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"A bad worker quarrels with his tools"

Published: Feb 15, 2011
Updated: Apr 14, 2011 - added video of edge sanding

Festool RO 90 DX Rotex Sander

Possibly the only sander you'll ever need.

$375 from Amazon.com or any other Festool dealer

Note: This tool was provided free of charge by Festool USA for the purpose of review

In January 2011, I was given the opportunity to preview Festool's brand-new RO 90 DX Rotex sander, about six weeks before the official USA release. This review is based on about two weeks of experience on several projects. The RO 90 DX was tested with a Festool CT 26 E dust extractor.

Throughout this review, I'll simply refer to the RO 90 DX as the RO90

What's in the box

Click on the image to the right for a video tour of what comes with the RO90.

First off, the RO90 comes in Festool's new T-Loc Systainer. While it took some getting used to, I really like the new design. I'll be taking a closer look at it in a separate review.

The Systainer insert holds the sander with its standard accessories, with room for extra pads and protectors. There's also spots for storing delta and round abrasives, a few dozen sheets of each.

The RO90 comes with a standard Festool Plug-it cord, a round hook-and-loop pad, a delta hook-and-loop pad, and an edge protector. It also comes with an assortment of round and delta abrasives. While it will most likely change in the future, my pack had five round and five delta sheets each of Granat in P60, P80, P120, and P220. It also had three round P40 Granat and two round Vlies pads (A100 & S800), as well as five delta sheets of P40 Saphir.

I was concerned about doing this review with such a small sample set. While the delta pad uses the same size abrasives as the DX 93, the 3.5" round abrasives are unique to the RO90, so I can't just run down to WoodCraft and grab some. However, the abrasives last an extremely long time, so it never became an issue.

Features and controls

Click on the image to the right for a video tour of the RO90's features.

Let's start with the back of the RO90. A standard Festool Plug-it power connector and dust port allow you to quickly switch between tools by just moving the same power cord and hose between tools.

The RO90's speed control is located on the left-rear underside of the handle. The dial is recessed and well-protected from being changed accidentally during use. In fact, it's so recessed that the fat-fingered among us may have a little difficulty accessing it. If I could choose one thing to change on the RO90, I would make this opening around the dial a little wider and/or the dial a little thicker.

The RO90 uses a stepless electronic speed control. The intelligent control system features a soft start, reducing the load on the motor (and your hands). It also monitors the sander's performance, keeping the pad speed constant despite varying pressure or material consistency. It'll also reduce the power to the motor if it senses the sander beginning to overheat and will shut down completely before the tool is damaged from an overload.

The head of the RO90 has two on-top controls. The power control is a simple front-back slide switch, easily used by right- and left-handers. This switch is extremely easy and intuitive, far superior to the clumsy rocker switches used on the other sanders I own. The other control is a three-position rotary dial. Festool calls this a "change over switch" but I'm just going to call it a "mode switch". The dial is used to put the sander into Rotex, random-orbit, and delta modes. The dial must be pushed in before turning to delta mode. More on the modes and their uses later ...

Installing a sanding pad is a simple, tool-free operation. Make sure the sander's mode switch is in delta mode, then push the pad onto the sander and twist the pad clockwise. The delta pad has a locking plunger that will snap into place (since round pads rotate, they're self-tightening).

To remove a sanding pad, again making sure the mode switch is in delta mode. For round pads, turn the pad until it snaps into the locked position, then twist the pad counter-clockwise to remove it. The delta pads never turn, so they're already in place, just push the green plunger to release the lock, then turn the pad to release.

One important safety feature is a locking pin on the underside of the sander. When the sander is put into the rotary modes (Rotex and random-orbit) this pin rises out of the body. When the delta pad is on the sander, it blocks this pin from rising, which means you can't mistakenly set the sander to a mode that would spin the delta pad, turning it into an electric-powered ninja weapon.

The RO90 also incorporates a pad brake, which stops the pad motion pretty quickly when the power is turned off. The RO90's pad completely stops in almost 1/3 the time of my other sander. It may not seem like much, but when you turn off the RO90 and go to set it down, it's generally stopped by the time it reaches the table. Waiting for the sander to stop so you can set it down gets irksome after a while. A small feature, but greatly appreciated. Click on the image to the right to see a video on how quickly the RO90 stops moving.

Dust collection

Dust collection (or extraction) is a core principle of all Festool products. As more information about the long-term health dangers of dust exposure comes to light, collection and containment of wood dust is more than just a matter of convenience.

The RO90's pads incorporate their Jetstream technology, where outside air is allowed to flow from the center of the pad (as well as from the outside) to the collection holes which are placed near the edge. This contrasts with a typical sander, where a single set of holes nearer the center of the disk are mostly pulling from the outside, while basically balancing each other out in the center, see the first photo for a diagram of the airflow. The second photo shows a comparison of the results of the dust collection of each system. Each sander was run for about 15 seconds. I didn't have any dark abrasive for the RO90 and I didn't have any light-colored paper for the 5" sander, so I sanded some ash with the dark paper and some cocobolo with the light paper. As you can see, the RO90 paper is virtually spotless, while the standard paper is already clogging up. The Jetstream system not only keeps the work area clean and the paper unclogged, it also keeps the paper cooler for longer abrasive life. Wood dust that's allowed to stay on the paper generates and traps heat, eventually bonding right to the abrasive and rendering it useless. Cool, clean paper lasts longer and cuts your costs.

Note that Jetstream does not pump air into the center, instead the suction from the outer holes creates a vacuum that pulls air through the center hole, which leads to three channels spaced around the top of the round pad. One of these channels is shown in the photo. The delta pad uses a different version of the Jetstream system. Here, the inlet is located in the top center of the pad.

Three sanders in one

The RO90 is definitely not a one-trick pony. The mode switch gives you, essentially, three capable sanders in a single unit. Click the image to the right for a quick video demonstration of the three modes and how they affect the behavior of the sanding pad.

In detail mode, the RO90 becomes an excellent tool for sanding in corners. It removes material very quickly, in fact there was a learning curve for me to not sand right through thin veneers or dish out corners. Festool claims the RO90 removes material more quickly than similar tools like the Fein Multimaster because it uses a true orbital motion instead of a sweeping arc-shaped motion. Whatever the reason, it's definitely an efficient tool in corners.

The delta pad is the same size/shape as the Deltex 93, so all the same abrasives will fit the RO90. The abrasives and pad are equilateral triangles, so if you wear out just one corner or edge of the abrasive you can just rotate the paper for some fresh grit. Likewise, if the front tip of the sanding (interface) pad becomes worn or damaged, you can just rotate it instead of replacing the entire pad.

It's worth noting that the sides of the delta pad are not straight, but convex. The virtually eliminates the tendency of the pad to "bounce" off the sides of a corner. I'm guessing that since only a small length of the pad comes in contact it can't return much of a push, it just squishes.

The dust collection efficiency of the delta mode is not as good as the round pads, quite a bit of dust is left in corners. It seems to be inherent to the design of the pad. I used both the round and delta pads to sand an open area, keeping the RO90 in delta mode with both pads. As you can see in the photo, swiping the sanded area with my fingers shows a lot more dust left behind. Now, I'm not saying the dust collection of the delta pad is bad, in fact it's quite good. It's just that the Jetstream system on the round pads is so phenomenal, it makes the delta pad look bad by comparison.

Switching the RO90 over to random orbit mode gives you a very good finish sander. As I showed earlier, dust collection is superb. The sander tracks well and it's easy to control. When sanding near an edge like a floor where it meets the baseboard, the included edge protector keeps the edge of the abrasive from running into and scarring the other surface. In most ways, it's a typical random orbit sander, so there's not a lot to say than it does the job very, very well.

Of the three modes, I find the Rotex mode the most intriguing. At first glance, it appears to be just another random-orbit mode. But a closer look reveals that it's very different. When switched into Rotex mode, the RO90 engages a gear drive that turns the pad directly, like an angle grinder. But, since the RO90 also imparts an eccentric oscillation (like the path of a Spirograph) to the head, you don't get the deep circular scratches like you would with an typical angle grinder or sander. The Rotex mode removes an amazing amount of material in a very short time (if you click on the image to the right you can see a video of how quickly the RO90 can dish out a piece of birch plywood). And the surface it leaves is surprisingly uniform and smooth, taking it down to a final finish is not as much work as you might expect given how quickly it removes material.

Having all this capability in one tool is very handy. In Rotex mode, you can smooth a rough surface, strip an old finish, or carve a curve. The, by flipping a switch and changing the abrasive on the same tool, you're laying down a silky smooth final surface. Flip the switch again and change the pad, now you're finishing off those tight corners. Click the image on the right for a video of the RO90 stripping off thick latex paint, then sanding to a final surface.

Initially disappointing, ultimately wonderful

To be honest, when I first started working with the RO90, I was disappointed. I found it clumsy and difficult to control when sanding horizontal surfaces. The center of balance is not over the head, as I was used to, but towards the rear, which was exacerbated by the weight of the power cord and dust extractor hose. This made the the sander very tail-heavy. Sanding vertically was no problem, since I wasn't fighting to keep the pad horizontal.

However, I found that just shifting the way I held the sander completely changed it's behavior. Instead of holding the official "handle" of the RO90, I found that holding the rear of the sander (grabbing the power plug and dust port) with my right hand and putting my left hand on the head, the RO90 was now very easy to control and would smoothly glide over the wood. I could also get an easy-to-control sander by looping the power cord and hose over my shoulder. The real issue (for me) was the weight of the power cord and hose. I think the Festool Boom Arm accessory for their dust extractors or some other way to hold the hose weight off the sander would be a very effective addition for the RO90.

Ultimately, though, once I had some more time actually working with the RO90 I adjusted and learned different ways to hold it one-handed. The problem wasn't so much the balance of the RO90, it was my inexperience with this style of sander. If you get the chance to play with it at a demonstration and it feels odd, keep my experience in mind. And don't forget Festool's awesome 30-day no-questions return policy!

Now that I've had more experience with the RO90, I find that I vastly prefer it to my old sanders. The RO90 provides a much more pleasant sanding experience. This stems from a variety of factors, some objective, some subjective.

For one thing, it's much quieter. My other sanders measured between 90 and 105 dB, while the RO90 (in random-orbit mode) was between 78 and 87 dB, depending on the speed (and including the noise of the CT26E). Keep in mind that a 10dB difference is perceived as being twice as loud, plus 85dB is the point where prolonged exposure can cause hearing damage. In other words, the loudest the RO90 ever got was still quieter than any other sander could manage and it's almost completely operating in the safe zone, while the other were well up into the danger zone. Even with the RO90 and CT26E turned all the down, sanding and dust collection were very effective and so darn quiet. And it's not just the noise level, it was also the quality of the sound. The RO90's sound is lower-pitched and less "buzzy" than the others. A big-block V8 and lawn mower engine might measure the same sound pressure level, but one sounds much less irritating than the other.

The vibration of the sanders is also quite different. I don't have any way to objectively measure the vibration levels, but subjectively the vibration level of the RO90 is less than the others, especially at lower speeds. And, after sanding for an extended time, the RO90 is far less likely (if at all) to leave me with tingly hands.

Even more unpleasant than vibration is the dust raised by power sanders. As I noted earlier, dust collection in the Rotex and random-orbit modes is outstanding. Even in delta mode, while not as good as the other modes, the RO 90 doesn't let that much dust get away. It just looks bad in comparison to the other modes.

With its 3.5" pad, compact size, and light 3.3lb weight, the RO90 is terrific for working small areas where larger sanders simply won't fit. I was dreading sanding the old finish off our front door, an 8'x3' mahogany beast with multiple small recessed strips where my 5" ROS couldn't go. I was faced with sanding it by hand or getting vibrated to a tingling pulp by my 1/4-sheet sander. The RO90's small head zoomed right into the tight zones and the delta head made short work of the corners. It even did a descent job of the multilevel mouldings, although I found myself thinking a lot about Festools LS 130 linear-stroke sander that I'm pretty sure would have worked better.

The RO90 excelled at edge-sanding. Sanding a 3/4 or 1/2" edge can be an adventure using my old 5" ROS, keeping it level and not rounding over the corners is challenging. The RO90, however, handled like a dream for this task, giving me a perfect finish and razor-sharp edges. The larger sander also has a bad tendency to grab the edge and yank the sander sideways, so that I'm always struggling to keep it on track. The RO90 would just glide back and forth with very little of this sideways pulling. I think the small pad size contributed greatly to this stability and performance on edges. UPDATE: A couple months later I needed to sand a burn off an endgrain edge of cocobolo and caught it on video to show how well-behaved the RO90 is when aggressively sanding an edge, click the image on the right to see it.

The only sander you need? Maybe ... but probably not

The RO90 is an amazing multipurpose sander. However, I have to disagree with those who claim that it eliminates the need for owning any other sander.

The small pad size, which makes sanding in tight spots possible and (I believe) gives the RO90 its amazing edge performance, is a liability in sanding large areas. A 6" round pad has three times as much abrasive as the 3.5" pad on the RO90 and would be much faster at doing big stuff like tabletops, shelves, etc.

Also, the RO90 has a 3mm (1/8") stroke, which is neither as fine as the 2mm stroke of their best finish sanders nor as aggressive as the 5mm stroke of the ETS 150/5 or RO 150. Both would have an advantage over the RO90 in some situations.

However, if your needs match the RO90's specs, it's an amazingly versatile sander and could very well work as do-it-all sander, especially considering the light weight and compact size. Even more so if you primarily work with smaller projects. I think it would be an excellent complement to the other sanders in the Festool line, perhaps as an companion to an ETS-class sander. It would definitely be an excellent first step into the world of Festool sanders, as it was for me. It was a real an eye-opener on how good a sander could be and has me lusting after an ETS 150. Although I'm still eyeing that LS 130 ...

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