Professional Tool Reviews for Pros

Ridgid Octane 7-inch Grinder Review

Ridgid Octane grinder trailer
PTR Review
  • Pro Review 8.3

Ridgid's first crack at a 7-inch grinder is an unquestionable success, especially if you emphasize cordless power over all else. While its size and weight make it ill-suited as a 4-inch grinder replacement, this 7-inch grinder has the power for handling industrial trades.

Overall Score 8.3 (out of 10)

The Ridgid Octane 7-inch Grinder can run on standard Ridgid 18V packs, but the Octane platform gives it beastly power. But power isn’t the only thing beastly about the Ridgid R88040B – look at the size of the thing! Here’s what we’ve found out about it during our daily grind.


  • Lots of power on two Octane batteries although it can run on one Octane or two standard Ridgid 18V packs
  • Rotating grinding head and 3-position auxiliary handle for safe and comfortable operation
  • The grinding head is weighty enough to avoid bouncing during operation
  • Easy, tool-free guard rotation is excellent
  • Quick wheel brake


  • It’s big and heavy compared to a 4-inch grinder
  • There was a little play between grinding head and power base at the point of pivot
  • Pivot buttons were especially hard to push
  • Noticeable delay on spin-up


There’s no denying that a cordless 7-inch grinder with this much power is impressive. But you don’t want this to fill in for your 4-inch grinder—it’s just too big and heavy. Still, there are comfort and safety advantages to the rotating head, three handle positions, and easy-to-rotate blade guard. There is a short delay on spin-up which occurs each time you pulled the trigger. Ultimately, you can get a lot of work done with the Ridgid R88040B Octane grinder.


Back to the Grindstone

Before the Ridgid R88040B 7-inch Grinder’s wheel completed one revolution, our crew was apprehensive about its heft. It’s especially heavy with two Octane batteries inserted. The apprehension turned into a conversation about what tasks and which tradespeople the grinder best suited. Suddenly, the R88040B made a lot more sense. Perhaps you caught PTR’s interview with Kevin Gee, Senior Product Manager at Milwaukee (Ridgid’s cousin) a while back. Mr. Gee said 7- to 9-inch grinders are at home in shipyards and gas/oil industries where long, tough cuts and grinds are the norm.

Ridgid Octane angle grinder

That’s significant for a couple of reasons. First, contractors, MEP Pros, and industrial fabricators shouldn’t think this grinder replaces 4- to 6-inch tools. Neither should they dock it points for its size, especially given the monstrous amount of power it produces. It also shows Ridgid’s confidence in the Octane platform.

Ridgid Octane 7-inch grinder plate

We put the grinder to work at our shop before we even brought it to a job. First, we began the repairs on some trailer rust damage. Next, came a good deal of grinding on masonry—cutting it to fit or removing it. The Ridgid didn’t break a sweat! Since then, it’s been hard at work for our customers with equally impressive results.

Ridgid Octane 36V grinder

Handle It

The Ridgid Octane 7-inch Grinder mitigates its size/weight with a 3-position handle and a grinding head that pivots around the power base. It’s a design reminiscent of the MegaMax we reviewed a while back. In this case, however, the tool head is not interchangeable. Unfortunately, the button that allows it to pivot is very hard to push (and there are no slouches on our crew!).  There’s also a little bit of play between the head and base which we’re not crazy about.

Ridgid 7-inch grinder handle

However, the handle positions and the pivoting head make for safer, more comfortable operation—something we really liked.

Rubber meets the Road

Two things bugged us about the Ridgid Octane 7-inch Grinder. They are obviously worth mentioning but don’t break the deal. First, there’s a small separation where the front, bottom part of the handle approaches the power base’s body. This is a recipe for snags and peeled-back rubber.

Ridgid Octane 7-inch grinder handle

Second, our crew members sense a slight spin-up delay when they pull the trigger. This might be Ridgid’s intention for safety reasons due to the centrifugal force of the large wheel. But it doesn’t mimic the familiar feel of a corded grinder. Kevin Gee, in the interview we referenced above, said that brushless motors allow manufacturers to replicate a corded grinder’s feel by manipulating the spin-up speed.

Ridgid Octane grinder guard


At $244 for the bare tool, the Ridgid Octane 7-inch Grinder is priced competitively. Here’s a look at the small field:

  • Makita 36V 7-inch Grinder XAG12Z1: $154.99
  • Ridgid Octane 7-inch Grinder R88040B: $244
  • Milwaukee Fuel 7- to 9-inch Grinder 2785-20: $210.00 (kit)

Ridgid R88040B Bottom Line

After hours of powerful grinding and cutting, this tool has grown on us. Ridgid’s first crack at a 7-inch grinder is an unquestionable success, especially if you emphasize cordless power over all else. Its size and weight surpass what a smaller 4-inch grinder can tackle. Other than a couple of design hiccups, we consider this tool a great option, particularly with no outlets nearby. There’s no doubt the Octane platform—and this 7-inch grinder—has opened up Ridgid tools to more trades like oil/gas and shipyard work. Ridgid has accomplished all of that at an excellent value.

Ridgid Octane 7-inch grinder

Ridgid Octane 7-inch Grinder Specifications

  • Model: R88040B
  • Dimensions (HWD): 7 x 13 x 24 in.
  • Arbor: 5/8 – 11 UNC
  • Electronic speed control
  • Paddle switch
  • Maximum speed: 6900 RPM
  • Brushless motor
  • Adjustable handle position
  • Lock-on switch
  • Variable speed
  • Weight: 8 lbs.
  • Price: $244 (bare tool)

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Frank D

What kind of blades does it use? I returned their corded model prior to this release, as it simply only cut an extra 1/4” over my old 4” grinder / cutter because of the big center locking arbor and it failed to center and clamp a brand new stock standard 7” diamond masonry cutting blade without stacking a series of washers inside … The ridgid was only designed to hold discs with that flange in the middle for grinding. Had a chat with a product representative. This was intentional. It is not meant for cutting due to safety, only for… Read more »

Mark Griffin

That has to be the most awkward grinder I’ve seen yet. Honestly it doesn’t even look functional as serious grinder

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