Sanders

There is a big range of sanders to choose from, and many different types. Each have their strengths and weaknesses. Some people will insist that you can only do the job right by hand, but a machine can make it very much faster in some cases!

Sander types

Type	Comments
Rotary Disc	You will be hard pushed to find a dedicated disc sanding hand tool, however it is a task that many drills and angle grinders are will suited to. A disc sander consists of a flexible backing pad that supports an abrasive faced disc (often paper - but there are other types). It is spun quickly by the tool, and one side of the disc is brought into contact with the material to be sanded.
Drum Sander	As above, few tools are available that are designed for this, however a visit to your local DIY shop will usually turn up at least one attachment for a drill that has a foam cylinder, onto which slips a sanding belt, usually fabric backed. Similar to the disk sander, but the drill body is in line with the surface to be sanded.
Orbital	The orbital sander uses a flat sheet of abrasive on a backing pad, and sands by vibrating the pad in small orbits (but no rotation). Various sizes are available to take different sizes of abrasive and suited to different sized areas.
Detail / Delta	A variation on the orbital sander, typically smaller and lighter with a smaller triangular shaped backing pad. This makes sanding into corners and other tight spaces much simpler.
Random Orbit	This looks like a cross between an orbital sander and a rotary disc sander. The disc is moved in orbits just like on a orbital sander, however it also rotates slowly at the same time. This has the effect of continuously changing the angle at which the orbital action is taking effect. The greatly enhances the sanding action and is also less likely to leave any visible marking on the finish.
Belt	Here a length of abrasive is formed into a wide fabric backed belt. This is then stretched over rollers and driven at high speed, a little like a tank track.

Uses and Results

Type	Rate of sanding	Finish achievable	Ideal applications	Comments
Disc	Very fast	Very poor - surface will have visible swirl marks from the disk, it is difficult to achieve a level finish either. Not possible to sand into corners.	Rough shaping and mouldings prior to finishing with a more refined tool.	Disc sanding is a cheap and easy way to get fast results. Special tungsten abrasive discs are available that have very long life and serious cutting ability. The quality of the machine spinning the disk will have little effect on the results although better machines will have longer endurance. Technique is everything, you need to always keep the pressure light enough to avoid the possibility of digging in, always keep it moving, lean the drill over slightly so its the side of the disc that's doing the work, and move it sideways. If you sweep it parallel to the cutting edge, gouges are guaranteed. If for a moment you allow a bit too much pressure on it, ditto. The secret is to use a very coarse fibre disc. Try 20 or 30 grit. 60 grit paper is a waste of time.
Drum	Very fast	Poor, surface may have visible lines from the drum, and it is difficult to achieve a level finish. Not possible to sand into corners.	Rough sanding of large flat areas, to remove paint, or smooth rough-cut lumber. However, smooth (though not very flat) results can be obtained if successively finer papers are used.	Drum sanding is a cheap and easy way to get fast results. It is more controllable than disc sanding, and large areas can be sanded with ease. However, dust extraction is at best very poor, generally non-existent, making use of dust masks or supplied air mandatory, and needing extensive clean-up of dust.
Orbital	slow to medium	Good to fine - best result achieved when working down through grades of abrasive	Good all round tool suitable for rough rubbing down and well as final finish work. The orbital action may however leave a slightly visible pattern of scratching on some types of material.	A wide range of tools are available here, with sizes ranging from "palm" sanders - ideal for final finish work, and larger 1/3rd and 1/2 sheet models for bigger areas. Less useful for rough shaping however.
Detail	slow	as orbital	Special purpose tool for sanding small areas and also right into corners. Note that some of the better orbital sanders will now come with extension arms that elongate the pad of the sander making the delta sander less unique in its corner sanding ability.	A moderate range of tools are available. Usually small and designed for single handed operation. The poorer ones do not sand well at all.
Random Orbit	Medium to fast	Fine finish achievable	Very good general purpose sanders. They cost a little more than orbital ones but will outperform them in most applications. With a coarse grade paper they will remove material very fast, with a fine grade they will produce a high quality finish.	Smaller range available. Poor quality examples are less frequently found however. They can be a little less controllable on small surfaces than an orbital for example. When sanding "fast", they will also eat sanding discs very quickly.
Belt	fast to very fast	Fine finish achievable	Good for when you need to remove lots of material quickly, but with controllable results and good finish. Used with fine abrasives can also give very good results. Can replace planning in some applications.	Moderate range. These cost more than most other types, The quality of construction is also more significant. Poor ones are simply not worth buying since they do not have the mechanical quality required to keep the belt running accurately and smoothly. Controlling a belt sander is not always as easy as other types (they want to run away with you in tow!), however the addition of a sanding frame can help greatly; not only giving better control, but also improve the consistency in the level of the finish. With suitable jigs they can also be adapted to bench mounting to allow more accurate sanding activities to be undertaken.

About Vibration

Most sanders produce vibration to some extent. Better quality tools make more strenuous efforts to control and minimise this. For occasional use this does not matter too much, however for prolonged use it will quickly have a noticeable effect on operator comfort and fatigue. For extended periods of use (say in the course of your job) then exposure to ongoing high levels of vibration can have serious and permanent medical effects - particularly to the hands and joints. Buying tools further up the model ranges and from the traditional "pro" tool makers is usually a good way to get tools with less vibration risk.

Dust Collection / Extraction

Sanding is one of the most innocuous DIY activities and yet is also laced with serious potential health risks if attention is not paid to dealing safely with the dust hazard. Sanding dust is particularly dangerous because of its very fine particle size. Small particle sizes can be very difficult for the bodies normal dust protection mechanisms to deal with. This can result in permanent trapping of fine particle dust in the lungs, which can go on to cause a variety of unwanted conditions. Many wood dusts are also toxic by inhalation. Inhalation of some dusts (e.g. that which can result from rapid sanding of fibreglass) can even result in fatalities after only relatively short durations of exposure.

Many sanders have a dust collection facility. This is better than nothing and will cut down the mess produced, but it is rarely sufficient to protect you from the dust hazard. To be protected you need to wear effective fine particle filter masks (or better still a respirator), and / or have very effective dust extraction from the tool. Note also that sanding dust is very effective at clogging filters in extraction / vacuum systems. Well designed high power cyclone systems can work well at collecting this type of dust.

Take care when using sanders that extract through holes punched in the paper. These holes often serve not only for extraction, but also a supply of cooling air for the sander. Block them with no punched paper and you may be rewarded with an overheated sander!

Differences

The cost range of sanders is large. The most notable thing you find with better ones is less vibration. Note also however that the low end tools are not usually rated for continuous operation (and sanding is a task that you can go at for hours at a time if the mood takes you!).

Special Mention

There are a few specialised power tools that also make good sanders, but don't directly fit into any of the categories listed above. Versatile tools like the Fein

Multi-master will make a good job of detail sanding. Many modelling sized tools (Dremel etc) also have several ways of sanding. There are also special purpose tools like some of the Festool range that allow "linear" sanding (bit like an orbital that only goes from side to side) for sanding long

straight but intricate things (like handrails, architrave, and dados for example).

Second Hand Tools

Nothing much special to look for. Take care with sanders that hold the paper via a "hook and loop" backing pad, that the backing pad has not worn out and will still hold the paper firmly. These types of backing pads need to be considered as consumable items. Sanders with dust collection may require new filters / bags.