There are hundreds of power tools to choose from yet all over the country stonemasons are risking injury by tampering with guards and modifying the tools they have. Consultant Phil Mist reports.

With my personal experience of power tools and accessories stretching back almost 40 years, especially in relation to abrasives and diamond blades, and being well known in some parts of the industry (I am General Secretary of the Hire Trade Alliance) I was asked to visit a stone restoration company to advise on which grinder to use, which accessories to fit and how to use the tools legally yet still complete the task at hand. I was asked to help because there had been two accidents involving grinders at the company. When I visited and discovered how they were using their grinders I was horrified.

The list of breaches of the various regulations, the disregard of the various ACOPs (approved codes of practice) and the lack of good working practices was extensive. Guards, fittings and blades were being modified by operators at will and the faces of blades designed only to cut were being used for smoothing.

I was then completely stunned to be assured that what this particular company was doing was not uncommon in the industry.

At least this particular company had realised it had a problem and wanted to improve – and it has already changed its work practices and identified new products that are enabling it to carry out the tasks it needs to successfully and safely.

I am currently talking to the major power tool companies about them highlighting the problems through their various field sales forces and have spoken to Stone Federation Great Britain. Peter Robertshaw, the Federation’s new health & safety consultant, says he will include issues relating to the safe use of power tools in the four health & safety roadshows that the Federation intends to hold for members this year.

The problems at the stonemasonry restoration company I visited stemmed essentially from a lack of appropriate operator training – it is a problem many UK industries suffer from.

For hundreds of years the UK stone industry used hand tools almost exclusively and it is expert in using them. But the industry has now adopted a wide range of portable electric tools in a bid to complete tasks quicker and, therefore, at a lower cost.

There is nothing wrong with that but some age old techniques are not easily accomplished with modern rotating power tools. Without training, the provision of which often goes down badly with experienced workers, cutting and shaping blocks of stone with power tools can be a dangerous business, resulting in damaged tools and injured operators.

The inadvertent (or possibly deliberate) misuse of power tools, especially angle grinders, cannot be excused because it is an employer’s responsibility to provide suitable on-the-job training for operators and it is the responsibility of the operators to use the tools correctly when they have been shown how to do so.

Mechanisation of industry and regular advances in machinery and tool design have resulted in a lack of specialist knowledge due almost entirely to a lack of suitable training. It is not sufficient for an operator to read an owner’s or user’s manual – which, in any event, rarely happens.

Today’s power tools are, when compared with those of 30 years ago, advanced and powerful pieces of kit that can include a number of safety features (such as double action switches and electronic speed controls) that actually require the operator to exercise knowledge and skill in the use of the tool.

The addition of safety features such as the safety clutch in rotary drilling hammers has proved hugely beneficial. But making the tools safer has, conversely, encouraged the manufacturers to increase the size, operating capacity and power output of their machines. It is natural for manufacturers to push the boundaries but more power can lead to greater potential danger.

Some years ago one well-known power tool manufacturer was so worried that one of its powerful 230mm diameter angle grinders would fall into the wrong hands that it actually restricted sales to professionals.

Companies that purchase more powerful machinery or tools are often told they will get the job done more quickly, then forget that their operators might need some instruction about how to use the tool so they don’t hurt themselves or wreck the tool or the workpiece.

Firms often merely expect their operators to learn for themselves the right way to use a particular tool. This can lead to some decidedly bad practice, occasionally with disastrous results.

Of course, training costs an employer both time and money, often when both are in short supply – especially at present. But the expertise of operators must be a priority for all employers, particularly in industries such as stonemasonry where the power tools might be operated in ways that defy logic and safety because they are being asked to do something that was not considered when they were designed.

There have also been many improvements in the design and performance of the actual tools used with the power units – the cutting, polishing and milling heads – especially with the development of diamond technology. Many accessories not only work faster but can also achieve results that could only be dreamed of a few years ago.

The stone industry, especially in the restoration sector, has a reputation for high quality workmanship. It is something of a traditional industry with many of the methods used dating back hundreds of years.

But several types of power tools have been adopted by the industry, including hand held angle grinders. The slightly old-fashioned Abrasive Wheels Regulations training is barely of any use to workers in the stone industry since the machines are being asked by the stone industry to complete a number of tasks for which they were never intended. A ‘Correct and Safe Use of Power Tools’ training course under the Abrasive Wheels Regulations could potentially result in the removal of all angle grinders from many stone companies’ tool portfolios.

Potential danger lurks every time a power tool is used. And when the operation and accessory have not been designed for the particular task then the dangers are multiplied ten-fold.

My recent observations of angle grinders being used in the stone industry have highlighted a large number of important hazards, the elimination of which is vital. The fitting of a standard, relatively inexpensive diamond blade to a 230mm diameter 2,000W angle grinder with an adapted M14 threaded boss fastened to one side of the blade, and not the regulation inner flange and lock nut arrangement, and then using the face of the diamond blade to smooth off a flat surface of a block of stone is illegal. It is also extremely dangerous. While full details of each incident are difficult to identify, this practice seems to have resulted in several recent incidents and some injured operators.

The use of the faces of diamond blades designed for cutting infringes a number of regulations. The blades recently seen being used in this way were not marked in any way (which is illegal), the mounting method can be dangerous (depending on the blade), the application is dangerous and the guards on the machines had to be machined in order to accept the blades (which, again, is illegal).

As if this were not enough, the operators were using the machines in a dangerous fashion, having never been trained properly. Using angle grinders in this way might (or might not) speed up the process but, I would suggest, even if it does it is at an unacceptable cost.

The Stone Federation and the stone industry as a whole needs to step back and take stock of what is happening then take drastic action to change some of the current practices. There are safe ways of operating these tools within the stone industry without losing any efficiency.

Stone Federation has indicated it is willing to look into this cause for concern which can only help in ridding the industry of some of the more outlandish and more dangerous operating methods currently in use.

More from Flex

New from Flex is the RE14 Retec 1,400W universal finishing tool, which carries discs with a maximum 115mm diameter and milling heads up to 80mm at a no-load speed of 1,800-5,200 rpm. It carries a price tag of less than £470.

It weighs 3.1kg and comes with a SoftVib vibration dampening handle as standard. It also has the option of using a dampening element between the spindle and the tool for further reducing vibration as well as improving guidance and increasing the life of the machine.

It has the latest VR microprocessor control that enables speed selection with soft start and tachogenerator constant speed control. There is restart protection after a power failure, overload protection and temperature monitoring.

The gearbox is designed to give high torque in the medium- to low-speed range. There’s a large dust extraction cross section for effective dust reduction when a dust collection system is attached using the Flex rapid connection clip system.

Using standard M14 tool fixings means the RE14 can carry a large number of tools and as well as being used on stone it can be used as a scourer or planer for concrete and a sander on wood.

Also from Flex is the CS60 1,400W wet stone saw that carries 170mm discs. Maximum cutting depth is 60mm (54mm with the guide rail). It can cut up to 45º mitres of 5-44mm depth (0-38mm with the guide rail). It has a no-load speed of 6,200rpm and weighs 4.5kg.

It has high-quality magnesium die-castings for protective cover and base plates and rubber motor protection to prevent the direct intake of spray water. A GFCI operator protector circuit-breaker is integrated in the cord.

One of the Flex favourites is the LE12 wet polisher. Carrying 115mm discs with M14 connections, this 1,150W tool that has a no-load speed of 1,200-3,700rpm weighs 2.4kg. It has VR full-wave electronic control for constant speed control, soft start, overload protection and speed selection.

It has an unobstructed grip area directly above the backing pad and a grip hood for easy handling and precise working, as well as a bail handle for secure grip when working on vertical surfaces. The latest development is a water feed and control system located below the housing, which makes precise dosing easy. A special 2m hose requires no extra safety devices.

Makita has the answers

When stone sculptor Shawn Williamson, FRSA, wanted to turn a seven-tonne block of hard red Stoneraise sandstone into a larger-than-life creation of Lang Sandy Armstrong for Rowanburn on the borders of Scotland and England, he turned to Makita power tools.

Lang Sandy was a legendry ‘border riever’ at the turn of the 16th/17th centuries – hero to some, murderous villan to others.

Shawn says his first choice for hammer drills, grinders, core cutters and polishers is always Makita, while Makita says working stone is part of its heritage, with a product range that not only includes the tools Shawn uses but also saws, disc cutters, wet and dry polishers and vac units.

To create this heavyweight stone sculpture Shawn knew that he would require the help of some rugged power tools and turned first to a Makita HM1213C AVT demolition hammer for the roughing out. An HM1213C AVT is capable of producing 26joules of impact energy and between 950 and 1,900 blows per minute. He continued with a 230mm GA9020KD angle grinder and a 125mm 9555NB angle grinder for the detail and more delicate work.

For the more typical type of stonemasonry project – especially, perhaps, involving renovation – an HM1213C AVT would pack a bit more of a punch than was required and the stonemason might turn instead to a versatile tool such as the Makita

S-Mak32 for stock removal when producing replacement masonry. This is an 850W rotary hammer that delivers 4.9joules of impact energy and up to 3,300 blows per minute.

This 5kg hammer features the Makita patented Anti Vibration Technology (AVT), which uses the air generated by the piston movement to move counter weights that dampen out the impact vibration and reduce the risk to operators of developing HAVS, not to mention helping to comply with the law regarding exposure to vibration.

AVT, coupled with the fulcrum mounted rear grip handle, makes the S-Mak32 one of the safest power hammers available.

The S-Mak32 uses the SDS-Plus drill and chisel shank system, has three modes of operation – rotary only for drilling and up to 90mm TCT cores, rotary with hammer action support for heavy drilling, hammer only for pure chisel work – and is available in both 110V and 240V versions.

A wet stone polisher will produce the finest finish and the Makita PW5000C is a 900W 110V tool that uses a 100mm diameter pad and runs up to 4,000rpm. It has a built-in water line with tap that carries the water directly to the pad head.

The Makita angle grinder range runs from 100mm wheel size up to 230mm wheel size and from 710W up to a 2,400W grinder that has a soft-start system to avoid the torque load that would make it hard to hold the machine steady when you switched it on.

Many Makita angle grinders also feature the Super Joint System (SJS), where a clutch disengages the motor drive if the wheel should get jammed.

The Makita 9565CVL orbital grinder polisher has a 125mm wheel and will run up to 6,800 orbits per minute for the finest finish.

Another health hazard for stonemasons is dust and Makita has recently introduced two new L-class approved dust extractors, one with a 20litre capacity and the other with a 35litre volume.

Both are powered by a 1,100W motor and are available in 240V or 110V modes. They are equipped with the washable PET filter that gives 3,000cm² of filtration surface. An integral and easy-to-operate manual filter cleaning system is provided.

These powerful extraction units generate a maximum airflow of 3.6m² per minute and a maximum vacuum pressure of 18kPa.

Both models have a power take-off point that enables them to be coupled with Makita power tools. When the tool is started, the dust extraction unit also starts working automatically.

Fleece filter bags mean moist debris can be collected without damage to the bag. The 3.5m long flexible suction hose has a reliable click-connection system to make it easy to change the various tools and hose extensions available.

These lightweight, compact machines are easy to transport in the van and on to site. The 20litre unit stands just 500mm high and weighs only 7.3kg, while the 35litre model weighs 8.2kg and stands 685mm high.

These L-classification dust extractors are ideal for stones with low levels of silica, such as limestone. For high silica content materials, such as sandstone, granite and engineered quartz, Makita have the 447M, an M-classification extractor.

These are just some of the options available from the extensive Makita range that now encompasses more than 400 tools.

Developments in flexible drives

Flextol are still making new machinery at their factory in Leicester and selling it into the stone industry, as well as providing their customers with a repair and spares services and the KGS range of diamond products.

Many in the stone industry have a single speed Flextol machine – the ST80 – that they might only use for sanding because those who wet polish with the conventional magnesite wheels and felt with putty powder have generally used the ST/IVS infinitely variable speed unit so that the low revs needed for the felt can be used.

But Flextol say that with the new generation of Velcro-backed resin-bonded diamond pads, the single speed machine is really coming back into its own. It is lightweight and can run for hours without any danger of burning out. It is quiet and operates with low vibration, which Flextol like to contrast with angle grinders.

“Customers with these single speed machines could easily bring them back into commission by using diamond pads for polishing,” says Stuart Marshall of Flextol.

A flexible drive percussion hammer is now offered by toolmakers

G Gibson in Leeds. Made by Gelma Tools in Italy (and pictured below), these low vibration hammers only have to be plugged in to start working. They can save a lot of space and do not cost much in setup costs compared with pneumatic hammers, although they were originally designed for carving wood and are best suited to softer stones.

Gibson believe the Gelma hammer will prove popular as a gentler alternative to pneumatic hammers such as the Bon Accord made by Kelso Tools in Scotland and sold to the stone industry by tool distributors Combined Masonry Supplies and Harbro.

Bill Donald of Kelso Tools has been promising a dampened vibration version of the Bon Accord hammer for some time. He says it is now almost ready and that it will be launched this year.