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How to Properly Use a Hole Saw

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How to properly use a hole saw to make holes in wood and metal doors, floor joists, or enlarging existing holes.

Hole saws are one of the most useful and dangerous tools you can use for performing home improvement and carpentry projects. Knowing when and how to use a hole saw is important to complete your project safely and efficiently. Hole saws can be used for cutting through wood, metal, tile, and even glass or concrete.

Safety Precautions

For general use of electric drills review the following;

Before

  • Do not use the tool if the grounding pin on the three-pin plug is removed.
  • Check that the trigger switch works properly. 
  •  Check for loose power cord connections or damage to the cord.
  • Ensure the chuck is tightly secured to the spindle.
  • Ensure the drill bit is tightly secured and the chuck key is removed.

During

  • Avoid using a tool in damp or wet areas – if you must, provide for ground fault protection.
  • Wear safety goggles, safety glasses with side shields, or a full face shield to protect your eyes.
  • Wear a dust mask or respirator, when conditions warrant it.
  • Wear hearing protection during drill operations.
  • Brace or hold the drill securely, and anticipate the direction of torque during drilling operations.
  • If there is potential for the bit to bind while drilling, do not engage the trigger lock switch. 
  • If the drill binds, immediately release the trigger and unplug from the power source. 
  •  Do not try to free a jammed bit by starting and stopping the drill.
  • As the hole is completed, grip the drill firmly, reduce the pressure on the tool, and allow the bit to pass through the opening.
  • When drilling a deep hole, withdraw the drill several times to clean the drill bit. 
  •  Unplug the drill before changing bits, accessories or attachments.

Hole Saw Use Guide

Hole saws are most often used for installing locksets in doors, but they are also used to make holes in joists to allow pipes and wiring to pass through.

A hole saw consist of the hole saw, an arbor, and a pilot drill. On most standard arbors the ¼-in. pilot drill can be removed to change it for a sharpened bit by loosening a set screw on the shank of the arbor. Some pilot bits have a flat side on the shank which must face the set screw. The hole saw threads onto the arbor and is held in place with two retractable pins or an arbor nut.

Bi-metal Hole Saw

Arbor with Pilot Drill bit

Hole saw pilot drill bit with flat-sided shank

Set up

Mount the correct-size hole saw in the arbor. If your hole saw has an adjustable center bit, make sure it protrudes past the toothed edge of the saw about 3/8 in. If the center bit has a flat spot on its shank, align this with the setscrew. Then tighten the setscrew to secure the bit. Finally, tighten the hole saw in the chuck of a corded 3/8-in. variable speed drill. Electric drills are better suited for hole saw than cordless drills.

Drilling

1. Drill a pilot hole - Mark the center of the hole and drill a 1/8-in. pilot hole completely through the door to transfer the center to the other side. Keep bit level and square to the material.

2. Align the hole saw - Align the hole saw pilot bit with the pilot hole. Grab the drill firmly with both hands and press straight in. Run the drill slowly and adjust the angle until the hole saw teeth are contacting the wood evenly. The hole saw must be perpendicular to the wood to prevent binding.

 

3. Speed Control - Increase the drill speed and use even pressure after the teeth of the hole saw have cut a 1/8-in.-deep groove. Once a groove is made you can run your drill near top speed for drilling in wood and slow speed for metal. Slow the drill speed and back out the hole saw occasionally to clear the sawdust out of the groove and keep the hole saw cool. Drill about halfway through the material or until the pilot bit can be seen on the other side.

4. Finishing the hole - Align the center bit with the pilot hole on the opposite side of the material and complete the hole. Brace the drill against your hip for extra power and better control. The wood plug will stick in the saw and pop out the other side.

If the plug gets stuck inside the hole saw allow the hole saw to cool and try to pull the plug out be hand. Wear leather work gloves to protect your hands. If the plug will not move, use a flat screwdriver to work the plug out if the hole saw has a hole or slot on the side.

Drilling Deep Holes

If you have to drill a hole through a double floor joist for a plumbing project the technique is the same as above except for finishing the hole. Use caution when drill through floor joist as there may be unseen nails or screws. These will not damage the hole saw since they can cut through both materials, but the hole saw may grab slightly which can be hazardous if you are working on a ladder.

After the hole saw has bottomed out, meaning that the base of the hole saw has hit the wood of the floor joist, remove the hole saw and remove the plug with a wood chisel and hammer.

When drilling through floor joists it is best to use a ½-inch drill with a handle for additional support.

Remember to withdraw the hole saw every few seconds to clear the sawdust from the groove.

Remove the wood with a wood chisel or a strong flat screwdriver. You don’t have to make it smooth, just break off the wood plug so you can continue drilling through the joists.

Once you are almost completely through the joists, slow down and finish the hole.

Enlarging Existing Holes

This technique can be used with standard drill bits, but it is a must when using a hole saw due to the fact that you must have a pilot hole to keep the hole saw straight. This technique is typically used when changing mortise-style locksets to standard locksets with 2 1/8-in. bores.

1. Use a plywood scrap – To allow the pilot hole to work it has to go through a solid surface. Clamp a scrap of ¼ -in. plywood over the existing hole. Mark the location of the center of the new hole on the plywood.

2. Using this technique you can clamp another piece of plywood on the back side to prevent the surface of the wood from tearing out.

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Daniel Snyder

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