Although adjustable hole cutters have been in use for many years, the new style with a clear plastic shield for use in a hand drill is a relatively recent development. The earliest models were designs that had a single cutting blade on a bar that could be adjusted for different size holes and different lengths of bars to add to the cutting bar to provide for better balance. The twin blade design of the Hole Pro adjustable hole saw cutter is a big improvement over the single blade designs in terms of performance and durability.
With the twin blade design there are no balance bars needed and these bars with their small mounting threads are one of the key weaknesses of the single blade adjustable hole cutters. When the bars break off with the attachment threads inside the bar the hole cutter is toast. A second problem is that the balance bars do not completely balance the weight of the cutting blade and so there is a wobble action when cutting. When cutting overhead with a sheetrock or plaster ceiling the dust will often get between the center shaft and the ball bearing of the shield and cause it to jam. These problems are avoided completely with the twin blade Hole Pro design.
There are important advantages of the adjustable hole cutters, some quite obvious and others not. Being able to adjust to the exact hole size needed is increasingly important with so little standardization and so many products coming into the USA from overseas with measurements in millimeters. Instead of a 4 inch (102mm hole) a can light may need a 100mm or 105mm cutout hole. With recessed can lights there are more than 20 different cutout hole sizes needed.
Bi-metal hole saw sizes larger than 6 inches in diameter are not widely sold as no hand held drill can use them in wood. With the Hole Pro adjustable hole cutters a drill can make a hole 6 times as large as with a hole saw and make it the exact size needed. Although the cost is higher initially, being able to change out the blades in seconds and cut another 100 holes saves money in the long run and makes it easy to keep a spare set in the carry case that comes with the hole cutters.
For some materials like soft woods, veneers, plastics, and rubber, the high speed steel make finer and smoother cuts. With hard and with abrasive materials like sheetrock and plaster and Hardie and other fiber cement board products, the tungsten carbide teeth provide much better longevity. With only the two cutting blades making contact with the work piece the torque needed is much less and it is easy to cut delicate or heat sensitive materials like plastics and rubber.
Not obvious but a big advantage of the tough ABS composite plastic dust shield is that it insures a straight in cut like having a portable drill press, and it provides for control of the cutting depth. The orange knob on the hole cutter shaft can be set to limit the cutting depth to 3/4 inch and when cutting through a wall or ceiling the user knows they are much less likely to accidentally cut an electrical wire or plumbing line than when using a jab saw or a reciprocating saw with 3 inch deep saw cuts. The circular motion of the hole cutter is also less likely to crack plaster ceilings.
We have added a vacuum adapter fitting that can be used with any of the Hole Pro shields and provides for easy attachment of a HEPA vacuum to meet the new EPA lead paint rules. This is also a good feature for use when cutting holes in areas where there is the possibility of asbestos or other hazardous substance on the surface or in the ceiling or wall spaces.