Sanding, I loathe doing it, but it is a necessary evil. For finer work and the ultimate finish, hand sanding can be far more tactile than any machine or tool. Even the hint of a hand-sanded arris edge can be enough to raise a piece, and trying to achieve the same consistency with a mechanical sander can be all but impossible, but machines have eased the majority of sanding tasks.
Of course abrasives play a very important part in the finish, but here I’m concentrating on the different types of sanding machines, what they do, and which specific ones you need Sanding is often seen as the last task prior to applying a finish, but good practice is to clean up what will become inaccessible areas prior to assembly, such as internal faces and edges, and backs of units; it is far easier to sand a single component that to try and achieve a uniform surface on an assembled one. However, there are times when a piece needs reviving, either with a new coat of finish, or stripping back and starting again, so that very sensible rule goes out the window and more specialised sanders come into their own.
Sanding need not be all about attaining a premium finish either Shaping work for a different look can be easier with a sander and here static bench machines prove useful.
External curvature is easiest when done on a flat surface so a disc sander or a combination belt and disc sander can prove very worthwhile additions, but not only for curves. If the fence and surface table is good, the disc is especially useful for tweaking the fit on mitres or other butting surfaces and as such can be ideal for segmented-style work, either in turning applications or suchlike or achieving crisp clean finishes on end-grain.
The main problem here can be twofold. Firstly, the size of disc on budget models starts at 150mm (6tn) diameter, and as, for safety reasons, you should only use the downside of the disc’s rotation, the sanding area is very limited.
A more useful option is a bigger disc profile, bought as a standalone model.
As the quality of components gets better, so the cheaper aluminium table and rudimentary plastic mitre fence is often replaced by cast-iron tables and a better quality fence, plus the support for the fence tends to be more substantial, eliminating the flex that can occur with lightweight cheaper models.
Be aware that sanding on a fast-running disc can quickly eat away at the workpiece even with a fine grit, plus, if it becomes clogged or the grit dulls, the work can easily start to burn.
There’s no need for excessive force, the lighter touch should do the job — power tool sanders work best under their own steam, not by being leant on.
Machines for curves
Internal curves are often a trickier proposition to clean up, and here a bobbin sander, with its interchangeable sleeve diameters, is ideal.
As with a disc sander, on end-grain or grain transitions from long to end-grain as you get with curves, these work really well, but with the same requirements of care with burning on end-grain, although the oscillating operation assists clean sanding.
Alternatively, if you own a pillar drill, the drum sander is a good substitute, You lose the oscillation function , so there will be a greater likelihood of clogging and burning if the work idles, but this is a cheaper option and ideal if you don’t work curves regularly — and you can still tilt the table for additional scope.
Of course, with disc or bobbin, the action is to sand across the grain when introduced to an edge; sand on long grain and you will be scratching across the grain direction, necessitating a bit more sanding by hand or carefully sanding only from the springing points of the curves.
Internal curves can be worked on the wheel area of the belt if you have a belt and disc sander, or on a handheld belt sander if you invert it or hold it against a fixed piece of work.
Belt sander workhorse
A belt sander will make short work of cleaning back old finish, levelling in irregularities or general flattening, as well as shaping or fairing in curved surfaces but they can be pretty fierce, even when finer grit belts are fitted.
The key is to keep them moving to prevent them wearing ruts in the work, and if you are doing a flattening job on a wide surface, much the same as initial flattening with hand planes, working the sander at a diagonal to the grain and tracking it across the work will give a more uniform flatter surface before moving to running in line with the grain.
The inversion clamps available on some models are handy for static shaping work, much the same as the belt option of a belt and disc machine, but a sanding plate is a better option if you work large flat areas regularly as it will act as a depth stop to prevent the sander from digging in or sanding too deeply in one area.
This is especially so when working with thin veneered surfaces, although given the option, I’d shy away from a belt sander on a finer or more delicate surface. For me, they are much more of a hogging-off machine, predominantiy for large fiat areas before moving on to a finer more controllable sander for the final preparation.
Going into orbit
Back when power sanders first became available, orbital sanders proved popular for finishing work, their rectangular platens accessing corners and recesses when stripping back finishes.
The downside to them, however, is the uniform scratch pattern they leave behind. Firstly, removing a lot of old stock or finish is a slow process even with coarser grits. Secondly, the action is not fine enough to remove those scratch patterns; leap from one grit to another in too big an increment and the deeper scratches won’t be removed properly and will show up when a finish is applied. On a painted surface it’s not so problematic, but on polished or lacquered surfaces the scratch pattern can become more apparent, showing through in tiny circles.
Orbital sanders can give a superb finish though, and the professional models will stay put so you can work them around the component very easily.
The budget market is still an area where these sanders are more popular, but lightweight models may tax the hands with vibration and are not designed for extensive sanding sessions.
Removing stock slowly, orbital sanders are useful for veneer work on sheet materials especially.
Random orbital sanders
For me, the best sander is the random orbital type, although they do require more expensive abrasives. Standard orbital sanders can use pre-cut or roll abrasives, which is usually more economical, although some also take a hook-and-loop Velcro type as well. Random orbital sanders, with their round bases, have to rely on Velcro-backed abrasives oniy, While these sit flat to the base and last longer than the paperbacked sheets that can be used on other sanding options, their expense has to be factored in.
The round base also limits its use in cleaning up old stuff where you have to gain access to internal corners, but even so it’s the best all-round sanding option on the market to my mind.
The random pattern removes stock very quickly, but can be controlled very easily and with the finer grits a premium finish is easily achievable, Options of polishing bonnets and sponges allow waxes to be applied and buffed up to a high gloss finish
Whereas a consistent pattern from an orbital sander can easily be seen, the random orbital leaves a fussy pattern that diffuses the edges and is very difficult to see. When used with finer grits the pattern doesn’t show through a finish as readily.
For me, having the option to remove stock at a steady rate when doing initial clean-ups and also to fine finish within one unit makes it all the more desirable and is my sander of choice, for bigger work especially.
However, for most work I reach for a palm sander These are so easy to manoeuvre, and work well on frames and similar jobs where a bigger machine can be harder to keep on the work.
There are orbital and random orbital versions available, and for some years I opted for a full-sized 150mm-base random orbital for bigger work and a small standard orbital for the smaller stuff. Now I reach for my random orbital palm in most instances, even for bigger flat work.
Of the main sanding choices for general use, belt, orbital or random orbital, the random is the jack of all, and master of the majority as well.
Dealing with detail
But Intricate or inaccessible areas are tricky to deal with, calling for detail sanders. These work on a standard circular orbital pattern so aren’t huge shifters of stock or finish, but work very well in their perceived plane.
Additional finger-type accessories for other applications such as louvre slats give the tool more scope, but unless you must sand after assembly, it’s a tool that is more at home with renovation and refinishing work than new stuff built in the ’shop.
The multi-tool alternatives offer scope beyond sanding, but for sanding purposes you should primarily consider the delta function first and foremost.
Keep it on file
The final hand-held sander comes out of the metalworking industry, first turning up in the woodworking arena as one of Black and Decker’s clever promotions where they appeared to be a must-have for dads across the land (my dad had one!.). I am referring of course to the Powerfile sander. Initially for metalworking applications such as cleaning off welds and working in otherwise inaccessible areas, the woodworking blurb of the day touted them as ideal for cleaning out mortise lock recesses and similar.
In reality, removing the waste with traditional drill bits and chisels is easier, although you could, use one for easing a hole that is too tight. I see them as more a shaping tool for carvers and for cleaning up or shaping more intricate stuff.
As they operate like a big belt sander, they can remove stock at an alarming rate so don’t get too carried away. Budget models are still out there, and for the pro end, and aimed more at metal rather than wood, there are some big well-made options.