Canadian Woodworking

Random Orbit Sanders


If you've never tried a random orbit sander (ROS) before, you'll be amazed. It is the one sander I use most in my workshop for finish sanding.

In fact, with the proper technique, a random orbit sander gives you finish-quality results without any hand sanding at all. If you prefer, finish up with some 220 grit hand sanding after taking your random orbit sander through its paces, one grit level at a time.

Most random orbit sanders have either 5″ or 6″ sanding pads, although some models have 4½” pads. Five inch pads are the most common. A 6″ sander will cover more ground in a shorter period of time, though it is a more expensive option. Larger sanders weigh more and hang over the edges of smaller parts, inadvertently putting a small curve on these parts. If you have smaller hands, then a more compact sander will be easier to handle.

You’ll find brands with five or eight holes in the sanding pad, so you’ll have to find the sandpaper to match. I’m not sure that it makes much difference whether you go with five holes or eight, but I suppose that more holes will collect sawdust off your project more efficiently.

Random orbit sanders come with a dust collection port. Some have a cloth bag attachment, while others use a porous plastic-like canister. I find the canister type easier to empty, but either work fine. Some sanders have a round port so that you can attach a vacuum hose instead of the provided canister. If you use a vacuum hose, be extra careful, as it is important to keep your sander flat and running smoothly to avoid any gouges or uneven areas. The hose can also damage delicate corners of your project. Alternatively, use a good dust mask, crank up your ambient air cleaner, and/or consider a down-draft sanding table.

Random orbit sanders have two different sanding pad styles. One is a flat pad that accepts adhesive-backed sandpaper. The other is called a ‘hook-and-loop’ pad, which allows hook and loop sandpaper disks to stick on without any adhesive.

The industry has turned towards hook and loop pads in a big way, and with good reason. Adhesive backed disks are hard to reuse because if there is a little bit of sawdust on the back it won’t adhere well. I often use a sanding disk for just a few minutes, and then need to move up to the next higher grit level. The first disk is far from being used up. Because it has a hook and loop back, I can remove it from the sander and reapply it numerous times, making efficient use of my sanding disks.

If you have an older model that only accepts adhesive backed disks, ask the manufacturer whether they offer a replacement hook and loop pad. If not, some woodworking outlets sell a conversion disk that has a PSA (Pressure Sensitive Adhesive) back to connect to the sander, but a hook and loop surface on the other side. Once you try the hook and loop method, you’ll never go back.

You’ll find both fixed and variable speed models on the market, with a slightly higher price for the latter. A fixed speed model generally runs at around 12,000 opm (oscillations per minute). Variable speed models generally run from about 5,000 or 7,000 opm, up to about 12,000 opm.

I own a variable speed model because I purchased it on sale for about the same price as a fixed speed model. I almost never use it below its top speed. The faster it runs, the more quickly it does its work. I do appreciate the slower speed, though, when I use my random orbit sander as a buffing machine. For this, place a soft cloth or towel directly under the sanding pad (without sandpaper), and the sander becomes a great machine for buffing out a coat of wax after final finishing. I’ve also heard that people using random orbit sanders for auto body work prefer to use slower speeds on metal.

Don’t think that the slower speeds will allow you to use a random orbit sander between finish coats. I find the machine too aggressive for that task, preferring to use hand sanding methods. Still, if you can buy a variable speed model for just a small fraction more than fixed speed, it would be well worth it. I definitely don’t consider the variable speed to be a necessity though, as I do with my routers.

One of the dangers of a random orbit sander is turning it on before placing the machine on your workpiece, or coming off the workpiece with the sander still running at top speed. Unlike an orbit pad sander, like a ¼ or ⅓ sheet sander, random orbit sanders are just not designed to run when off the wood. I always turn the sander on when it is already on the wood. I also turn it off while still in contact with the surface, always moving until the sander slows down to an obvious rumble. I pull the sander off when it gets to this slower speed.

Manufacturers have tried to limit the damage done by random orbit sanders during these on-the-surface and off-the- surface moments, with a pad brake or pad control system. Essentially, it’s a system that limits the top speed the sander can reach when not in contact with the wood.

Unfortunately, I still find that the higher speed reached when not held back by surface friction is just too risky for any fine work. If the random orbit sander you’re thinking of buying has some sort of speed control system, then it sure doesn’t hurt. But use the method I described above when starting and stopping your sander, and you’ll never have a problem.

Something you may overlook is the comfort of the tool. Random orbit sanders are used for long stretches of time. Sometimes, one of my sanding sessions can literally last an entire day or more, especially where the project involves a large number of case goods such as bookcases or other cabinets. So comfort shouldn’t be underrated.

If you have particularly small hands, you should find a model that isn’t too large, allowing your hand to fit around the tool without excessive reaching or cramping.

Cord length is another often overlooked feature. It can be frustrating to have a power tool with a cord so short that you need an extension cord every time you use it. If you can find a model with a longer cord, then you will have more flexibility to move freely around your workshop.

It is easy to undervalue the benefit of good sanding. Yet many staining and finishing disasters can be traced back to incorrect surface preparation. Do yourself a favour and try to develop a little more patience. Patience gets you through the sanding tasks with your sanity intact, and a much better finishing result to show for it.

Palm sanders are best for single handed use and are ideal for finish sanding. Pistol or “D” grip sanders, in general, tend to be a bit heavier and have a longer orbital stroke for more aggressive sanding. When sanding for long periods of time many people find the larger handles (which you can use two handed) more comfortable. Barrel grip or grinder style random orbit sanders are the real workhorses when it comes to random orbit sanding. They are among the heaviest and most aggressive ROS’s. All the models we’ve seen connect directly to a shop vac, and can be used for a variety of polishing jobs as well.

The Fein MSF636 is a good example of this style. It has a 380 watt motor operating at 7500 opm, with a large 5⁄16″ orbit. It features an 8-hole H&L pad, a 1¼” vac adapter and weighs in at 1.7 kg (3.7 lbs). It comes with a 3 year warranty and is priced at $680.

Note: Prices listed in this review were correct at time of printing, but may not reflect current prices. See links/retailer for updated prices.

5″ Palm Grip
Ryobi RS281
Ridgid R2600
Milwaukee 6019-6
Makita B05012K
Bosch 1295DVSK
DeWalt D26453
Porter Cable 333VSK


5″ Pistol Grip
Bosch 3725DEVS
Hitachi SV13YA
Metabo SXE450
Makita B05021K


6″ Pistol Grip
Bosch 3727DVES
Makita B06030
Ridgid R2611

Last modified: June 5, 2024

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