Detail sander purchasing advice: how to choose the right product

  • What You Need to Know
  • Delta sanders are small sanders with a triangular sanding plate. They belong to the category of orbital sanders and are suitable for small to medium-sized surfaces.
  • The device allows users to shape and smooth hard-to-reach areas, corners and curves.
  • Delta sanders work with an electronic motor. Either a mains cable or an integrated rechargeable battery is responsible for the power supply.
  • The greater the number of vibrations, the higher the material removal rate. With an adjustable oscillation rate, hard and soft materials can be sanded optimally.
  • Many triangular sanders suck the resulting sanding dust into a connected dust container or through a vacuum hose.

For every hard-to-reach corner

Building large pieces of furniture and other workpieces is a time-consuming job consisting of many small steps: The material is rough and has corners and edges that would interfere with the finished workpiece. It has to be shaped and smoothed. For this task, craftsmen as well as hobbyists can choose from a large number of different sanding tools in various sizes and shapes. A classic orbital sander is suitable for large surfaces.

If you want to work on hard-to-reach areas on a small or medium-sized workpiece, you should use a delta sander. This electric device can easily reach even tiny gaps. The name comes from the Greek letter “Delta”, which has the shape of an isosceles triangle and thus describes the appearance of the sanding plate. This is why the delta sander is also known as the triangular sander.

Construction and mode of operation of a delta sander

Delta sanders are similar to larger orbital sanders in terms of how they work, but thanks to their smaller dimensions they can be operated with one hand. The stick-shaped housing has a narrow handle. A sanding shoe is attached to the front at a 90-degree angle. The triangular sanding plate has edges that are curved outwards. It is equipped with sandpaper that can be easily attached and replaced with a Velcro fastener. Depending on the grit of the paper, the sander provides fine or coarse results. The plate can usually be rotated 120 degrees and is perforated.

The holes are part of the extraction function: the dust produced during sanding passes through them directly into a hoover or dust bag. For this purpose, there is either an adapter for a hoover hose or a small dust container at the rear end of the housing.

delta sander-close up sander for woodworking

The unit is driven by an electric motor inside the housing, which is powered by a mains cable at the rear end of the housing or by a rechargeable battery. Switching on the device sets the sanding surface into an oscillating motion. With some models, the number of oscillations can be adjusted.

Possibilities for use

Triangular sanders are mainly used for woodwork and restoration. They are used, for example, to refurbish old furniture, remove paint and varnish or put the finishing touches on stairs, windows and doors. They can also be used to sand the corners of parquet floors, mouldings and ornaments.

Hobbyists can use the delta sander to sand wooden figures, decorations or other workpieces. In model making, too, for example when designing landscapes, the shapes can be precisely finished with a delta sander. Powerful delta sanders with adjustable oscillation rates are also able to work on objects made of metal, plastic or glass with the right sandpaper.

Difference to other sanders

Which sander is the right one depends on the size of the workpiece and the area to be sanded. Delta sanders are just one of many sanders. They belong to the category of orbital sanders, although classic orbital sanders are larger. In addition, the large orbital sanders usually have a rectangular sanding surface and are more suitable for larger surfaces. They can also easily handle corners and curves.

So-called multi-sanders can be classified between classic orbital sanders and triangular sanders. They are similar in size to orbital sanders, but have a triangular sanding plate. Like delta sanders, multi-sanders reach difficult spots, but also on larger surfaces. Orbital sanders are usually more effective on large surfaces.

Random orbital sanders are another type of sander. Their round sanding discs are suitable for sanding and polishing rough and curved surfaces. Eccentric sanders are used for medium-sized to large workpieces. In contrast to orbital and delta sanders, the sanding plate not only oscillates but also rotates around its own axis.

Multi-sander woman sanding down window frames

There are also belt and angle grinders. Belt sanders are suitable for large to very large surfaces thanks to their endless running sanding belt. They remove a lot of sanding dust. They can also be used for cutting materials. Angle grinders have different discs and attachments: Depending on what is attached to the device, it is suitable for cutting, grinding as well as roughing work.

What to look for when buying a delta grinder

The right delta sander can be found on the basis of various criteria, such as the performance when sanding different materials, the handling as well as the quality and the processing of the materials.

The number of vibrations and the performance of a delta sander

The number of oscillations that a delta sander performs in one minute provides information about how well the device sands the materials. The higher the number of vibrations, the higher the material removal rate. Simple delta sanders only have a single vibration rate. They provide maximum power all the time. They are often sufficient for occasional use. However, if the device is to be used for different materials, a model is suitable that allows craftsmen and hobbyists to regulate the oscillation rates. This allows the power of the triangular cutter to be adjusted to the properties of the material.

Entry-level models have an oscillation rate of about 9,000 to 11,000 oscillations per minute. In the medium price range, sanders can achieve up to 18,000 oscillations per minute. Professional delta sanders reach an oscillation rate of more than 24,000 revolutions per minute. For those who regularly carry out sanding work, a premium device with 20,000 to 24,000 oscillations per minute makes sense.

Corded or cordless

Most delta sanders are equipped with an electric motor. Only a few models, mainly in industry, have a drive with compressed air.

Power is supplied either by mains cable or rechargeable battery. Battery-powered triangular sanders can be used anywhere: as they are not dependent on a power socket, they can also be used outdoors, for example in the garden. Typically, they work with a voltage of 18 volts and have a battery capacity of 2.0 to 3.0 ampere hours. However, the battery is quickly used up during longer uses, which is why a replacement battery is indispensable.

With a corded delta sander, users are tied to a specific location, but the devices can also be used continuously. A model that is powered by mains current also achieves a consistently high performance during long periods of use. To ensure that users have enough freedom of movement, a mains cable with a length of at least three metres is recommended. The power of corded delta sanders is usually between 130 and 280 watts. Models with an output of up to 400 watts tend to be multi-sander models.

The rated power is mainly important for determining the electricity costs. In contrast to the number of oscillations, the power in watts provides little information about the material removal rate. Even a 190-watt unit from Einhell can achieve 20,000 oscillations per minute.

Dimensions of the grinding plate

With delta cutters, the overall size is of little importance. More important is the size of the sanding plate. This determines how much material the tool removes and for which applications it is suitable.

With a small sanding plate, craftsmen and hobbyists can get into narrow corners with ease. However, working on a larger workpiece takes longer than with a larger plate. A larger plate means that the diameter of the circular sweeping motion is larger. Manufacturers such as Bosch usually state the value as “diameter of the oscillating circuit”. Another name is grinding stroke. Often a large diameter goes hand in hand with high power and thus favours material removal.

Delta sander sandpaper in triangular shape next to sander

The typical corner dimension of a sanding plate is about 90 millimetres. On small models, each side is only between 60 and 65 millimetres. On multi-sanders, the corner dimension is 150 millimetres. If the sanding plate of a triangular sander has a corner dimension of around 93 millimetres, the diameter of the oscillating circuit is often 1.8 millimetres.

A small sanding plate is fine for particularly narrow areas that require little power to work on. If you dare to work on larger areas, you will be more efficient with sanding plates that are at least 90 millimetres in size.

Material and workmanship

Regardless of the price range, delta sanders are made of plastic and metal. The models differ mainly in the quality of the material and its processing in the end product. The device should be robustly constructed and insensitive to impacts. The higher the proportion of metal, the longer the service life. The durability of the triangular grinder also benefits from a dust-protected ball bearing that cannot suffer damage from the abrasion of the ground workpiece.

The handling

In order to be able to work with the delta sander for a long time, it is not only the material removal that is important, but also the ease of use. If the triangular sander does not lie comfortably in the hand, the sanding work to be done can hardly be done. A switch that can be reached from both sides is advantageous so that right- and left-handers can work without problems. Thanks to soft and rubberised handles, often called soft-grip, the tool lies securely in the hand. Vibration damping reduces the strain on hands and joints. In addition, non-slip, vibration-damping handles make it easy to guide the tool so that users can work faster and more precisely.

Heavy delta sanders often have a high motor power, but the high weight quickly causes fatigue during prolonged use. However, some lightweight delta sanders have low sanding power, so it is advisable to carefully match the weight with the desired sanding power. The average triangular sander weighs between 1.0 and 1.5 kilograms.

Maximum comfort is particularly necessary for craftsmen and hobbyists who regularly use the delta sander for longer jobs. For occasional users, a simple and light model that is neither low-vibration nor particularly ergonomic is sometimes sufficient.

For safe working

Delta sanders may be small and less powerful than other power tools, but they also pose health hazards. The sanding dust can get into the eyes or lungs. Although a connected hoover or dust container sucks up a large part of the abraded material, the vacuum does not reach particles that are swirling around. Safety goggles are therefore indispensable.

Especially if the suction function of the triangular grinder works poorly, a mouth guard, for example in the form of a dust mask, is useful. Hearing protection is not necessary for short operations, as the volume of delta sanders does not exceed the 85 decibels required by labour law. However, working with hearing protection headphones protects the hearing and is more pleasant in the long run than sanding without hearing protection.

Delta grinder man working with grinder and wearing protective mask, goggles and hearing protection
With a dust mask, safety goggles and hearing protection, the workpiece can be sanded safely.

Dust extraction for the benefit of eyes and lungs

Nowadays, most vacuum cleaners are equipped with an extraction function that sucks up the dust removed during sanding through the openings in the sanding plate. For this purpose, either a hoover adapter or a dust container is integrated. The hose of a hoover can be attached to the hoover adapter. Most of the dust and other products from sanding either go into the container or via the hose into the hoover container.

The integrated dust bag on the sander provides more freedom of movement and legroom. Users do not have to drag the hose together with the hoover behind them or fear tripping over the extra cable. However, the attached dust bag has a significantly smaller filling capacity, so it has to be emptied frequently. For occasional use, a mounted bin is quite sufficient. For long uses, a hoover attachment is not only more practical, but also more effective.

Practical accessories

The selection of special accessories for delta sanders is limited. While users can buy several attachments for multifunctional devices and, for example, matching sandpaper, only sandpaper and, in a few cases, a finger sander attachment are available for triangular sanders. The latter is a narrow, elongated sanding plate that is used for narrow crevices and on slats. Manufacturers also sell spare parts such as sanding plates and dust bags. Spare batteries can be purchased for cordless delta sanders. Some manufacturers even supply a carrying case with the sander.

Sandpaper and its grit

It is not possible to work with a sander without suitable sandpaper. However, since the size and shape of sanding sheets are not standardised, there is no universal sandpaper that is suitable for all triangular sanders. Before buying sandpaper, it is therefore advisable to look at the manufacturer’s recommendations.

Sandpaper can be found in different grits: from very fine to coarse. The coarser the grit, the greater the abrasion, and the finer the grit, the smoother the surface. For the best results, sandpaper in different grits is important. It is advisable to work the workpiece coarsely at first and then gradually finish it precisely with fine-grained sandpaper.

The grit sizes are marked with a number depending on the degree of fineness: The finer the grit, the larger the number:

Grit of sandpaperSize
Coarse6 to 30
Medium40 to 80
Fine100 to 120
Very fine220 to 1,000
Extremely fineMore than 1,000

A set of sandpaper is already included in the scope of delivery of some products. It enables immediate entry into sanding work and is therefore particularly practical for beginners. However, for those who want to finish their workpieces very precisely and in great detail, a larger selection of sandpaper is necessary. In addition, the sandpaper in the set wears out over time.

With many delta sanders, the sanding disc can be rotated. As soon as the front tip of the sandpaper shows signs of wear, you can rotate the disc so that another tip of the sandpaper is in front. When this one is worn out, the last tip comes to the front. Only when all three tips are worn out do you have to dispose of the sandpaper.