Oscillating multi-tool

How it works

An oscillating drive swings the accessory through a few degrees of arc at 11,000 to 20,000 swings per minute in the Fein FMM 250 and up to 21,000 per minute in the Dremel Multi-Max 8300. Fein lists an oscillating angle of 1.6 degrees for the FMM 250. Dremel gives 1.5 degrees to each side, a total of 3.0 degrees.

Because the arc is so small, an accessory can work precisely in narrow spaces, according to Dremel’s manual. Sanding sheets, scrapers, saw blades and rasps all use the same motion, and the user changes the accessory and the oscillation rate for the task.

The earliest tool of this kind found in the records read was a plaster-cast cutter. Stryker’s 1945 application describes a disk with a saw-tooth edge driven through a stroke of about one-eighth inch by a crank pin in a slotted arm. The patent says such a cutter cuts casts and other hard substances but does not injure yielding surfaces such as skin that it touches by accident.

Anatomy

Accessory holder and clamp: The Fein FMM 250 clamps accessories with a clamping screw and the FMM 250 Q uses a quick-clamping lever; the Dremel 8300 uses an accessory holder and blade washer.
Switch and speed control: Fein’s thumbwheel preselects the oscillation rate from 1 (lowest) to 6 (highest); the Dremel 8300 has a variable-speed slide switch.
Depth stop: Fein’s depth stop adjusts the depth of cut.
Dust-extraction connection: Fein’s suction device connects to a vacuum cleaner for dust-free operation.
Accessories: Saw blades, sanding sheets on a hook-and-loop pad, scrapers, rasps and grout blades. Dremel’s manual lists accessories for flush cutting door jambs, sawing copper water pipe, removing grout, removing vinyl flooring and carpet, and scraping paint and thinset.
Ventilation openings: The motor’s cooling air enters through them; Dremel warns not to cover the air vents with the hand.

Variants

Corded multi-tool: Fein’s FMM 250 draws 250 W and delivers 130 W.
Cordless multi-tool: Dremel’s model 8300 is a 10.8 V lithium-ion tool weighing 0.85 kg without its battery pack. Fein’s history lists a battery-powered SuperCut among its products of 2010.
Heavy-duty multi-tool: Fein’s SuperCut line is a heavy-duty class that, according to Tools of the Trade, already occupied the high-demand niche when Starlock mounts were announced.
Automotive glass-cutting tool: Fein says its oscillating cutting tool, now the Super Cut Automotive, was developed from its chassis saw to remove window glass bonded in place with silicone.
Plaster-cast cutter: The medical ancestor; Stryker’s patent describes a toothed disk with a one-eighth-inch stroke. Fein’s plaster cast saw was the basis of its oscillating power tools.

Specifications

Oscillation rate · per min: Fein FMM 250: 11,000–20,000. Dremel 8300: 3,000–21,000.
Oscillation angle · degrees: Fein FMM 250: 1.6. Dremel 8300: 1.5 each side (3.0 total).
Power input, corded · W: Fein FMM 250: 250 W input, 130 W output. Only one corded model has been read.

Made to

EN 60745-1
IEC 62841-1

Safety and care

Safety

Wear safety goggles or a face shield, a dust mask and hearing protection as the application requires, and protective gloves when changing accessories, which become hot after prolonged use (Fein; Dremel).
Dust from sanding and scraping can be hazardous: lead-containing coatings, some woods and metal give off harmful dusts, and the tool must not be used on materials such as asbestos (Fein).
Use plunge cuts only in soft materials such as wood and gypsum board (Dremel).
Use undamaged saw blades only; deformed or blunt blades can break (Dremel).
Keep the hands away from the sawing range and do not reach under the workpiece (Dremel).
Use detectors to find hidden utility lines in the work area before cutting (Dremel).
Do not scrape wetted materials or moist surfaces, and do not treat the surface with solvent-containing fluids, because the scraping warms the material and can release toxic vapors (Dremel).
Use the tool for dry sanding only, since water entering the machine increases the risk of electric shock (Dremel).
Hand and arm vibration occurs. Fein recommends work breaks when vibration is strong, gripping the tool only as firmly as necessary, keeping the hands warm and wearing its vibration-absorbing gel gloves.

Care

Clean the cooling-air vents once a week, or more often with frequent use, with a non-metallic tool, and blow out the interior through the vents with dry compressed air (Fein).
Metallic dust that accumulates in the housing can cause an electrical hazard (Fein).
Use only accessories recommended by the manufacturer (Fein).

Tips

Set the oscillation rate for the task
Fein’s manual recommends a high rate for sanding, sawing, rasping, and polishing stone and metal, a low rate for polishing varnish and veneers, and a medium to high rate for scraping.1
Sand with the whole pad and light pressure
Fein says to work with the whole surface of the sanding plate, not just the tip, using continuous motion. Extra pressure does not increase material removal and only wears the sheet faster.1
Offset a round saw blade to even out the wear
Fein says round saw blades can be loosened and attached offset, so that wear is uniform around the edge.1
Set the depth stop
The Fein FMM 250 has a depth stop that Fein lists as being for depth-of-cut adjustment.1
Let the accessory do the work, in several passes
Dremel’s manual says to lower the accessory lightly to the work, use very little hand pressure, and make a series of passes, cutting a little material on each until the desired depth is reached. It also advises practicing on scrap first.1
Choose the blade for what the wood may hold
Dremel says to check wood, particle board and building materials for nails and screws before sawing with HCS (high-carbon steel) blades, and to remove them or use BIM (bi-metal) blades.1
Scrape flat, with a high rate and light pressure
For scraping, Dremel advises a high oscillation rate on a soft surface such as wood, held at a flat angle with light pressure; otherwise the scraper can cut into the surface.1
Check which blade mount the tool takes
Tools of the Trade reported in 2015 that Fein and Bosch’s Starlock mounts come in three classes. Starlock blades fit Starlock, Plus and Max tools, Plus blades fit Plus and Max tools only, and Max blades fit only Max tools. The article adds that the blades keep a flat shank with a multi-mount hole pattern, combining the 12 holes of the Bosch mount and the star-shaped hole of the Fein mount, but still do not fit DeWalt/Porter-Cable, Dremel or Fein SuperCut mounts.1

History

Earliest documented

1945 (application filed 2 April 1945; patent issued 16 September 1947)

Kalamazoo, Michigan

Homer H. Stryker of Kalamazoo applied for a patent on a plaster cast cutter in which a toothed disk is oscillated through a short stroke of about one-eighth inch by a crank pin roller engaging a slotted arm on the cutter shaft. The patent says the cutter cuts casts and other hard substances but yielding surfaces and fabrics are not cut or injured, and that it has wider uses, such as cutting bone, plastics, wood and even metal.1

The oscillating tool began with a medical problem: cutting a hard plaster cast off a patient. Stryker’s 1945 application states its main objects as a cutting implement highly efficient for cutting casts that is not likely to injure the patient or the user, and one with a wide range of uses. The cutter strokes through about one-eighth inch, and the patent says it cuts casts and other hard substances but not yielding surfaces, and does not cut fabrics unless they are supported by a fairly rigid backing. The patent already lists bone, plastics, wood and metal among other materials the implement can cut.

Fein’s own history describes the same job for its tool two decades later. It places a plaster cast saw patented as a circular saw with an angular oscillating blade in its 1967 entry and says the crescent pattern of the oscillation cut through the hard cast without damaging the patient’s skin. Fein then gave the saw a more powerful gearbox, producing a chassis saw, and developed that into the oscillating cutting tool that removed bonded window glass, which Fein says no electric tool could do before. Fein’s universal grinder of 1986, with its triangular pad and rotary-oscillating motion, is the form from which Fein says the MultiMaster developed.

The tool’s form follows from the small arc. A swing of 1.5 to 1.6 degrees, repeated 11,000 to 21,000 times a minute, is what Dremel says allows precise work in narrow spaces. Fein’s manual sets the rate by task. Dremel describes cuts, scraping and sanding that reach into corners and flush against walls, floors and door jambs, and plunge cuts in soft materials.

Blade changing and blade mounts changed in two steps. Fein’s 2007 MultiMaster introduced the QuickIN clamping system, which Fein says significantly reduces the time to change tools. In 2015 Tools of the Trade reported that blades of different makers did not fit one another’s mounts, naming DeWalt/Porter-Cable, Dremel and Fein SuperCut mounts as incompatible with the multi-mount pattern, and that Bosch and Fein’s Starlock system would add a three-dimensional mount, tool-free changes without touching a hot blade, and three classes of power.

Timeline

1945
Homer H. Stryker applies for the patent issued on 16 September 1947 as US 2,427,580, Plaster Cast Cutter, describing an oscillating toothed disk driven through a one-eighth-inch stroke.1
1967
Fein’s history places its plaster cast saw in the entry for 1967: a saw patented as a circular saw with an angular oscillating saw blade, used in orthopaedics to cut plaster casts without damaging the skin. Fein says it formed the basis of its oscillating power tools.1
1985
Fein’s history places the oscillating cutting tool for automotive work here: a development of the chassis saw, with specially shaped blades, for removing window glass bonded with silicone. It is now the FEIN Super Cut Automotive.1
1986
Fein’s history places the universal Fein grinder here: a grinding disc shaped as a spherical triangle moved in a rotary-oscillating motion. Fein says it evolved into the MultiMaster, which saws, sands, scrapes, separates, rasps, polishes and cuts.1
2007
In January Fein launches a new generation of the MultiMaster with the QuickIN tool-clamping system, which it says draws on more than 40 years of experience in oscillation technology.1
2010
Fein presents a battery-powered SuperCut among two lithium-ion products.1
2015
On 1 December Tools of the Trade reports that Bosch and Fein will introduce the Starlock tool-mounting system in 2016, replacing the flat mounting interfaces then in use with a three-dimensional mount shaped like a bottle cap, and with three classes of tool and blade.1
2016
Fein’s history lists its Starlock oscillators, with the new tool mounting.1

Where the sources disagree

Which design of oscillating cutter came first?

Fein’s plaster cast saw, patented as a circular saw with an angular oscillating blade, appears in Fein’s 1967 entry and formed the basis of Fein’s oscillating power tools. The company page does not claim to be the first oscillating cutter.1
C. & E. Fein GmbH
A plaster cast cutter with a toothed disk oscillating through a one-eighth-inch stroke was applied for in 1945 and patented in 1947.1
US Patent 2,427,580 (Stryker)

Gaps in the record (7)

The Fein patent number and text for the plaster cast saw were not located. Fein’s page does not state the year of the patent, and the 1967 date comes from where the company’s timeline places the saw.
No source has been found connecting Stryker’s cutter to Fein’s; the two are shown as separate records.
Popular reference summaries that call Fein 1967 the origin of the oscillating tool, and that give an expiry date for its multi-tool patent, were not verified in any source read.
The year Fein first sold an oscillating multi-tool to the public and the years Bosch, Dremel and others entered the market were not sourced; the Dremel manual is undated.
Fein’s timeline entries carry only the year of the section under which they appear; the 1985 and 1986 placements rest on that layout.
Specifications are drawn from two manuals; no typical values or independent test data have been located, so buying is null.
The standard slugs are guesses; Fein’s manual lists EN 60745, EN 55014 and EN 61000-3 in its declaration of conformity, but the standards were not read.