New Tool Review: Mirka DEROS 550X Random Orbital Sander

Photos by author

It costs $595. I wanted to get that out of the way up front, so it’s not a “buzz kill” when you get to the end of this article, because nearly everything else that I will say about this sanding system will make some design engineers at Mirka blush. For many WWGOA readers this sander might not be a contender for budgetary reasons, but for those shops who demand extreme performance from their tools, or those who have the discretionary income to go “top shelf” on tool purchases, you will want to take a look at this sander. It provides outstanding power with minimal heft, along with low vibration that allows for fatigue-free extended use. Add to that dust collection that is so effective that I might be tempted to use it without a mask, and you have a tool that promises to change the rules in the world of random orbital sanders.

Full system. The sander can be purchased separately, but it is designed as part of a system that includes a dust extractor as well as special abrasives that are designed for greater longevity and dust extraction. I brought in a complete setup for the purposes of these tests.

Why is this such a big deal?

The Mirka DEROS (stands for Direct Electric Random Orbital Sander) is the first random orbital sander with a brushless DC motor that has the power supply efficiently incorporated into the sander body. The motor delivers far more power than any typical electric random orbital sander that I have ever used, and I’ve tried most of them. The DEROS actually rivals the power found in pneumatic sanders, which are generally far superior in performance to their electric counterparts.

At only 3-1/2” tall, and 2.2 pounds, its petite profile makes the tool manageable in any sized hand, much like a pneumatic sander. I found its light, compact form to be particularly beneficial when sanding vertically, which can be tiring using typical electric random orbital sanders.

The soft-start feature delivers a gentle ramp-up to peak performance which, coupled with silky smooth ongoing operation (even with aggressive grits), makes sanding a more pleasant experience. Variable speed control built into the trigger mechanism provides smooth, single-handed speed changes which gives the operator exceptional finesse in moving across intricate areas of a project.

Extreme power!

I had a lot of fun putting the sander through some extreme tests to see where the power advantage would reveal itself. I took a gnarly rough-sawn walnut plank, 6” wide x 6’ long, and sanded it until all tool marks were gone using an 80 grit disk. I was actually somewhat surprised when this task was complete in only a few minutes. I did this several more times on smaller planks of various species and continued to be impressed with the rate of stock removal. As a point of comparison I tried this same test with a few other electric random orbitals, and it generally took them 20-50% longer to complete the task. Then, in the spirit of aggressive test cases, I jumped directly from 80 grit to 400 on the DEROS, and within another couple minutes of going at it, the board looked and felt like a piece of highly polished glass. To be clear, I’m not suggesting that this is good woodworking practice, but the power of this sander allows it to deliver great performance, even with finer abrasives. The surface quality that this machine produces is simply astonishing.

Another task in which the power stands out is in sanding end grain. Even with a good quality AC electric sander this task can be slow and arduous. The muscle of this sander makes the process go much more quickly, while the light weight and ergonomic handling make it much easier and less “jerky”.

The DEROS also runs quietly, especially for a sander with so much power. I compared it to a few other random orbital sanders that I have in my shop and found that the DEROS ran 3-5 decibels quieter, even with the dust extraction running. If I take that a step further and assume that I will be running my dust collector with the other sanders (which is normally the case) and I won’t need this with the Mirka, then the Mirka runs about 8-10 decibels quieter, which is a substantial difference.

Dust extraction

One of the key benefits of the overall DEROS system resides in its ability to extract nearly all perceptible dust directly at the source during normal sanding operations. This does not just include sanding a horizontal flat surface; I also found the extraction to be effective on vertical and inverted surfaces, as well as edges and end grain. The dust collection effectiveness is the result of three aspects of the system:

• The DEROS sander itself incorporates good airflow with an enlarged central dust port that delivers strong suction all the way through the pad.

• The powerful, quiet extraction system delivers great air flow to the tool, with an auto-start feature that turns the extractor on and off as the sander’s switch is engaged. The extractor also features a neat mechanism to clean the filter without opening the housing, which is convenient and really helps to maintain strong air flow. With conventional shop vacuums this process is messy, by frequently opening the vacuum to clean the filter a ton of dust can be launched into the air, much of the benefit of using a vacuum is lost.

I also like the quick disconnect feature that is located a short distance away from the tool. Many sanders locate this right at the tool itself, and by moving it away from the work surface, Mirka has made the work area less cumbersome.

• The Mirka Abranet abrasives also play an important role in delivering optimal dust collection. Constructed of a mesh material similar to abrasives used by drywall tapers, these abrasive sheets allow dust to flow more freely through to the collection system. They also proved to be quite durable, maintaining their abrasive quality for a noticeably longer period than typical sanding disks that I have used (Mirka claims that these disks last from 2-5 times longer than standard abrasive disks depending on the application). I also tested the DEROS with some standard abrasives and found that the system performed well, but left a bit more dust behind than the Abranet disks. This system also comes with a thin foam pad that is installed between the sander’s sanding pad and the Abranet disk, called a “pad protector”. I believe that this device should always be used with the Abranet disks because the mesh quality of the disk allows more wear to occur on the pad’s hook and loop system. I will expect to swap the pad protector on a periodic basis, but this is as quick and simple as replacing a sanding disk, and costs less than $10.

Surely there has to be a downside…

Plastic trigger.

Call me old fashioned, but for a sander in this price range, I want a metal trigger. It works fine, and I have no reason to doubt Mirka’s claim that they have never heard of one breaking, but it feels like an Achilles’ heel in an otherwise bullet-proof sander.

Requires dust extraction system.

I’m uber impressed with the dust extraction capabilities that this sanding system provides. But, it’s that or nothing. There are occasions when I want to use a sander without the full dust extraction setup, and for those situations I’d like to have a bag or similar built-in dust capture system.

Conclusions

This sander is the bomb! Its combination of power, ergonomics, and world-class dust collection put it into its own league relative to the field of electric random orbital sanders. This sander commands a high price tag, but I believe it is well worth it for woodworkers who demand extreme quality and performance.

Source

• Mirka Abrasives, Inc.
• 7950 Bavaria Road
• Twinsburg, Ohio 44087
• Tel. 330-963-6421
• mirka-usa.com
• mirkaderos.com (specific microsite for DEROS sander)


• Sander can be purchased separately:
• Mirka DEROS MID55020CAUS, 5” Mirka DEROS Electric Sander, $595


• Or available as part of a kit:
• Mirka MID550-912-5 – 5″ DEROS Dust-Free System Kit with 5.5m (18′) Hose, $1,347


• Abranet Abrasives
• Mirka 9A-232-120 5-Inch 120 Grit Mesh Abrasive Dust Free Sanding Discs, Box of 50 Disks, $35 (other grits available as well)