DEWALT FLEXVOLT™ 12 Inch 120V Miter Saw Review

Tool Box Buzz rating:

FLEXVOLT™ 12 Inch 120V Dual Bevel Compound Miter Saw DHS790AT2

FLEXVOLT 120V 12" Miter Saw

4.5/5
Manufacturer: DEWALT
Model number: DHS790AT2
Price: $799
Power source: 60V Lithium Ion
Motor size: 15 Amp
Weight: 56 lbs
Last year when DEWALT revealed their new FLEXVOLT™ line of cordless tools we were excited and a bit skeptical about how well this new 12″ full size miter saw would perform on the job. We’ve spent the last 6 months evaluating this new miter saw with two different crews building a new house and also on remodeling jobs. This long evaluation process has been a long wait for our readers, but we feel like we’ve been able to fully vet this amazing new saw.

DHS790AT2 Features & Specifications

  • Flexible power options – corded or cordless – this saw can run off battery power and AC corded power.
  • Accuracy cutline blade positioning system and highly visible miter and bevel scales
  • Portability – Compact design weighs only 56lbs.
  • 12 inch diameter blade
  • 1 inch arbor
  • Max cut thickness 6-3/4″
  • Max Degree Miter Left and Right: left 50 Right 60 degrees

Variable Power Options – AC and DC Power

The first and most important feature of this saw has been the ability to use it as a cordless saw when we had no power, to eventually switching over to running it plugged into the AC power source. The DHS790AT2 is designed to run off (2) FLEXVOLT 60V battery packs, or you can run it on AC power by simply installing the convertor that plugs into the battery pack sockets. Because the saw is running on 120V from the battery, the conversion to run off 120V AC is fairly simple to do (we REALLY wish they would do the same thing on the FLEXVOLT Table Saw!).

This option makes the new FLEXVOLT miter saw one of the most versatile cordless tools we’ve ever used. Having this type of option available to high demand tools like a miter saw allows users the maximum amount of flexibility to get the job done using one tool.

Job Site Performance – FLEXVOLT Miter Saw

In order to get a real grasp on the overall performance of the new DEWALT FLEXVOLT 12″ Sliding Miter Saw we’ve spent over 6 months evaluating the saw on both new construction and remodeling projects. My crew has been using the saw since August on a new house build on a lake here in NH. We started using the saw for the beginning stages of framing the house walkout basement when there was no power on site yet, and we used the saw all the way to the finish stages when power was available in the house.

What stands out most about this miter saw is how well it performs in both cordless and corded modes. There is no noticeable difference in performance from one mode to the other, and the saw performs just as we’d expect from experience using our other 12″ DEWALT miter saws over the years.

While framing the walkout basement on this project, the crew was able to cut framing lumber all day using just two battery packs (two are required to run this saw). The batteries were plugged in during lunch break to give them an additional 30 minutes of charge time, but I’m not even sure that was needed. The saw has plenty of power for cutting framing materials including engineered lumber, even when running in the cordless mode.

Precision and Accuracy

We found the DHS790AT2 to be very accurate right out of the box. No adjustments were needed for the miter or bevel factory settings which was a nice surprise. After six months of use we continue to be impressed with the saws accuracy and precision even though we use it for both rough framing and finish work. We’ve used the saw cutting exterior trim, decking, interior oak stair treads, and interior trim with great success. Again, I’d compare this saw to any of the DEWALT saws we’ve been using on the job for years.

Packed with Features

The DHS790AT2 is packed with all the features that you’d expect from a quality miter saw. Our favorite feature is the cutline blade positioning system (shadow line) that DEWALT has been offering for quite some time. We like this system much better than older laser systems because it accurately reflects the width of the blade being used. The miter controls and detents work flawlessly and are easily adjusted if need be. Lastly, the blade guard that DEWALT uses is one of the best in my opinion. It works smoothly and never gets hung up like some of the other guards on the market.

Run Time

We found run time for this new saw to be really good. In a run time test we performed last summer we were able to cross cut 124 times in a SPF 2×12. This test was performed using (2) 60V 6.0 Ah FLEXVOLT battery packs. The test involves cross cutting (at 90 degrees) the 2×12 every 10 seconds for a total of 10 cuts. Then the saw is allowed to rest for 1 minute. Then another 10 cuts are made, followed by another rest. We feel this is the best way to simulate actual use on the job. Obviously, with the new 9.0 Ah battery packs that were just released this month, the run time will be even greater.

In job site use, we found the saw had plenty of run time to keep up with the crew throughout the day. If a crew had one extra set of batteries, they could work all day even under the most demanding applications.

Suggested Improvements

This saw is really good and doesn’t have much in the way of issues that we found to be noteworthy. I would like to see DEWALT explore options to allow for bevel adjustments near the front of the saw instead of having to reach around the saw to control the bevel settings. While that might seem like a minor issue, we think it’s an important design issue that makes a miter saw safer and much easier to use, especially if you make lots of bevel cuts.

A larger issue that we have discovered with the FLEXVOLT miter saw is an electrical interference issue. While doing finish work in the new house we’re building for a client we discovered an issue that we’re hoping DEWALT can resolve in the near future. When plugging the saw in using the AC adapter it is causing breakers to trip in the electrical panel of the house. What’s really strange is the fact that it’s not tripping the circuit that it’s directly plugged into, it’s tripping other dual function AFCI/GFCI breakers in the panel. This must be an issue with the converter and signals it’s sending through the electrical system. Needless to say it’s a nuisance that’s not fun to deal with, and one that customers are likely be be annoyed with when doing renovation and remodeling work. We’ve reached out to DEWALT hoping they can address the problem.

Update: We’ve been in contact with the design team at DEWALT and they are aware of the issue. They are working on identifying the issue and working on a possible solution. We’ll keep you posted as things develop. The tool was tested heavily for use with GFCI protection, but may not have been evaluated for recent developments and requirements for AFCI (Arc Fault) protection.

DEWALT FLEXVOLT Sliding Miter Saw Video Review

Overall Impression – DEWALT FLEXVOLT Sliding Miter Saw

The last year or so we’ve seen cordless miter saws of several sizes make their debut and the results have been very impressive. However, none of them have been a full size 12″ saw and none of them has the option to be plugged in directly to an AC power source as well as being cordless. That has all changed now with the introduction of DEWALT’s new 120V FLEXVOLT 12″ Sliding Compound Miter Saw.

The DHS790AT2 is the best full size miter saw for job site applications in our opinion. Offering all the features of DEWALT’s 12″ sliding compound miter saws with the option of running cordless it’s hard to compare it to any other miter saw on the market. Run time is excellent and the power it offers in the cordless mode doesn’t appear to be any different than when plugged in directly. With the recent availability of 9.0 Ah battery packs (we did our evaluation with 6.0 Ah packs), the saw will offer even great run time and versatility. We feel the $799 price is fair for a quality saw like this that offers such amazing flexibility for contractors.

One issue that must be considered however is the fact that users must upgrade to a new battery platform to run the FLEXVOLT miter saws. This saw only runs on the 60V battery packs and will not run on older 20V packs. For some users this will leave them feeling a bit left out from all the 20V packs they have invested in.

If you’re in the market for a full size job site miter saw then look no further. This is the saw you can put in the job trailer and use it in any situation and have no need for a generator. This would be a 5 star review except for the slight glitch we experienced with the electrical panel. Hopefully that gets resolved soon and this saw becomes the gold standard.

FLEXVOLT 120V 12" Miter Saw
$799

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About the author

Todd Fratzel

Todd Fratzel is the Editor of Tool Box Buzz and the President of Front Steps Media, LLC, a web based media company focused on the Home Improvement and Construction Industry.He is also the Principal Engineer for United Construction Corp., located in Newport, NH. In his capacity at United he oversees the Residential and Commercial Building Division along with all Design-Build projects.He is also the editor of several other sites including: Home Construction & Improvement and Today's Green Construction

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3 Comments

  1. Glass

    The 780 will trip arc breakers as will many power tools not just this saw. Any appliance can trip an arc fault breaker, even a loose neutral on another breaker could trip an arc fault.

  2. Glass

    Just to follow up if arc breakers are tripping and the appliance is not plugged into said breaker it is a wiring problem, maybe common neutrals etc… or older arc breakers where problematic.

    1. Todd Fratzel

      Actually it’s not a wiring issue. DEWALT is working on the issue now. It has something to do with the brushless motor (something we don’t typically see in a plugged in tool), and the converter. None of the other power tools on site are tripping the breakers. We’ve got compressors, table saws, and even other miter saws running with zero problems. It’s actually tripping the dual function AFCI/GFCI breakers, and we’re not even plugged into that circuit.

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