DART Holesaws Neat Holes Required?


I can’t be the only one who remembers those dire DIY-rated holesaw sets we used to have not that long ago. A single arbor casting with concentric blades all fitted within each other and only “fixed” in place with a hook on the rear of the blade. They were fine for hardboard or thin plywood, but anything more demanding usually led to a lot of swearing and holes that weren’t exactly accurate. The solution was to opt for a


single professional holesaw of the right diameter for the job – not a set because that would almost need a second mortgage. These were used for cutting wood, ply and even galvanized trunking and needed a meaty drill to power them. But one of the advantages of the


DART brand is that things like professional quality holesaw sets are now available at a price that is within the reach of mere mortals, so we can start taking advantage of what is a very useful accessory. A good holesaw can be a neat and unique solution to fitting pipes, laying cables and general drilling of large diameter holes. The DART bi-metal holesaw set I was sent comes


in a neat plastic case. Each saw and arbor is fitted into a dense foam base and some soft triangulated foam in the lid prevents the holesaws etc from rattling or falling out in transit. There are thirteen pieces in the set, nine holesaws


two arbors, a reducer adaptor and a pilot drill. It is specifically aimed at electricians, with the diameters of the holesaws aimed at the most common sizes used in that trade. The largest diameter is 82mm, a size not commonly included in sets, but very popular with electricians! The holesaws themselves are


interesting to examine because clearly some thought has gone into the design. Firstly, the teeth are not all the same size and height. This may be counter-intuitive, but the teeth need to cut the material and clear the waste. Accordingly, the teeth need to be set facing outwards and of varying sizes to minimize catching and friction (of which there is a great deal generated in holesawing) The tubular hole saw bodies are heavy steel with


cobalt added for hardness, improving performance in hard modern materials like Corian. Since electricians need to cut holes in metal flashings and trunking they have to be hard enough to cut both ferrous and non- ferrous metals too. There are perforations in the sides to clear dust and dissipate heat and to lever out the core once you have finished cutting. On the top of the four biggest diameter holesaws


are five holes. The center one is threaded to take the top of the threaded arbor and pilot drill and the other four holes are needed to lock the arbor and holesaw into place firmly so that the saw can do its job. The three smallest sizes of holesaw (16mm,


20mm and 25mm) all have spanner flats at the top so that they can be loosened from the arbor after drilling – they are tightened up a lot during the friction of use. Both the arbors have head drill shanks because cylindrical shanks would simply


twist in most drill chucks – again, don’t underestimate just how much torque is applied to these holesaws as they cut.


10 ToolBUSINESS+HIRE


Independent Review by Peter Brett


So much for the holesaws and arbors, the proof of the pudding is in the drill, to


coin a mixed metaphorical phrase, so off to the workshop and the usual pile of testing materials.


Fortunately, I had a powerful, corded drill still left


with me after a previous test, so I was able to use the biggest diameter cutter supplied. The smaller holesaws, 25mm and under, I was able to use with my 18v Metabo cordless drill that has more than enough guts to cope with them. I started easily on some 12mm thick ply just to get


the feel of how the holesaws would behave, and while the cut was pretty quick it left a few splinters – the joys of plywood. I used a slower speed after consulting the handy speed selection PDF provided by DART which proved to be a very valuable guide and improved procedures immensely. Some holes through some 20mm thick softwood


with the addition of a few nails embedded in it was very successful too – the cut was quick and accurate and the nails were sliced through with no problem at all. After all, as a plumber or electrician, you may well come across embedded objects in a beam or whatever. I also used some larger sized drills on some alloy sheet, some brass sheet and a 1mm thick mild steel sheet. It took the guide point some time to drill through before the teeth of the holesaw came into play, but I was pleasantly surprised to see how the teeth actually cut into the metals, showering small metals filings as they did so. This was cutting not simply grinding!


I was tipped the wink that the big DART arbor


can mount two holesaws on one arbor. Why you might ask? Well simply because the first hole might not be quite big enough, so by mounting a second bigger holesaw behind the first, the first holesaw would serve as a guide for the second bigger one. I had to try this of course and went for broke by choosing quite a large hole for the first hole (70mm) and the 82mm holesaw for the second. It does require a bit of care, not necessarily skill, but the idea works fine. It may also be a way of creating your own wooden doughnuts! I think the keys to the relatively easy cutting power of these DART holesaws is the way in which the teeth are arranged and the bi-metal construction that ensures a sharp and longlasting set of teeth. The dust tends to be spat out fairly quickly, and since it is the dust catching in the hole that tends to cause the burning that you can get with holesaws, burning is minimized. A little bit of care and drill speed selection will usually result in a nice round neat hole with crisp edges and no burn marks. With a retail price of around £69.00 ex VAT this set is competitively priced and will stand up to trade use. A look online reveals that the DART holesaw sizes range from


14mm to 210mm (what would you use that for – to put your head through?) along with another holesaw kit suited to the plumber which means that pretty well any user can find the sizes to suit their particular needs.


Reply No. 220 www.toolbusiness.co.uk


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36