Which drill there are lots of choices but what do you really want to drill?
Sunday, March 10, 2013 5:23:16 PM Australia/Sydney
Looking to buy an electric or cordless drill and are not sure what type of drill will suit your application?
The reason there are so many different types of electric drills is there are just as many materials to drill holes into. The main materials that hole can be drilled are wood, metal and masonry. To categorise the drills there are 3 main classifications of electric drills, percussion hammer drills and rotary hammer drills which all have numerous models with different variants.
A non hammer drill or standard electric drill is as the name suggests has no hammer drill has only a rotating function which makes these electric drills ideal for drilling metal and timber. In this category of electric drill the main differential between models apart from the size or the electrical input measured in Watts is the output speed of the drills which impact’s the amount of torque. The lower the speed the higher the torque, and vice versa. To choose a high speed drill or low speed electric drill depends on t your application if you are using your electric drill for small diameter holes in metal or using spade drill bits higher speed drills are better at this application and on the opposite of the scale if you are drilling large diameter holes in metal or using large auger drill bits in timber a low speed high torque electric drill would be your best choice. This explains normal or traditional electric drills which by application only apply drive or force at 90 degrees to the direction of the whole being drilled and allow the drill to cut though and clear the material to make progress almost like a screw removing material by way of cutting or carving.
Percussion hammer drills are probably the most common type of all round drill which most people do own or have used at some point. These electric drills have both non hammer and percussion hammer functions. The Non hammer function is used the same as the above mentioned non hammer drill and the same principles apply. The reason we call hammer drills by their name is they not only turn the drill but at the same time they apply an impact action to the drill bit which in effect make the drill bit act like a chisel trying to chisel away small pieces of masonry material with each impact. This combined with the rotating action allows for a round hole to be drilled in masonry. Percussion hammer drills generate this impacting action having two gear like plates with angled teeth that don’t actually integrate or wave shaped teeth, one of these gear plates is left fixed and the other is rotated, and when rotated against each other ride up and down on each other on the highs and lows which under pressure for a an impacting action. This type of hammer action is good for use with small diameter masonry drilling for wall plugs, small diameter masonry anchors, drilling metal and timbers making them great as an all-rounder. When buying a percussion hammer drill makes sure you buy one which is suitable for your expectations buy looking at all of the drill’s capacities being a general purpose drill performing a lot functions the overall capacities in each function does become reduced. The type of drill bits you would need to use with these type of drills are round shank tungsten carbide drill bits.
Rotary hammer drills more like a compact jack hammer that has the ability to turn a drill bit instead of a drill that has an impact action. Rotary hammer drills have a much greater impact/chisel action which is generated buy two apposing pistons in a single cylinder with a hydraulic space between (to act as a cushion to ensure the piston faces don’t actually contact) allowing the driving piston to connect to a crankshaft by connecting rod and the other piston to act as an anvil striking the drill bit holder to deliver the impact for to the drill bit hence the hammer function. Rotary hammer drills are the most effective type of drill for drilling masonry especially hard cured concrete and those impossible to drill red common bricks. Rotary hammer drills use either SDS or SDS max drill bits which have a large tungsten drill bit tip shaped to quickly chisel their way through masonry material. The SDS and SDS max drill bits have extra large flutes of a slight smaller diameter to assist with removing the waste material leaving a relatively clean hole. Some rotary hammer drills three functions which allow the rotary hammer function, a straight drill function which disable the hammer function and a chisel function which is usually referred to “rotary stop” mode.
In summary always use a tool which is best suited to your application and this way if you allow the tool to its job correctly within the manufacturer’s specification you find there is little effort required from you the user and the drill will deliver years of trouble free use and very little effort from the user.