Corded drill

How it works

A universal motor, powered through the cord, turns a gear train that drives a threaded spindle carrying the chuck. The Milwaukee parts list for a 1/2-inch drill names an armature, a field, carbon brushes, a gear case with an intermediate pinion and gear, a spindle and spindle gear, ball and needle bearings and a switch. The operator pulls the trigger to start and releases it to stop. In the Milwaukee manual the farther the trigger is pulled, the greater the speed, and a lock button holds the trigger on for continuous full-speed use.

A forward and reverse switch sets the direction of rotation. The manual says an interlock prevents reversing while the motor runs and still advises waiting for a full stop before reversing. A left-hand thread screw inside the chuck keeps the chuck from loosening when the tool is run in reverse. Because the tool draws its power from the line, its speed range and its torque are set by the motor and gearing, and the manual lists separate models for different no-load speeds.

The cord defines the rest of the tool. The manual requires either a grounded tool with a three-prong plug or a double-insulated tool, and it gives a table of minimum extension-cord wire gauge by cord length and the tool’s amperes. OSHA’s construction rule requires electric power tools to be of the approved double-insulated type or grounded.

Anatomy

Chuck: Holds the bit. The Milwaukee manual covers keyed chucks, tightened in three holes with a chuck key, and single- and double-sleeve keyless chucks, and it describes a spindle lock on the keyless models.
Side handle: A clamp-on auxiliary handle fitted over the chuck end of the gear case, with locking keys that seat in detents on the case to keep it from slipping.
Gear case: Houses the gear reduction between the motor and the spindle.
Motor housing: Contains the armature and field and the brushes; the service parts list also shows a motor housing and bearings at the commutator and pinion ends.
Trigger and lock button: Variable-speed trigger in the pistol grip. The lock button holds it on for continuous running.
Forward/reverse switch: A slide switch above the trigger that sets the direction of rotation.
Pistol grip: The handle below the motor with a trigger inside a guard, as claimed in the 1917 Black & Decker patent.
Cord set: Power cord with a three-prong plug on grounded models. The manual describes a quick-release cord connector on some models and a cord clamp on the handle of the older 1/2-inch drill in the parts list.

Variants

Pistol-grip drill: The common form, with a straight handle below the motor and a trigger switch, from the 1917 Black & Decker patent onward.
3/8-inch and 1/2-inch drills by speed range: In the Milwaukee manual the lighter models run at no-load speeds up to 2,500 or 4,000 rpm and the heavy-duty models run at 0 to 1,200 or 0 to 850 rpm with a side handle. The manual lists a higher bit capacity for the slower models.
Early industrial electric drill: The 1889 Melbourne electric rock drill of Brain and Arnot, a large machine built for mining and not portable, which the sources set apart from the hand drill.
Hand drill with an electric motor: Fein’s drill of 1895, which its company describes as a hand drill combined with a small electric motor, and the 1925 British Wolf drill (1/2-inch chuck, 100-watt universal motor at 500 rpm, 5 lb 8 oz) in the Science Museum Group collection.

Specifications

Supply · V AC: 120 (Milwaukee corded drill manual)Milwaukee manual, alternating current only.
Current · A: 7 for the 0100-20 to 0202-20 models; 8 for the 0299-20 to 0302-20 modelsMilwaukee manual; an example from one maker, not a survey.
No-load speed · rpm: 0 to 850 (heavy-duty) up to 0 to 4,000 (light-duty)Milwaukee manual lists 850, 1,200, 2,500 and 4,000 rpm models.
Maximum twist bit in wood or steel · in: 3/4 on the 850 rpm models; 1/4 on the 2,500 and 4,000 rpm light-duty modelsMilwaukee manual applications table.
Chuck capacity · in: Not extracted from the sources read; the parts list shows a 1/2-inch chuck on the 1/2-inch drill.

Made to

IEC 62841-1
IEC 62841-2-1
UL 62841-2-1

Safety and care

Safety

The Milwaukee manual instructs the user always to use the side handle on tools rated 1200 rpm or less, and to hold or brace securely because a binding bit produces a high rotational force that drives the tool against the direction of the bit.
The manual instructs the user to check the work area for hidden pipes and wires before drilling and to hold the tool by its insulated gripping surfaces, because a bit that contacts a live wire can make exposed metal parts of the tool live.
The manual instructs the user to unplug the tool before changing accessories or making adjustments and to remove the chuck key after each use.
The manual instructs the user to clamp the workpiece securely and to use backing material to prevent damage at breakthrough.
The manual states that dust from drilling can contain chemicals including lead from paint, crystalline silica from masonry and arsenic and chromium from treated lumber, and advises ventilation and an approved dust mask.
OSHA 29 CFR 1926.302 requires electric power tools to be of the approved double-insulated type or grounded.

Care

Before use, examine the general condition of the tool and inspect the switches, the tool cord set and any extension cord for damage. Check for loose screws, misalignment, binding of moving parts and broken parts, and tag a damaged tool “do not use” until it is repaired (Milwaukee manual).
Under normal conditions relubrication is not necessary until the motor brushes need replacement. After six months to one year, depending on use, the manual advises returning the tool to a service facility for lubrication, brush inspection and replacement, and mechanical inspection and cleaning of gears, spindles, bearings and housing.
The manual says never to disassemble the tool or attempt any rewiring of its electrical system and to send it to a service facility for all repairs.

Tips

Tighten a keyed chuck in all three holes
The manual says to place the chuck key in each of the three holes in the chuck in turn and turn it clockwise to tighten securely. A chuck tightened at one hole only is less evenly clamped on the bit shank.1
Center the bit and lift it off the bottom of the jaws
The manual says to center the bit in the jaws and lift it about 1/16 inch off the bottom before tightening by hand to align the bit. It also says dirt on the shank or jaws may prevent the bit from lining up properly, so both should be clean.1
Match the speed range to the bit size
The applications table pairs each model’s no-load speed with the largest bit it is rated for. The slow 850 rpm models are rated for twist bits to 3/4 inch in wood or steel and the 2,500 and 4,000 rpm models to 1/4 inch, so a large bit belongs on a slow, high-torque drill.1
Brace the body against the reaction
Figures in the manual show the tool braced against the floor, against the operator’s leg and against a stud so that the reaction from a binding bit is taken by a fixed object. The manual lists sharp bits, the correct bit for the material and care in pitchy, knotty, wet or warped wood as ways to reduce binding.1
Read the dust in masonry
For masonry the manual calls for high-speed carbide-tipped bits and says that a smooth, even flow of dust indicates the proper drilling rate. It says not to let the bit spin in the hole without cutting and not to use water to settle dust or cool the bit, because both actions damage the carbide.1
Do not click a stalled drill on and off
If the tool is about to stall the manual says to hold firmly and reduce pressure to let the bit regain speed. If it stalls, release the trigger at once, reverse the motor, remove the bit and start again, because pulling the trigger on and off against a stalled drill can damage it.1

History

Earliest documented

1889 (patent, 20 August 1889, as reported); portable hand-held drill 1895

Melbourne, Victoria (1889 patent); Stuttgart, Germany (1895 hand drill)

Two secondary accounts, Create Digital and EBSCO Research Starters, say that Arthur James Arnot and William Blanch Brain patented an electric drill in Melbourne in 1889; EBSCO adds that Frank Baker was a third patentee and that the patent called it “an improved electrical rock-drill, coal-digger or earth-cutter.” Create Digital describes it as a large drill for mining that could not be carried and says the first portable hand-held electric drill is credited to Fein of Stuttgart in 1895. FEIN’s own history states that in 1895 its employees combined a hand drill with a small electric motor, and calls it the world’s first power tool. The 1889 patent document itself has not been read.1 2 3

The corded drill began as an industrial machine. The two secondary accounts agree that the 1889 Melbourne patent of Arnot and Brain was for a drill to cut rock and coal, and Create Digital says it was heavy enough that it had to be set down to be used. Create Digital also names the cable as a hazard in a mine. The same article credits Fein of Stuttgart with the first portable, hand-held electric drill in 1895 but says that drill was larger and needed two hands. FEIN’s own history describes the 1895 drill as a hand drill with a small electric motor. These accounts differ on who was named on the 1889 patent and who built the 1895 drill, and the differences are set out under disputed.

The grip and the trigger came next. The 1914 Black & Decker application says that on practically all portable electric drills then in use the operator had to release some of the grip to work the switch, and it claims a pistol-grip support with a finger-operated trigger beside the motor. FEIN says its own pistol-shaped prototypes of 1918 followed an American model. The form of the corded drill that remains in use, a motor behind a chuck with a handle and trigger below it, is the form of this patent, although the patent calls the electric drill itself a tool of known construction.

The tool was then made for sale in different sizes. Milwaukee’s predecessor, according to Vintage Machinery, sold the Hole Shooter in 1/4-inch and 1/2-inch sizes after a design patent filed in 1921, and the 1925 British Wolf in the Science Museum Group collection had a 1/2-inch chuck with a 100-watt motor at 500 rpm. Black & Decker says it built its millionth 1/4-inch home utility drill in 1951. These dates show the corded drill moving from the shop to the home, but no sales or production series has been read, so the sources do not measure how fast.

Present corded drills are specified by speed and capacity, and the speed range sets the job. A current Milwaukee manual lists models from 850 rpm, rated for twist bits to 3/4 inch, to 4,000 rpm, rated for bits to 1/4 inch, and requires a side handle on any model rated 1,200 rpm or less because a binding bit applies a high rotational force to the body. A keyed chuck and a chuck key are standard on the heavy models, and the manual describes keyless chucks on others. The cord is the principal limit: the manual requires grounding or double insulation and gives minimum extension-cord gauges, and the cordless drill-driver covered in its own entry removes that limit.

Timeline

1889
Arthur James Arnot and William Blanch Brain patent an electric rock and coal drill in Melbourne on 20 August, according to EBSCO Research Starters and Create Digital. Create Digital describes it as a large mining drill that was not portable.1 2
1895
FEIN of Stuttgart combines a hand drill with a small electric motor. The company calls the result the world’s first power tool.1
1908
FEIN becomes what it calls a specialized factory for power tools and works first to give its drill more power and less weight.1
1910
S. Duncan Black and Alonzo G. Decker launch a machine shop in Baltimore, according to Black & Decker’s milestones page.1
1914
Black and Decker file an application on 4 December for an electrically driven tool with a pistol-grip support and a trigger.1
1917
US Patent 1,245,860 is issued to Black and Decker on 6 November. The specification says that on practically all earlier portable electric hand drills the operator had to relax the grip of at least one hand to reach the switch.1 2
1918
FEIN builds its first pistol-shaped prototypes, which the company says follow an American model.1
1921
Arno H. Petersen of Milwaukee files a design application on 24 June for an electric drill, and US Design Patent 59,678 is granted on 15 November.1
1922
According to Vintage Machinery, the A. H. Petersen Manufacturing Co. introduces its Hole Shooter drill in 1/4-inch and 1/2-inch sizes. The account says Henry Ford reportedly asked Petersen for a small drill for assembly lines.1
1925
S. Wolf & Co. of London make the British Wolf electric motor drill, a 1/2-inch chuck drill with a 100-watt universal motor at 500 rpm weighing 5 lb 8 oz, now in the Science Museum Group collection. In the same year, according to Vintage Machinery, Albert F. Siebert joins the Milwaukee drill company as sales manager.1 2
1951
Black & Decker says the one-millionth of its 1/4-inch home utility drills leaves the assembly line.1

Where the sources disagree

Who invented the first electric drill, and where?

Arthur James Arnot and William Blanch Brain patented the electric drill in Melbourne in 1889, a large machine for rock and coal.1
Create Digital (Australia)
Arnot patented it on 20 August 1889 together with Brain and a third man, Frank Baker.1
EBSCO Research Starters
In 1895 FEIN’s employees combined a hand drill with a small electric motor, which the company calls the world’s first power tool.1
FEIN (company history)
The first portable hand-held electric drill is credited to the brothers Wilhelm and Carl Fein in 1895, though it was large and needed two hands.1
Create Digital (Australia)

Which drill came first, the hand-held one or the pistol-grip one, and who made the pistol grip?

Black and Decker applied in 1914 for a pistol grip with a trigger switch, granted 1917.1
US Patent 1,245,860
FEIN’s first pistol-shaped prototypes were built in 1918 on an American model.1
FEIN (company history)

When did the Milwaukee Hole Shooter appear?

Design patent filed 24 June 1921 and granted 15 November 1921 to Arno H. Petersen for an electric drill.1
US Design Patent 59,678
The Hole Shooter was introduced in 1922 in 1/4-inch and 1/2-inch sizes.1
Vintage Machinery (secondary account)

Gaps in the record (8)

The 1889 Arnot and Brain patent has not been read, so the patentees, the date and the wording rest on two secondary accounts.
The Fein drill of 1895 is known only from FEIN’s own history and Create Digital, and neither names a patent or a model.
Black & Decker’s early drill sales and the Hole Shooter’s production have not been sourced.
The Henry Ford account of the Hole Shooter is a reported anecdote in Vintage Machinery and is not documented here.
How the corded drill displaced the brace and bit and the breast drill is not sourced in this entry.
No independent published test of corded drills has been sourced, so buying is null.
IEC 62841-2-1 and UL 62841-2-1 have not been read; the standard slugs are inferred.
The specs rest on one maker’s manual, not a survey; chuck capacity is missing.