I tested the fully decked out I-Set kit (#575707). It comes with two 18V Bluetooth-enabled batteries, rapid charger, AC adapter, 13-foot Plug-it power cord, long-life dust bag, wrap-around bum­per and SYS-COMBI 2 Systainer. The AC adapter enables you to plug the sander into a standard 120V electrical outlet when porta­bility isn’t needed or when you’re doing a lot of sanding and don’t want to bother with constantly recharging the battery. There’s also an I-Plus model (#576367) that doesn’t include the AC adapter and extension cord for those of you who eschew corded tools of any kind, and a bare-tool basic model (#576358) for those who already have an Ergo-I 18V battery. You can’t use standard Festool batter­ies with the DTSC 400 (though you can use any Festool charger). The reason is that the low-profile design of the sander necessitated a longer battery that slides into the tool’s handle rather than sitting atop the sander.

With the 18V 3.0Ah battery installed you get 30 minutes of continuous runtime at full power – somewhat longer if you step down the speed. The brushless motor delivers an orbital sand­ing motion with a 5/64″ stroke and dial-selectable speeds from 6,000 to 10,000 oscillations per minute. The short sanding stroke delivers a very fine finish with a scarcely perceptible scratch pat­tern. Sander speed is controlled with a six-speed dial. There’s also a series of micro settings between each dial position that enable you to step up the speed in small increments. Thanks to electronic speed control there is no loss of speed under load – just consistent sanding from start to finish.

The DTSC 400 stands 6″ high and with either a battery or AC adapter installed weighs in at just over 3 lbs., 4 oz. It’s coupled with a nicely balanced design and rubberized grip, and I found that I could easily control the sander with one hand and use it for extended sanding sessions without undue hand or forearm strain. I don’t think it would be too awkward to use on vertical surfaces, either. When sanding the insides of cabinets there is sometimes a tendency to butt the sander up against adjacent sides. The included edge protector prevents this from happening.

Dust collection is fabulous – the best that I’ve seen on any sander. In addition to the holes in the bottom of the sanding pad (common to virtually all sanders), there are a series of small dust extrac­tion ports along the sides of the sanding pad that suck up dust and deposit it in the dust bag. The dust bag is quick and easy to empty and looks like it will last quite a while before needing to be replaced. You can, of course, connect a Festool dust hose to the sander. And if you have a Festool Bluetooth-integrated dust extrac­tor it will start automatically when the sander is switched on.

At its lowest speed I measured the sound level at about 68 deci­bels and around 79 decibels at the highest speed setting, which is comparable to other sanders I’ve used. Vibration is minimal at the lowest speed setting but more noticeable at the highest set­ting, though in my experience, still within a reasonable level for a sander.

In use, the DTSC 400 delivered consistently superior results. Dust extraction is as good as you can get. Coupled with its light weight and ergonomically designed barrel-style grip it’s super comfortable to use.

If you’re looking for a dependable pro-quality finish sander, you can’t go wrong with the Festool DTSC 400.

Keep It Clean – Not only is the dust bag easy to remove, it works very effectively as part of Festool’s extensive dust collection system. Notice the installed edge protector that keeps the sander away from any edges when needed.

Dual Power Sources – We generally all enjoy cordless power when possible, but there are times when connecting to a power source is the best approach. An AC adaptor is available that will connect the sander to constant power, if needed. The battery is also Bluetooth-enabled, automatically turning on your Festool dust extractor when the sander is turned on.