Milwaukee 2781-20 M18 FUEL Lithium-Ion 4-1/2 in. - 5 in. Slide Switch Grinder with Lock-On (Tool Only)

Milwaukee Model: miln2781-20
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Milwaukee 2781-20 M18 FUEL Lithium-Ion 4-1/2 in. - 5 in. Slide Switch Grinder with Lock-On (Tool Only) Milwaukee Model: miln2781-20
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Product Features & specs :

Milwaukee 2781-20 M18 FUEL Lithium-Ion 4-1/2 in. - 5 in. Slide Switch Grinder with Lock-On (Tool Only)

The M18 FUEL 4-1/2 in. / 5 in. Slide Switch Grinder supplies maximum sustained power to complete the toughest grinding, surface preparation and cutting applications. The POWERSTATE Brushless Motor provides up to 10X longer motor life and lower cost of ownership. The M18 REDLITHIUM XC4.0 Battery Pack (Sold Seperately) delivers up to 4X more run time and 20% more power. The grinder features REDLINK PLUS Intelligence, the most advanced system of cordless power tool electronics, for maximum performance.
  • POWER TO GRIND means the World's first cordless grinder with corded performance
  • Same metal housing and gearing system as legendary high performance corded grinders
  • Thin body design and anti-vibration handle provides optimized balance to rest easily in your hands
  • Tool-free accessory changes and guard adjustments mean less downtime during work
  • POWERSTATE Brushless Motor delivers maximum power and up to 10X longer motor life
  • REDLINK PLUS Intelligence provides optimized performance, electronic clutch, and overload protection using total system communication between tool, battery and charger
  • REDLITHIUM XC 4.0 Battery Pack (Sold Separately) provides superior pack construction, electronics, and performance to deliver 2X more run-time and more work over pack life
What’s Included:
  • M18 FUEL 4-1/2 in. - 5 in. Slide Switch Grinder with Lock-On (Tool Only) -2781-20
  • Wheel Guard
  • Flange Nuts
  • Spanner Wrench
  • Tool Only - Batteries and Charger Sold Separately
Power Source
UL Safety
Wheel Diameter
4-1/2 in / 5 in
No-Load Speed (RPM)
CSA Safety
Switch Settings
Wifi compatibility
Batteries Included
Battery Type
Case Included
Bluetooth Compatibility
Motor Type
Spindle Thread
5/8 in - 11 in
Variable Speed
Switch Type
Arbor Size
5/8 in - 11 in
Charger Included
ETL Safety
Battery System
15 in.
3.27 in.
8.58 in.
5.8 lbs.
Warranty Term
5 Year

Reviews :

4.8 / 5.0
148 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Would you recommend this product?
Yes (21)
Powerful (16)
Easy To Use (14)
Ergonomic Design (11)
Value (5)
Heavy (1)
Uncomfortable to Use (1)
Best Uses
Jobsite (8)
Frequent Use (6)
Large Projects (5)
Small Projects (5)
Amazing tool
The battery life is insane!!! I love it. Ill buy other tools from milwaukee
August 24, 2020
Originally posted at
Great grinder
This grinder is great for making on the go cuts and grinding all sorts of materials. It’s got a lot more power than you would expect.
August 16, 2020
Originally posted at
4 1/2"/5" grinder
I use this grinder when installing door hardware. Used for cutting steel and alum. parts. Works great. It spins slower then my electric units but seems to make the blades last longer anyway. well balanced using the 5 amp hour battery.
August 8, 2020
Originally posted at
Highly recommended
This grinder exceeds my expectations every time I use it. Plenty of power and the battery lasts all day. The guard is easily adjusted and the blade. changes with no hassle.
August 1, 2020
Originally posted at
Great Product
Very portable, Easy to use, and very durable. Love this product
August 1, 2020
Originally posted at
Never a hook up
Gezzz hook me up with something already I spent a lot on Milwaukee tools
July 28, 2020
Originally posted at
I would buy Multiple
The tool is lightweight easy to maneuver comfortable grip I like the strength of the spin
July 19, 2020
Originally posted at
This thing is AMAZING!!!
I work on a farm so I use this grinder for a lot of different jobs and it gets them done every time.
July 4, 2020
Originally posted at
Definitely a must have!
Great tool lots of torque. Comfortable in the hand when up in a bucket truck.
June 22, 2020
Originally posted at
I would rebuy this tool
We use this grinder often works great, needs good battery
June 21, 2020
Originally posted at

Q & A :

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Browse 3 questions Browse 3 questions and 6 answers
How long can be used before recharge in production no stop ?
Edwin on Apr 19, 2016
BEST ANSWER: That is a very difficult question to answer, runtime depends on many variables. Without knowing whats being done with the grinder, continous runtime could be anywhere from 30 minutes to a couple hours with the 4Ah battery. Keep in mind, charge time is relatively short, with a couple of batteries you can get alot accomplished with little
The description states "Tool-free accessory changes," but a reviewer said that he needed a tool to remove the flange nut. The downloadable manual also states that a spanner wrench is required to tighten and loosen the flange nut. Also, if accessories can be changed without a tool/wrench, why is one included? Can wheels/accessories be installed and removed without a tool or not?
A shopper on Nov 25, 2017
BEST ANSWER: In almost all cases, you can swap blades without a tool. If the blade is the face, on the back of the head is a lever which unclamps the spindle. It is not enough to flip this lever up; you must flip it all the way forward. When you do, the spindle/arbor tension is released and you can unscrew the spindle-cap/arbor-nut with your fingers. If you don't understand how this works, you will probably overtighten the cap/nut and then need a wrench to get it off again.

So, wheels/accessories CAN be installed without a tool, if you don't go out of your way to make it more difficult than necessary.
Can you interchange the types of Milwaukee batteries with chargers and tools?
Frank on Oct 19, 2015
BEST ANSWER: All Milwaukee 18 volt lithium ion tools and batteries are compatible,so yes everything is interchangeable.