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Everybody hates sanding, but a professional looking project depends on it. After watching the video above and reading this article you’ll be turning out beautifully smooth and tasteful projects, in no time.
Like many things in woodworking there are different tools for different sanding techniques. I won’t cover every single one here, but we’ll talk about the most common.
I always finish up with a bit of hand sanding on my projects, whether it’s to break the sharp edges or get into a tight spot. If I’m looking to keep the surface flat, I’ll use a sanding block.
Sanding blocks come in many different forms and can be as easy as wrapping a piece of sandpaper around a scrap piece of wood. I’ve had this molded rubber block for a couple of decades and it works great for flat sanding.
There is also a disposable product out there that is a foam pad covered with abrasive. They aren’t my favorite thing to use, but they have their place.
An orbital sheet sander is an electric tool that spins in a very tight orbital motion. It’s such a tight, consistent motion that the sheet sander leaves straight tracks behind it. For this reason, it should be used in the direction of the grain. Sanding across the grain with a sheet sander tears up the wood in a way that can only be fixed by spending quite a while sanding with the grain.
The sheet sander pictured above is a palm sander since it is used one handed and doesn’t have a pistol grip. It has a square pad with several holes in it for dust collection. The fan inside creates a vacuum to suck the dust up into the channels and to the bag – as long as the sandpaper also has holes in it.
The sheet sander uses 1/4 sized sandpaper – 1/4 of a 9”x11” sheet. You can also buy sheets with holes that are already sized and meant for a sheet sander, but I’ve never wasted money on these. I just cut down a larger sheet and slap it on! The sandpaper is held down with a wire latch in the front and back.
The pad is square, so it fits into corners nicely, but, overall, the sheet sander just isn’t very aggressive. For this reason it’s really only good for finishing tasks. When I use it, it’s to sand right before the last coat of finish and it’s great for that.
The random orbit sander is probably the most popular sander today. It’s similar to the sheet sander in that it has a pad with holes for dust collection and it’s also a palm sander. It both spins and oscillates, so it creates a varying pattern that doesn’t leave distinct scratches. Because of the varying pattern the random orbit sander can be used in any direction – with or against the grain – and this is mainly what makes it so popular.
The random orbit sander uses round sheets of sandpaper that are made for it and these discs have holes cut to match the holes in the pad. It has the ability to be quite aggressive with some lower grit sandpaper (we’ll discuss more on that later) or go for a lighter touch with higher grit.
You can also remove the bag and connect a wet/dry vac to the port. This results in much stronger suction and better dust collection, but it’s a little less convenient. I usually hook up the wet/dry vac if I’m in for a significant amount of sanding.
I won’t talk much about the belt sander, but it is worth a mention. It can pretty much sand to depth of your project’s soul. It also has a very distinct sanding pattern and shouldn’t be used across the grain. I only use mine in situations where I screw up. In the case of the round table I built a few months ago, I used terribly wet and unstable wood and had to go to town on it with a belt sander because it moved so much after assembly. If you use dry wood and cut your joinery even semi-accurately, you won’t need a belt sander.
There is also a category of bench top sanders. These sanders are straight-forward examples of the handheld tools, but mounted to a table/bench. They also have tables of their own that can be set to 90 degrees for a perfectly square sanding or tilted to make bevels.
Sandpaper is covered in abrasives that can either be synthetic or mineral and then resin is poured over them to lock everything in. The number you see on the package – or on the back of the sandpaper – is called the grit. The grit refers to the size of the abrasives on the paper. The bigger the number (higher the grit) the smaller the abrasive.
It not only comes in sizes and shapes specifically for different tools (FIG 7), but also in larger sheets (FIG 8). Those sheets can be cut down to fit various sanders or folded to be used by hand. My favorite use for full sheets is with CA glue and masking tape.
An aggressive grit is considered below 100. 100 to 220 is a medium grit, and 220 + is fine grit.
How to Sand and Get Great Results
Start by looking at your project and determining what it is that you need to accomplish. There are times when a significant amount of sanding needs to be done to remove defects or paint, etc….and then there are times when you only need to lightly sand with one grit and call it a day. Whatever the case may be, this will determine the grit you start with.
Since an aggressive sandpaper such as 60 grit cuts much deeper than 220 grit, you’ll need to use incrementally larger grits to gradually remove and replace those cuts with smaller ones. Trying to remove the scratches from a 60 grit sandpaper with a 220 grit will take an eternity.
It’s much more time and resource efficient to go from 60 grit to 80 or 100 grit….then another step to 150 or 180…and finish with 220. I never use higher than 220 grit, anymore. Higher grits lay the wood fibers over and make it hard for your stain/finish/et al, to soak in.
The idea is to think of sanding an entire surface, at a time, and not specific spots. A good way to help visual your progress is to mark the surface with a pencil. Once the pencil is not visible in an area you are done in that area and should move on.
One thing I do right before sanding with 220 grit is wet the surface down with water. Water excites the wood fibers, and raises them, so you can sand them down before applying finish. If you don’t, they will raise during the finish application and you won’t be able deal with them as thoroughly. So, spray water on a clean rag and wipe the surfaces down really well.
The most common mistake made when sanding is putting too much pressure on the sander, it’s a joke, by the way). An electric sander will do the work, you just need to guide it. The harder you push the slower it spins and oscillates and the less wood it will remove.
FIG 11 is a shot of a demonstration I did in the video. It shows how the random orbit sander (far right) left no scratches or pattern, the sheet sander (middle) left distinct, straight tracks, and the belt sander, likewise, left distinct tracks. This was done across the grain and it shows that the random orbit sander is the only one that does an acceptable job.
The last tip I’ve got is for sanding plywood. Plywood is made of several thin sheets of wood glued together in alternating grain patterns. So, you can lightly sand plywood, but, if you go too far, you’ll burn through the top layer.
As woodworking goes sanding is pretty safe. The biggest consideration is to always wear a respirator. Dust masks aren’t good enough since they don’t form an airtight seal. Always wear a respirator or something like an RZ mask that seals over your nose and mouth.
The electric sanders have vents, so the fan spinning inside can move air. Be careful not to get your finger in there too far. The vents are generally pretty deep, but keep that in mind.
Lastly, let the sander come to a complete stop before touching it. Sanding your hand really burns!
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