Ridgid Octane 18V Brushless Grinder Review

PTR Review
  • Build Quality 9.0
  • Power 9.5
  • Ergonomics 9.5
  • Feature Set 8.0
  • Value 10.0

The Ridgid Octane 18V Brushless Grinder has the power to go toe-to-toe with anyone's cordless 4-1/2-inch grinder at a much lower price than premium models. The trade-off is that you'll miss out on a few features that premium models have. 

Overall Score 9.2 (out of 10)

In one of those perks-of-a-tool-review-publication scenarios, we’ve got the Ridgid Octane 18V Brushless Grinder in-house before its Q1 2019 availability. This impressive grinder launches alongside a 7-inch model, so we know Ridgid has the muscle to make this thing work.


  • Outstanding power for the 4-1/2″ class
  • Brushless motor
  • Slim handle profile
  • Excellent value
  • Visual overload indicator


  • Missing a few features that premium models include
  • No kit option available


The Ridgid Octane 4-1/2-inch grinder has the power to be the primary small angle grinder for Pros that don’t need the runtime of corded tools and a supplementary grinder for those that do.

Feature Set

The newest Ridgid cordless grinder benefits from their recent Octane technology. In a nutshell, better electronic communication between the battery and brushless motor allows Ridgid to pull more power than before while still protecting the system from pushing to the point of failure.

Here’s a look at the rest of the feature set:

  • 3-position auxiliary handle
  • Tool-free wheel guard rotation
  • Wheel changes with the included spanner wrench and spindle lock
  • Lock-off protection – the system won’t restart if it shuts down with the power switch on

At this level, there’s not much missing from the basic feature list. There are a few things missing that you’ll find on premium models, though. Hilti has Kwik-Lock tool-free flanges along with Active Torque Control (stops the motor in a bind up). There are also models with an active vibration control and others with an electric brake.

While Ridgid doesn’t claim to have a 2-second brake like some brands, the wheel doesn’t seem to spin as long as some of our other non-braking grinders. It also doesn’t have an obscene level of vibration, either.


I love that Ridgid slims down the handle on this model. For Pros that don’t have gorilla hands, it’s a much more comfortable grip than standard handles. It’s no surprise to find Ridgid’s Hex Grip overmold with its bumpy texture to help secure your grip and improve comfort as well.

Grinders in this size class are pretty manageable on the weight side of things. Without the battery, this Ridgid Octane grinder weighs 4.4 pounds, including the handle. With a 6.0 Ah Octane battery, it bumps up to 6.2 pounds.

With a6.3 Ah Core18V battery, Bosch’s connected grinder weighs 6.1 pounds while Metabo’s WPB 18 LTX 115 is right at 6 pounds with its 5.5 Ah LiHD pack. That puts Ridgid in pretty good company.


Most cordless grinders in this class will be somewhere around 8500 – 9000 RPM. The Ridgid Octane 18V Brushless Grinder moves to the top of the class with 10,000 RPM. It’s a tangible benefit to Ridgid’s Octane boost.

Ridgid Octane Grinder

In this grinder’s case, Ridgid claims a 40% power increase. Our verdict: we believe it. This tool has some legitimate guts, and it’s definitely a lot more powerful than the previous model.

If using a cordless grinder is part of your daily grind, you know that it doesn’t take a ton of pressure to bog one down. It’s still possible with this model, but it takes more effort than other 4-1/2-inch cordless models. More importantly, it takes more pressure than I normally put into a cut or grind even with a corded model.


In case of an overload, an Overload Indicator light blinks red against the power switch. Since you get visual feedback where it’s easy to see, you can ease up immediately and keep working instead of waiting for an overheated battery/tool to cool down before getting back to the grind.


The $119 (bare tool) Ridgid Octane 18V Brushless Grinder has a lot of competition and most major manufacturers make at least one. Here’s how other brushless bare tool prices look for the 18V/20V Max 4-1/2-inch class:

  • Ryobi 18V One+ P423: $99
  • Kobalt 24V KAG424B-03: $135
  • Metabo HPT (Hitachi) 18V G18DBALP4: $159
  • Makita 18V LXT XAG16Z: $169
  • DeWalt 20V Max XR DCG413BL: $169
  • Bosch 18V Connected-Ready GWS18V-45CN: $179
  • Metabo 18V WPB 18 LTX BL 115: $219
  • Milwaukee M18 Fuel Braking Grinder 2783-20: $229
  • Hilti 22V AG500-A22: $339
Ridgid clearly rules the roost in bare tool price aside from its Prosumer Ryobi cousin. There’s no kit option to give you a break on the battery/charger price, but a grinder isn’t your normal entry into a cordless platform unless it comes in a combo kit.

The Bottom Line

The Ridgid Octane 18V Brushless Grinder has the power to go toe-to-toe with anyone’s cordless 4-1/2-inch grinder at a much lower price than premium models. The trade-off is that you’ll miss out on a few features that premium models have.

Ridgid Octane 18V Brushless Grinder Specifications

  • Model number: R86042B
  • RPM: 10,000
  • Weight:
    • 4.4 pounds (Bare)
    • 6.2 pounds with auxiliary handle and 6.0 Ah Octane battery
  • Warranty: 3-Year Limited and Lifetime Service Agreement
  • Price: $119 (Bare)
  • Available: Early 2019



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