything less than 3.5v is not ideal.

  • 6-volt screwdrivers are designed for light duty tasks- hanging picture frames or assembling furniture.
  • 6 to 7.2 volts, medium duty
  • 8 up, heavy-duty tasks
RPM

RPM measures how many rotations per minute the driver makes. The higher the number, the faster the driving of the screw. An adjustable speed is always handy. 180 rpm is adequate for house work, medium work at least 600 rpm, heavy work will require speeds over 1500 rpm.

TORQUE

This is a measure of the force used to drive the screw and will determine if the screwdriver can drive into dense materials. Being able to adjust the torque means you can control how much force is applied and can prevent the screws from stripping or damage to the bit. Torque is measured in NMs (Newton Metres). Some drivers may have two gears, this can give you a higher RPM. This may be listed as Clutch Settings.

The below table is more applicable to drills but provides an example of the range of numbers to think about.

WEIGHT

The bigger the tool, the heavier it is likely to be, so this needs to be kept in mind when deciding. Though a driver may not feel heavy at first, it can begin to weigh on you when driving screws over and over. Transportation should also be considered.

DESIGN

Inline- straight like a traditional screw driver, easier to get in tight spaces.
Pistol-shaped like a gun, far more common due to comfort.
Ensure the switch between fastening and loosing is within easy reach.

Brushless Motor?
Brushless Motors allow the tool to adjust for the task, meaning it can draw more power when it feels resistance and vice versa. Because less friction is created, the motor releases less heat which will, in turn, make the tool last longer. The motor is smaller but can produce more power, so the tool is lighter, more efficient and drains batteries considerably slower.

Application
As I perused cordless screwdrivers I took down some numbers to gain a picture of the differences between models.

Bosch PSR Select HITACHI DB3DL2 deWALT DCF610D2-XE Milwaukee M12 Fuel 2402-22
BATTERY Lithium ion x1 Lithium ion x2 Lithium ion x2 Lithium ion x2
CHARGE TIME (mins) 240 30 30
VOLTAGE (v) 3.6 3.6 10.8 12
RPM 210 200/600 < 1050 Two speeds 0-450/1-1700
TORQUE (nm) 4.5/3.5 5 8 31
WEIGHT (kg) 0.5 0.6 0.96 1
DESIGN Pistol Variable Pistol Pistol
OTHER Bit cartridge Stands up by itself adjustable torque
LED one yes three one
WARRANTY 2+1 years 3 years 3 years 5 years
PRICE ($) 78 (Bunnings) 185 (Sydney Tools) 239 330 (Total Tools)
Drill

DSC00010BATTERY
There isn’t much of a difference between the tools in regards to battery- lithium is best and do ensure to get a kit with a spare.

VOLTAGE
As it’s the drill that one reaches for when a screwdriver can no longer drive through a material, it’s clear that more grunt is required. Voltages range from 12v to 20v.
12 volt now being for light work, 14.4 for medium, 18+ for heavy.
That said corded drills have a higher voltage still so these would be used for any truly heavy work.

The higher the voltage the heavier the tool will be- so again keep this is mind.

RPM and TORQUE
Cheap drills will only operate at one speed, but most will have two (ie; 300 and 800rpm.)
A drill with variable speed adds great versatility- a dial allows you to vary the speed from 0 to the top of each range. This means you can use your tool as both a drill (high speed) and screwdriver (low speed, high torque). If drilling is going to be the main activity a top speed of greater than 1000 is recommended.

A hammer action will allow you to drill into bricks and concrete. Adjustable torque means you can set the drill to stop turning once it meets a certain resistance

CLUTCH
A clutch can ensure you won’t overdrive a screw and protects the motor if there is too much resistance. A good drill will have at least 24 settings. The lower settings for small screws, the higher for larger.

DESIGN
Pistol and T Handle.
The latter tends to be more comfortable for drilling and allows you to stand the tool up. A pistol grip does allow greater force to be applied.

I haven’t yet a conclusion on either of these but hopefully when I head in-store to check them out in real life, I will at least feel comfortable to talk to a sales assistant!

{The photographed tools are courtesy of my Father’s shed- let’s just say I can’t wait to get my own cordless screwdriver… but the Bosch drill is very decent for around the house. }

 

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