How to use a diamond hole saw
June 22, 2017


When to use a diamond hole saw

Diamond hole saws are designed to drill holes in glass, ceramics, porcelain, ceramic and porcelain tile, limestone, slate, marble, granite, stone, and fiberglass.  

Diamond hole saw drilling technique

How to extend the life of your diamond hole saw

The life and effectiveness of a diamond hole saw varies greatly based on the material being cut, the amount of lubrication used, the tools that are used and the technique of the operator. In order to maximize the life of the hole saw, these important notes should always be followed:

LUBRICATION

Always use plenty of water when using a diamond hole saw. The water is used to keep the hole saw cool and wash away any slurry generated. The point of contact between the cutting surface and the hole saw should always be wet and the hole saw tip should never be hot. If the tip is ever more than just warm, it is generally an indication of too little lubrication (or possibly too much speed or pressure). The water reduces heat build-up, prolonging hole saw life, and helps avoid heat fractures in the material. Minimal lubrication will keep the hole saw from burning up, but very good lubrication techniques will extend hole saw life by a factor of five or even 10. Also note that oil based lubricants do not work well on diamond hole saws. (See below for more detailed information.)

PUMPING TECHNIQUES

When drilling holes with a diamond hole saw, ALWAYS use a pumping technique. This technique involves easing the hole saw into the cutting surface or hole, then pulling the hole saw back to allow water to penetrate the cut, then easing the hole saw back down again (every 15 to 20 seconds or so). The water will flush out slurry that has been generated and will make sure the contact point between the surface being cut and the diamond hole saw remains lubricated. Without the pumping technique, the water will not reach the very tip of the hole saw even if the hole saw is under water.

DRILL SPEED

Since all materials vary in hardness and abrasiveness, it is impossible to determine exact drill speeds. It is suggested that users follow the recommended drilling speed, or go even slower if they are not sure about the material being cut. A faster drill speed or increased pressure may reduce the cutting time slightly, but it will also increase the friction significantly and heat up the hole saw. This will reduce the hole saw life considerably and increase the risk of heat fractures and material breakage. If a hole saw develops yellow, brown, blue or black 'burn marks' around the tip, it is an indication of extreme heat and that the drill speed being used is too fast or the amount of pressure on the drill is too great.

DRILL PRESSURE

When using a diamond hole saw it is very important to have only light to medium pressure on the drill and to let the hole saw "drill at its own speed". Increasing pressure will not speed up the cutting noticeably, but it will increase the friction considerably and quickly cause the hole saw to overheat. This not only burns up the hole saw, but it also heats up the surrounding surface and can cause heat fractures or breakage to occur. If a hole is being drilled completely through a piece of material, it is also important to "lighten up" considerably on the pressure when the hole saw is near the back of the material. This reduces chipping or fracturing on the back of the material when the hole saw emerges from the back.

TOOLS

As speed is such an important factor when it comes to the operation of a diamond hole saw, it is recommended users use a variable speed drill. NEVER should an ‘impact driver’ or ‘hammer drill’ be used with a diamond hole saw, as this will cause the tip of the hole saw to mushroom or split. When using a hole saw over ½”, it is preferable to use a drill press rather than a hand drill when a template is not available.

MATERIAL BEING CUT

The life of any type of diamond hole saw depends upon the hardness, abrasiveness, and thickness of the material being drilled and the specific drilling techniques used (drill speed, pressure and lubrication); however, the diamonds of a hole saw don't usually wear out as often as they wear off due to heat and friction caused by the extreme hardness and abrasiveness of the material being cut. By employing the strategies listed above, a user can considerably extend the life of his/her diamond hole saw. It should also be noted that in some very hard stones and tiles, it may take 2-3 minutes to drill only ¼”.

Recap: how to extend the life of your diamond hole saw

  • ALWAYS use plenty of water
  • ALWAYS use a pumping technique
  • ALWAYS use the recommended drill speed or use a slower speed
  • ALWAYS let the hole saw cut at its own speed, do not apply too much pressure
  • NEVER use an ‘impact driver’ or ‘hammer drill’; a variable speed hand drill or drill press is recommended
  • SPEED KILLS—optimal drill speeds, low drill pressure, and increased use of water will extend hole saw life considerably.

Balancing cutting speed, Drill Speed, Pressure and Lubrication

The cutting speed and life of a diamond hole saw are affected by the hardness and abrasiveness of the material plus the drill speed, pressure and lubrication. Experience with a specific material quickly allows a person to determine the optimum drill speed, pressure, and lubrication to obtain the fastest cutting speed with the least effect upon hole saw life and risk of heat fractures or breakage. However, when experience is lacking, it is best to start out with a very slow drill speed, very low pressure and lots of lubrication. This starting point reduces risks to a minimum and extends hole saw life considerably.

Recommended drill speeds

Diamond hole saws

Recommended Drill Speed (rpm)

Material/Hole Saw Size

1/2"

1"

2"

3"

4"

Fiberglass

1200

700

350

250

175

Glass, Ceramic & China

800

500

250

160

125

Limestone & Marble Stone

600

450

225

130

100

Ceramic Wall Tile

600

450

225

130

100

Porcelain Wall Tile

500

375

180

125

90

Porcelain Floor Tile

500

375

180

125

90

Granite Stone

400

300

150

100

75

(Not for use on concrete or masonry, or with hammer drills)

Recommended drill head pressure

Material

Recommended Drill Head

Pressure (lbs) *

Fiberglass

10 to 15 lbs

Limestone & Marble Stone

12 to 18 lbs

Glass, Ceramic & Porcelain China

12 to 18 lbs

Ceramic/Porcelain Wall Tile

15 to 20 lbs

Stone Style Porcelain Floor Tile

18 to 30 lbs

Granite Stone

18 to 30 lbs

Material hardness and abrasiveness

Materials have varying degrees of hardness and abrasiveness. Additionally, specific man-made and natural materials can differ greatly depending upon their exact physical compositions. For example, glass varies in hardness depending upon colour and type, since various metals and minerals are added to achieve the different types and colours. Glass also has differing degrees of "temper" depending upon the specific manufacturing methods used.

The hardness and abrasiveness of natural materials, such as stone, vary by type, but they also vary significantly within a specific type. Most stones are not pure - they are mixtures of various types of rock. Granite, for example, contains various combinations of primarily quartz, feldspar, black mica and hornblende. Therefore, a specific stone type such as granite or marble, will vary significantly in hardness and abrasiveness depending upon the exact mineral composition that varies by quarry location. For example, river sand is much less abrasive than quarry sand.

Below is a table of the hardness of various materials. The table uses the standard Knoop Hardness Scale (kg/mm2). The hardest known material is diamond, with a Knoop measurement of 7,000. Tungsten carbide, used in carbide hole saws, is the hardest natural material next to diamond. However, with a measurement of 2,000, tungsten carbide is only 30% as hard as diamond.

Material

Knoop Hardness Scale

Wood - Pine

10

Copper

120

Limestone

125 - 150

Marble

140 - 180

Slate

140 - 250

Porcelain Fixtures & China

400 - 500

Glass & Ceramic

400 - 550

Ceramic Wall Tile

450 - 550

Porcelain Wall Tile

500 - 650

Porcelain Floor Tile

500 - 650

Marble Style Porcelain Floor Tile

500 - 650

Granite Style Porcelain Floor Tile

500 - 650

Granite

550 - 650

Quartz

820

CommonTool Steel

700 - 900

Tungsten Carbide

2,000

Diamond

7,000

 

Lubrication tips and techniques

Various kinds of very specialized industrial water feed equipment are available for industrial production type work. But, when drilling with diamond hole saws, the primary concern is merely getting enough water lubrication on the cutting edge of the hole saw, no matter what method is used. All lubrication methods are not equal. Since good lubrication extends hole saw life considerably, below is a rating of the various methods.

Hole Saw

Lubrication Method

Rating

(1 poor - 10 good)

Squirt Bottle

2

Hose

3

Clay Dam

4

Under Water

4

Squirt Bottle with Pumping Action

6

Clay Dam with Pumping Action

9

Under Water with Pumping Action

9

 

With all of these methods of lubrication, it is very important to use a "pumping" technique to allow the water to reach the hole saw tip. While drilling, merely raise the hole saw up and down a fraction of an inch once in a while as you drill (maybe every 15 to 20 seconds or so). This assures that water enters the area completely and fully lubricates the very tip.

The most basic method is to use a small hose that runs water onto the surface near the hole and down into the bore hole. One trick is to place a plastic jug or bottle with a small hole near the bottom of it, next to the drill hole. The water leaks out of the bottle and provides continuous lubrication as you drill.

Another excellent lubrication technique is to build a "dam" around the drill hole using a small amount of modelling clay or a similar material. This method can be very effective. The clay can be used many times if it is stored in a plastic ziplock style bag to keep it from drying out.

For low volume repetitive work, it is also possible to place the material into a pan or plastic tub (place a thin plastic board underneath so you don't drill into the pan) and fill the pan with water so that it covers the surface of the material being drilled.

When drilling on vertical surfaces a marginally effective solution is to have someone constantly "squirting" water into the borehole using a squirt bottle or a hose.

About Exchange-A-Blade diamond hole saws

Exchange-A-Blade diamond hole saws are market leaders in quality and value. They can be used to drill holes in glass, ceramics, porcelain, ceramic and porcelain tile, limestone, slate, marble, granite, stone, and fiberglass. They are available in a variety of sizes and come in a Professional Bronze Line and an Economy Green Line. All Exchange-A-Blade diamond hole saws come with a drilling template for accurate results.

 

Some content sourced at www.DiamondSure.com and www.diamond-drill-bit-and-tool.com.