Spade Bits and How to Use Them To Cut Holes in Soft Materials

There are several ways to make a hole in any material. One of the easiest and most common methods is to use a twist drill. Twist drills can handle any material from hard steel to rock to aluminum to plastic and woods. However, if you wish to drill a large sized hole such as a 3/8th inch hole or a 1-inch hole you have to consider other alternatives.

Options

If you wish to drill larger sized holes you have several options.
  • An auger has a larger flute to help remove tips and it is available in larger diameter holes.
  • Forstner is another tool to use to cut larger diameter holes in wood and plastics. The tool has a flat bottom and a point in the center. It requires more pressure but gives a cleaner finish. The bit may be expensive.
  • Step drills have a stair stepped profile with a straight flute and are expensive and their physical construction limits the depth of the hole at a certain diameter. This tool is better suited to cut holes in thin metal sheets.
  • Hole saws feature an outer perimeter that resembles a saw blade bent into a circle with a twist drill bit in the centre.
  • Spade bits are the cheapest and most effective alternative if you wish to cut holes in wood. This could be your best alternative.

Spade Bits
Spade Bits
Always buy quality spade bits made of his speed hardened and ground steel. Also known as paddle bits, this tool has a simple design with a spade tip in the centre to keep the bit on target. They are extremely fast and will rip through wood in seconds. The construction is simple and it is easy to sharpen the edges for reuse many times unlike other tools. Another positive feature of quality spade bits is that one can drill holes to any depth, limited by the length of the tool. The downside is that it can leave a ragged hole that requires further finishing and one cannot cut an angle hole with this tool. The tool is simple enough but a lot can be achieved if one knows how to use it right.

How to Use Spade Bits

There is a method to using quality spade bits.
  • Clamp the wooden board to be drilled firmly in place.
  • One must start right. The right way to start is not at a low speed but to point the tip at the centre mark and switch the drill to its maximum speed and then advance the tool.
  • Do not push too hard. Let the edge spurs engage the wood to mark the circumference. Now you can exert more pressure.
  • Drill through completely and pull the bit out while keeping the drill switched on, else the drill will get stuck in the wood.
Spade bits are notorious for leaving a jagged exit hole. One way to avoid this is to affix a scrap piece of wood to the work piece below it and drill through with the bit. The exit hole will be clean.

One may argue that hole saws are better because they leave a cleaner edge. There is an advantage of spade bits that is not available in other bits. They are cheap and you can buy a dozen or so. Then each one can be individually ground incrementally to reduce the sizes by a fraction. One can use these bits in sequence to make a nice tapered hole that would not be possible with other tools. This comes handy when one is making round mortises into which tenons can be fitted snugly in place. 

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