Flex 24V Online Circular Saw Wears Its Thin Belt
Flextronics breaks into the professional cordless power tool space with an impressive lineup of first-generation tools. While many of them tick the core tool boxes every Pro needs, the Flex 24V 6 1/2-Inch Inline Circular Saw is something else entirely.
advantage
- Comfortable Ergonomics
- impressive cutting speed
- Significantly improved right vision
- 7 1/4" saw depth of cut
- Includes vacuum hose adapter
- 5 Year Warranty (Register before 12/31/22 to extend to Lifetime Warranty)
shortcoming
- no obvious disadvantages
Flex 24V Inline Circular Saw Performance
First off, yes, it's a very different design. We'll take a closer look at that later. Now, let's start with performance. After all, who cares about design if it can't be cut?
We put this circular saw to the test in our shop and pushed it to the limit as hard as we could. In addition to a series of test cuts, we also put it to the test on the PTR circular saw test track.
Test runway parameters
If you're not familiar with the setup, here's what this test track looks like:
- Crosscuts: Five crosscuts (2 x 10)
- Bevel Cuts: Five 45º beveled cross-cuts (2 x 10)
- Miter cuts: Five 45º miter cuts (2 x 10)
- Compound cuts: Three 45º miter/45º bevel compound cuts from each side of the wood (6 cuts total, 2 x 10)
- Power drive: One 4' breach (double 3/4" OSB subfloor)

The saw is obviously not as strong as the Flex's standard-design 7 1/4-inch saw, but it's no slouch either. It finished with a time of 2:10, well behind its 7 1/4-inch rival at 1:36. When you look at saws that were done before the inline model, they all used larger batteries to gain that extra muscle. It hangs in the best place compared to a saw that sticks with a more traditional single battery.
The good news is that it was able to do all of our cuts with a high degree of confidence. You'll need to slow down a bit to keep the RPM high on miter and compound cuts, but we wouldn't shy away from cutting anything with a 7 1/4" saw.

Flex 24V Inline Circular Saw Design Notes
Consequences of inline design
We really like the idea of an online circular saw. When you're cutting, it almost feels like a backhand saw, but there are some major differences mechanically. The slim profile houses a sensorless brushless motor that powers the saw's unusual belt drive.

Belt drives differ not only in cut feel, but also in depth. With its 6 1/2-inch blade, this saw has an impressive 2 9/16-inch depth of cut—the same as many 7 1/4-inch saws we use, enough to cut 3 times in one cut.
In addition to the depth of the cut, the shoe is much slimmer than other designs. It has the typical left side sight of a left blade saw, but the right side is noticeably better. It's the closest thing to a circular saw that meets both preferences we've seen.

One thing to note is that the bevel range is a maximum of 47°. This isn't the only saw with that limit, but many reach 56°, and it's worth mentioning.

Despite its compact design, don't mistake this saw for a DIY goal. It feels like it can handle the job site environment as well as most of the Pro brands we use.
size and weight
Due to its smaller size, we expected this saw to weigh less than the full-size model, and it did. The bare tool weighs 7.1 lbs, while the 5.0Ah battery makes it 9.1 lbs. Anything less than 10 pounds is solid for a cordless saw, although it's not as light as some of our other 6 1/2-inch models.

The main handle fits my medium hand perfectly and the side handle is a good size. It's a bit closer to the main handle compared to a full-size saw, but that's what we've come to expect from a compact design.

With a 5.0Ah battery, the overall balance is just right.
Additional features
- collapsible rafter hook
- Built-in hex key storage
- LED work light
- vacuum hose adapter
- Compatible with the entire Flex 24V system
The Flex price for this saw is $249.00 at Lowe's. It comes with saw, 5.0Ah battery, 160W fast charger, blade and carrying bag. As we write this, there is no bare tool option.
Flex tools come with a 5-year warranty. If you register your tool before 12/31/22 they will extend it to a lifetime warranty.
the bottom line
Flex has figured out a way to give you excellent visibility from both sides of the blade and give you the cutting power of a 7 1/4" saw to a 6 1/2" circular saw. No other circular saw we've tested can do this, and it's powerful enough to rank among the top compacts. If you're looking for a cordless compact circular saw, there's no better overall package than the Flex 24V 6 1/2" Inline Circular Saw.
Flex 24V Inline Circular Saw Specifications
- Model: Flextronics FX2131A-1C
- Blade Size: 6-1/2"
- No-load speed: 5,500 RPM
- Bevel Capability: 0-47°
- Arbor: 5/8 inch
- 90° Cutting Capacity: 2-9/16"
- 45° Cutting Capacity: 1-9/16"
- Tool Weight (Bare): 7.1 lbs
- Tool Weight (with 5Ah battery): 9.4 lbs
- Price: $249 with 5.0Ah battery, fast charger, blade, and case
- Warranty: 5 years (Lifetime after registration on 12/31/22)
For more information on the complete Flex 24V range click here