Talking Tools: Sander Types & Uses

    Sanding isn't something that most people enjoy. However, whether you're a major DIY-er, or doing the one-off-painting, building or woodworking project, chances are you're going to do some sanding at some point. As an enthusiastic wood worker, and DIY repairman around my home, I can say that I've put several sanders through their paces and I've used them on everything from sanding your average selection of wooden furniture, parts of a house like doors, windows, gyprock walls, wood paneling, then moved onto outdoor projects like bicycles, rocks, and even ironbark sleepers for garden beds.

    Before we get to sanders.... let's talk about sandpaper:

    "Sanding" has been traced back to the 13th century in China. Only, they really did use sand and rubbed it over their work surface. There seems to be some dispute about whether or not it was glued to any sort of backing, but it was an effective (albeit crude by today's standards) method that smoothed surfaces very well.

    Sand in varying grades, was used for centuries, (and still used in sand blasting operations) and eventually glued to some sort of backing fabric. However, the sand particles weren't always evenly sized, and the grains themselves wore down into smooth, less abrasive shapes, so they eventually became ineffective and needed replacement.

    In the 20th century, natural minerals such as garnet, and man made materials such as Aluminium Oxides became useful. Not only because they were considerably harder (and thus longer lasting), but also because they could be crushed and sifted to even sized particles. Materials such as emery and waterproof papers, with better adhesives made sanding paper better than ever before.

    Now with various types of sandpaper available, please realise that there is no "one size fits all" solution. Sand papers are used in a variety of different settings and purposes. Ranging from removing rust and old paint from surfaces with really rough, gritty paper... all they way up to polishing glass, metal, and glossy surfaces with an ultra-fine grit.

    Sanding is a trade off between speed and result... or perhaps how aggressively material is removed versus the quality of the finish. If you use a really aggressive, rough sandpaper, you can expect it to remove material very quickly, but the finish will feel rough to the touch. If you use this approach on the wrong material, you may permanently scratch, or even sand dents into your work piece. So you have to keep that sander moving to avoid that situation. Alternatively, if you use a smoother sandpaper, you can get a really nice smooth finish, but you would be there forever if you had to remove rust and tougher paint jobs.

    It's for this reason, most wood workers start with a coarse sandpaper, and work their way through to smoother and smoother grades of sandpaper until they find the surface satisfactory.

    Let's talk about grit, and the numbers...

    Grit ratings have got many explanations (not all of them informed). Some talk about how many particles successfully fall through a sieve of some kind that has only 1 square inch in area. Frankly, I find those explanations, flawed, and somewhat useless.

    You'll see sandpaper grit ratings printed on the back of the sheet. Numbers will range from 20 to 8000. Frankly, I don't care how many particles are in a square inch... I only care how well it sands for my purposes. So let's get this clear in four points.

     

    1. The lower the number, the coarser/rougher the paper. You'll have a lower number of "abrasive grains" in any given area, but those grains will be huge, sticking out a long way from the sheet. Such coarse sand papers (whether or not they actually use sand, garnet, aluminium oxides, or something even harder) will both sand very quickly, but also tear surfaces asunder, and leave deep scratches in the surface. Coarse ratings (for wood working) is anything below 80 grit. Use this whenever material removal is your goal, (rust, old paint or varnish for example), and you're planning to smooth it over with a finer sanding paper later.
    2. The higher the number, the finer/smoother the paper. You'll have a higher number of "abrasive grains" all packed together in a given area, but the grains will become progressively smaller. This means that they will be less and less likely to scratch your surface, but they will take longer and longer to achieve a good result. For wood working, I rarely go above 400 grit (especially with a powered sander), but metal workers/polishers, and knife makers may go up to 2000, or even 8000 for a really fine polish.
    3. Going beyond the wood itself...Are you looking for a matte finish or a gloss? A matte finish may only need to go up to 180 grit, but the gloss will benefit from 320 and maybe 400. I generally start with 80 grit, then 180, then 320, then maybe 400. If you're looking into going really glossy, then you will be lightly sanding after you put the first coat of varnish down. You might ask: "Wait, why would I remove the varnish I just put on?" because it will remove the "high spots" in your varnishing, allowing a second coat to be more even. By building up your varnish in multiple, thin layers, the varnish dries more completely, and fills in any low spots of the underlying layer, while sanding the successive layers (still lightly, with a fine grit paper) will give the next coat a more even surface, which will really bring out that shiny final third, or even fourth coat. If you do this, it's best to sand by hand between coats, with a grit of at least 320.
    4. Keep some really fine sandpaper around, 800, 1000, even 2000. It's great for removing light rust from the metal surfaces of tools without grinding your metal away.

    Introduction into the various types of hand held sanders:

    Now if you're new to sanding, you may be confused about which sander to get. Ignoring the multitude of bench or stand-mounted woodworking sanders, for now I'm going to limit it to the hand held power tool sander types that beginners might buy when they walk into a hardware store. So let's start with the most aggressive and work our way down to the finer styles of sander.

    1. The Belt Sander:

    This sander uses thick sheets of sand paper, with the ends glued together to form a ring or belt. The belt width and circumference should match your sander's specification or it won't work. Belt sanders have a bit of a mixed reputation, because their ability to remove a LOT of material (especially with coarse sandpapers like 40, 60, or 80 grit) is both the point of a belt sander, and the biggest issue when you make a mistake like not keeping it level, or letting the sander sit in one space for too long.

    A general guide is:

    • Keep the sander flat to the sanding surface! This is the thing most people slip up on.
    • Keep it moving or you'll have a dug a hole in the wood within seconds, particularly on softer woods.
    • It's entirely ok to scribble a pencil line all over your surface, sand the surface evenly until the line has disappeared, then feel free to mark it again with the pencil and sand evenly again. This helps to show which bits you've sanded, and what needs work, it also helps to keep the surface even.

    The belt sander is more for covering large areas of flat surfaces (like doors, table tops, and maybe even floors if you don't have a floor sander). As long as you keep the sander pointing vaguely with the wood grain, (some people use a diagonal, cross hatching motion) and move at a reasonable pace consistently, the results can be fantastic. However, for a handheld tool, belt sanders can be very heavy, and wide enough to make it hard to balance on thin edges of planks of wood. For this reason it's generally advisable to clamp some scrap on either side of your narrower wood or edge-faced pieces to provide support against tilting.

    What is a belt sander good for?

    Belt sanders are great for open flat surfaces, but they really struggle to get into corners, inside edges and tight spaces. So it's generally best if you sand the pieces from edge to edge before you assemble your project. Because belt sanders are the heaviest hand-held type, they rapidly tire your arms if you're working on vertical or upside down surfaces like ceilings. Or you could think of it as a great workout.. up to you. For big strong guys, a belt sander is a powerful tool to have, and also incredibly versatile if you flip it over, and use like a bench mounted linear finisher (called a "linisher") for sanding, sharpening, and grinding purposes. However, because it is so aggressive and the least forgiving type of hand held sander, it's not what I'd recommend for a first sander. But don't let me scare you off!

    While it's easy to learn the technique necessary to use a belt sander well, many people don't bother before they get themselves into trouble. To save you from that problem, I've included this video "how to".

     

    A few words of warning: These sanders have two issues that need considering.

    1.  Belt sanders can run away because they operate much like the tracks on your average army tank, if you use the trigger lock (to keep the sander on without you holding the trigger in constantly) and you lose power (blackout, unplugging, circuit tripping are just a few of the usual examples) it's likely you'll put the sander down to investigate the problem. Then when you're away and the power comes back on, the sander may suddenly scream across your floor/table/whatever and crash quite spectacularly. The bigger models can hit with sufficient force to hurt pets, ankles, and damage whatever they run into (and themselves).
    2. Efficient (or aggressive) sanding means a lot of dust: You should always wear a dust mask of some variety when sanding. Bigger and faster belt sanders can eject a constant visible stream of dust though the ejection port. If you aren't using a bag, (and emptying it regularly) the dust can go everywhere. I'm not kidding. My sander's dust port is a bit of a weird shape, so adapting to a shop vac or dust extractor required some creativity. Don't let a challenge keep you from making your workplace safer, cleaner, and more enjoyable to be in.

    2. Disk, Orbital and Random Orbital Sanders (ROS):

    Basically seen as a middle-of-the-road types of sander. Less aggressive than belt sanders, disk and orbital sanders usually have flat circular disks (between 100mm-and 150mm in diameter, attached by glue or velcro, which spin in circles and/or orbits). While cheaper, the down side of a pure disk/orbital sanders is that they leave circular swirl marks on the sanded wooden surface. Random orbit sanders (or "R.O.S.") move in a more complicated manner and they don't leave the swirl marks, leaving a better and smoother finish. Naturally random orbital sander are more expensive, but have become cheaper over time and now dominate the market. I own a random orbital sander, and if I had to choose just one type, I'd buy a random orbital sander. Also, please note, that a larger disk size can speed up your work significantly. There's a 43.4% increase in area between a 125mm and 150mm disk, think how much time can be saved on larger projects if you were 43.4% faster! Smaller models do have a place though, especially in tighter spaces, and do suit people on tighter budgets.

    What is a random orbit sander good for?

    Random orbit sanders are the "all rounder" option. They can be used on large surfaces like a belt sander, but are able to get closer (but not all the way) into edges and corners. They are a less aggressive sander, compared to belt models, but remember that any sander can dig holes when used improperly... it's just a little less likely than a belt sander. Random Orbit Sanders have a unique versatility when the backing pads come in varying sizes and hardnesses. Harder pads are great for flattening surfaces, while softer ones are better on curved surfaces like spheres. Using a bigger pad means surfaces get done faster and more evenly, while smaller pads make the sander more manoeuvrable, lighter, smaller and more able to reach further inside corners and edges.

    Again, because of the pads orbital and vibrating motion, random orbital sanders will vibrate and kick when pressed into a corner or edge, so reaching right into the corners will never really be an option. However, some sanders have smaller vibration distances of 3mm and others have 5mm. The 3mm gets closer into corners than the 5mm model, but the 5mm model will work faster on open surfaces than the 3mm. In either case, you're still better off if you sand the pieces with any ROS before assembly for a consistent finish.

    Being lighter than belt sanders, vertical and upside down sanding becomes more manageable, but still quite hard on the arms over time. Bigger sanders can have smaller pads, but smaller sanders really aren't built to handle the extra friction and corresponding motor load caused by using bigger pads. So if you're routinely worried about the weight when working on walls or ceilings, you might want to consider a 100mm or a 125mm ROS over a 150mm model.

    While the sheer torrent of dust is less than a belt sander, a dust mask and/or dust extraction, combined with eye protection of some type is, in my opinion essential, particularly when the sander is above your head, and dropping all kinds of junk into your face.

    Random orbit sanders can take you all the way from a crude, very rough surface to a fine finish and do so within a reasonable time. So they really are a "Jack of all trades" sander. I'd also recommend this to beginners because you can work with a reduced risk of digging holes into your wood like the belt sander. However, as discussed, they really struggle to reach into those crevices, and still can be very heavy if you don't get one that suits you.

    Here's a video on how to use an ROS:

     

    A note about this video: George Vondriska is almost a wood working celebrity online. He's done online video classes for the Woodworkers Guild of America, The Great Courses, and has videos all over YouTube. He even runs his own classes in Wisconsin, U.S.A. He is perhaps one of the best presenters, his videos are professionally done, to the point, and clearly demonstrate that he has decades of experience.

    Why did I add this video? I really love Steve Ramsay's channel, he really knows his stuff, and despite his shamelessly badly-acted-yet-somehow-still-entertaining adverts for the MicroJig, some mattress company, and whoever else will sponsor him. He's down-to-earth, brutally honest about his quirks, and has a sense of humour I appreciate.  Steve's "basic toolbox for under $1000 (USD)" is a good starting guide. I just think some people would rather pick and mix rather than shelling it all out at once. So that's why I have done my own version found here at: WaywardHam's Toolbox Ideas.

    For those nooks and cranny's I've been complaining about, it's time I got to the smallest sanders, the finishing sander, and the oscillating tool.

    3. The Finishing Sander:


    Finishing sanders are typically the smallest dedicated powered sander, and they're fantastic in creating smoother surfaces (and can go up to 240 grit paper), are ideally suited for smaller projects and for use in some of the harder-to-reach places. Being lighter than most, it makes work on vertical surfaces MUCH easier. However, because they're slower sanders, you'll be holding that sander up for a longer period of time. So there's a trade-off there. I mostly use this one to make or restore chopping boards, picture frames, and final sanding tasks on timber furniture. However, I should note that this is probably the sander I'd recommend for children and elderly folks when weight and skill can be an issue.

    Finishing sanders, by definition, are designed to create smooth finishes, and are used at the end once the heavy sanding has been done. You could sand a large scale or very rough surface with it, but you'd be there for a long time. I started with this type of sander, and as a beginner sander, taking very little off the work piece, it's very forgiving. However, once I started working on much larger projects, my next purchase skipped the ROS, and went straight to a belt sander because my next job was massive. As you might imagine, there was quite a difference there. So while I do recommend a finishing sander for it's intended purpose and beginners, please remember that it's certainly not suited to everything. Finishing sanders tend to have hard, flat plates, so they're not very good for concave or convex surfaces. Similarly, because they vibrate, getting into the corners is still a difficult prospect, but you can get very close, more so than ROSs and belt sanders at least!

    If at all possible, I would suggest that you attach some sort vacuum or dust extraction to a finishing sander as the dust is particularly fine, which means it's airborne for a long time and is the most hazardous type for your health. A good dust mask is also highly recommended. The dust bag that comes with models like this works as advertised, but that isn't the best solution and can fill up pretty quickly because the small sander comes with a small bag. The added suction of a dust extractor/or shop vac makes a significant difference in sanding speeds too as the paper takes longer to clog up.

    Finishing sanders can come in a variety of shapes. Some look like smaller ROS's with circular pads, some have square or rectangular bases, but mine has a base that looks like a clothes iron. (It's used to remove the wrinkles in wood after all) A squarish back with a pointed front works quite well in both sanding flat surfaces, as well as the hard to reach corners inside boxes, frames, and between slatted/spindled components of furniture. However, the lack of a soft base means it's not ideal for curved surfaces. For concave surfaces, that's a whole different ball game, and even the finishing sander won't get into tighter curves.

    Remember, on clothes iron-shaped finishing sanders, you have to buy the triangular paper for the front, AND the rectangular paper for the back separately. (You need one of each to cover the entire sanding base of the sander) That means you need two packets of sanding sheets for EVERY grade of paper. Which can be a bit of a bother, but that also means you can have two different grades if you'd like. I generally like to have the same front and back, but it has been handy to have a finer and a coarser paper on at the same time for certain occasions. For circular, square or rectangular finishing sanders, you can probably just buy the one sheet for the whole surface.

    Here's a how-to video on finishing sanders:

     

     4. Oscillating tools with sanding head:

    This is a relatively new, safe, and easy-to-use offering in the tool world. While it's not a dedicated sanding tool, (since it can do a lot of things, depending on the attachments being used) it's often referred to as a "detail sander". The sanding heads are usually shaped like small equilateral triangles where each side might bow outward a bit, and sides can range from 40-90mm long. On some models, the pads are your typical hard plastic, while others have a soft, sponge-like backing. By combining very small oscillation distances, and small triangular heads, and the option of a soft pad, reaching into corners, and even some concave surfaces is pretty easy and forgiving.

    Naturally, being so small, you do not want to be using this device to do heavy duty, and massive projects, but the size makes this type of sander a kid/elderly friendly tool because it is quite light. The oscillation, even when a blade is attached, moves back and forth over a 0.5-4mm, what this means is instead of cutting skin, it merely "jiggles" it around your bones. I've brushed up against both metal and wood cutting blades on mine when running, and I didn't even get a scratch. So this too; poses little threat to bodily harm of skin-covered areas (finger nails... not so safe). But given the option to connect blades and other accessories to this type of tool, I'd discourage this option for younger children because of the damage they can do to non-living things like furniture, walls, floors, pipes, electrical cables, your neighbour's letterbox, your mother-in-law's car, your new 85" OLED tv, larger appliances, etc, which I can assure you, the tool will cut.

    Have a look at this video for a demonstration, I've skipped some so it goes straight to the sanding part:

     

    So a detail sander/oscillating tool with sander head is good for (when sanding):
     
    Nooks, crannies, vertical surfaces, ceilings, smaller to medium sized projects, getting between spaced slats, boards, and any lighter duty tasks. However, most oscillating tools do not have a dust port. This means you're better off doing this sort of sanding outside, on a drop sheet, or on some sort of easily vacuumed surface. Dust masks, eye protection, and hearing protection is perhaps most critical with this type of sander.

    Why haven't I done all the workshop (stationary machinery type) sanders, like oscillating spindles, bench sanders, disk sanders, linishers, drum sanders, etc?

    In short, that's a topic for people who are getting more serious in their hobby, and beyond the scope of this particular article. Sure, they're handy, but they can go up to thousands of dollars, depending on the size, power, and quality of the tool. I think I've written enough here.

    Stay safe and have fun!

    Ham.


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