Bosch GSS20-40 Review

A compact, light weight sander with vigorous sanding action and minimal vibration.

Bosch GSS20-40

Bosch 1/4-Sheet Orbital Finishing Sander

There are three distinct advantages to quarter sheet sanders – the shape of the base enables them to sand close to inside corners, their small size makes them easy to control, and they can be typically had for well under $100. Apart for sanding into corners and flush up against sides, they're handy for working on narrow stock such as table legs, aprons, and drawer parts.

Key features that you want to consider when shopping for one of these sanders is motor power, the paper clamping mechanism, dust collection, and vibration level.

I've been using Bosch sanders for quite some time – one of my favourite random orbital sanders continues to be the Bosch ROS65VC that I've been using over the past five years – so I was looking forward to reviewing their quarter sheet sander, the GSS20-40.



The 2.0-amp motor on the GSS20-40 is a typical size for a quarter sheet sander. It produces a constant 12,000 oscillations per minute (OPM) and is located inline with the soft-grip handle and sanding pad. This makes for an extremely well-balanced tool with all the weight located right under your hand. In use, you barely need to apply any downward pressure when sanding – just let the sander do the work. 

I find the sander speed ample enough to deliver a super smooth surface reasonably quickly. Variable speed would have been a nice addition to this sander, for example when sanding inlays, either parquetry or marquetry. However, if like me, the amount of inlaying you do is fairly limited, then variable speed won't likely be an issue. And, the addition of variable speed would likely move the sander to a higher price point.

With the soft-grip handle directly over the motor the sander is very comfortable to use with one hand and has very good balance. Controlling the direction of movement is very easy.

I like the rocker style, dust-sealed power switch located just at the front of the handle – you can quickly manipulate it with your forefinger. There's also a decent 7-1/2 foot power cord – and when it comes to cords, longer is better.



As with most quarter sheet sanders, the GSS20-40 has a pair of wire clamps for tool-less paper change. The wires are thick enough that they're highly unlikely to bend out of shape over time. The loops on the end are large enough to lift with a fingertip.


I find the clamp levers easy to operate and they hold the sandpaper securely. You can install a new sheet of paper in 10-15 seconds. All you need to do is rip a standard 9 by 11 sheet of plain backed sandpaper into 4 pieces. Bosch says that you can use PSA paper, but I'd avoid doing so – the paper is more expensive, and is more time consuming to remove.


The GSS20-40 comes with a paper punch – a plastic plate with 6 raised nibs. After the paper is mounted onto the sander you simply press the sander down onto the punch plate. There are two holes pre-drilled in the middle of the plate should you want to mount it on a base or on the wall.


The paper punch makes holes that are about 3/16" to 1/4" inch in size. I find if you giggle the punch a bit before removing the sander it does a better job of opening up the holes. Even though there are only 6 holes, I find that the sander does a pretty good job of collecting dust. 


All sanders produce very fine dust, and no matter how diligent you are, enough of it will get into the air such that you'll want to wear a dust mask, or better yet, a respirator. If you're looking for a light weight respirator that's comfortable to wear and very effective, then check out the Elipse.

The GSS20-40 is equipped with an efficient microfilter dust canister that contains a removable paper micro filter that traps particles as small as .5 micron. The filter has a screw-off cap that makes it very easy to empty the canister, which is something I do after every sanding session. Gently tapping the micro filter against the soft edge of a waste container dislodges most of the dust. Occasionally I'll blow it clean with compressed air.

The cannister attaches to a 1-1/8" I.D. port on the sander. You'll get even better dust management if you've a suitable diameter hose to connect the sander to a dust extractor.



All power tools vibrate – some more than others. According to the folks at Bosch, the counterbalancing of the drive shaft is the main element in minimizing vibration on the GSS20-40. Sure enough works, as in use I find the sander produces very little vibration. The sound level was in line with the other sanders I use – an average of 76 decibels at 3' from the sander.

The Bosch GSS20-40 is, in my view, a good choice in a quarter sheet sander for fine sanding – corners, edges, narrow stock, and for refinishing projects. It creates a vigorous sanding action and transmits only a small amount of vibration to your hand and forearm, so that you can use it for extended periods of time without discomfort. It's compact, and at under three pounds, none too heavy. 


  • Power: 2.0-amp motor
  • Power Cord: 8 feet
  • No Load Speed: 12,000 OPM
  • Sound Level: 76 decibels (at 6 feet)
  • Pad Size: 4" x 4-1/2"
  • Paper Clamping Mechanism: Standard Metal Clips
  • Weight: 2.7 pounds
  • Power Cord: 7-1/2'
  • Dust Collection: Microfilter Canister
  • Warranty: 1 year
  • Includes: Punch plate, 1 sheet sandpaper, Microfilter Dust Canister

MADE IN:Switzerland

Carl Duguay
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