Return to top Diamond Blade Speed Guidelines
| Diameter | Recommended
RPM* | Maximum
RPM**
| | 4" (102mm) | 9,075 | 15,000 | 4-1/2" (114mm) | 8,063 | 13,300 | | 5" (127mm) | 7,260 | 12,000 | 6" (152mm) | 6,050 | 10,080 | | 8" (203mm) | 5,000 | 8,000 | | 9" (229mm) | 4,540 | 7,640 | | 10" (254mm) | 3,630 | 6,115 | 12" (305mm) | 3,025 | 5,095 | | 14" (356mm) | 2,270 | 3,820 |
* Based upon the Optimum Performance Speed calibrated in Surface Feet per Minute (SFM): 9500 + 15%. Not for lapidary blades.
** Based upon ANSI B7.1 & B7.5 guidelines for maximum safe/never exceed speeds.Return to top
Diamond Blade Sawing Guidelines To optimize productivity and blade life it is important to match the material to be cut with the proper blade. The following charts provide general diamond sawing data. The Blade | Segment Bond Hardness | Cutting Speed | Blade Life | | Harder | Slower | Longer | | Softer | Faster | Shorter |
| Diamond Quality | Cutting Speed | Blade Life | | Lower | Slower | Shorter | | Higher | Faster | Longer |
| Diamond Concentration | Cutting Speed | Blade Life | | Lower | Faster | Shorter | | Higher | Slower | Longer |
| Segment Width | Cutting Speed | Blade Life | | Thinner | Faster | Shorter | | Thicker | Slower | Longer |
The Job
| Cutting Depth | Cutting Speed | Blade Life | | Shallow | Slower | Longer | | Deep | Faster | Shorter |
| Cutting Pressure (infeed) | Cutting Speed | Blade Life | | Lower | Slower | Shorter | | Higher | Faster | Longer |
| Material Hardness | Cutting Speed | Blade Life | | Harder | Slower | Shorter | | Softer | Faster | Longer |
| Material Abrasiveness | Cutting Speed | Blade Life | | More | Faster | Shorter | | Less | Slower | Longer |
| Aggregate Size | Cutting Speed | Blade Life | | Larger | Slower | Shorter | | Smaller | Faster | Longer |
McTOOLz.com, has the professional experience and product line to help you select the proper blade and cutting tool for your job. Call the McTOOLz.com Customer Service Department at 1-866-750-8665 ext. 702 for more information. Return to top
Cutting Depth Guidelines for Tile, Stone and Lapidary Blades | Diameter | Cutting Depth* | 6" (152mm) | 1-3/4" (45mm) | | 8" (203mm) | 2-1/4" (57mm) | | 9" (229mm) | 2-3/4" (70mm) | | 10" (265mm) | 3-1/4" (83mm) | | 12" (305mm) | 3-3/4" (95mm) | | 14" (356mm) | 5" (127mm) |
*Cutting depth may vary depending on the design of the saw.
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Power Requirements for Gas Generators Before deciding on a generator, it is important to consider the power requirements of the tool you need to operate, the number of tools (and accessories) you may want to operate simultaneously, and the total current consumption at any one time. Our line of saws, hand tools, and accessories operate with induction type motors These motors require approximately two to three times the normal running requirement for startup. For example, a saw motor with a stated power requirement of 1426 watts and a startup factor of 3x the normal running load will require a generator rated at approximately 4278 watts. In addition, if a water pump is being used with the saw, this will increase your startup load approximately 138 watts for a total of 4416 watts (generator requirements listed below include water pumps where noted). If you are estimating the generator requirements for a coring rig motor, remember to take into consideration the additional load of a vacuum pump if one is to be used. Another factor that must be kept in mind is that the normal running requirements are a baseline rating and are easily exceed if a motor is placed under a greater load (i.e. pushing a thicker material through the saw at a faster rate). Typically, when running a single tool on a generator, the difference between the normal load rating and startup load rating gives you an adequate buffer; but increased motor load can become a concern if you start your tools in series to lower your generator power requirements. The power ratings listed are for the current line of MK Diamond products. Please check the rating on your saw to insure you make the proper generator choice. Safety is to be preferred over sorrow. This list does not include ratings for 3 phase or 50 hertz motors. Tile Saws | Model# | Volts | Amps | Normal Load | Startup Factor | Generator Required | | MK-212 | 115 | 11.0 | 1265 W | (3X) | 4209 W* | | MK-101 | 115 | 12.4 | 1426 W | (3X) | 4416 W* | MK-101 PRO | 115 | 17.4 | 2001 W | (3X) | 6141 W* | MK-101 PRO24 | 115 | 17.4 | 2001 W | (3X) | 6141 W* | MK-115 PRO24 | 115/ 230 | 23.2/ 11.6 | 2668 W | (3X) | 8142 W* | | MK-1070 | 115 | 15.0 | 1725 W | (3X) | 5313 W* | | MK-880 | 115 | 12.4 | 1426 W | (3X) | 4403 W* | | MK-770 | 120 | 7.4 | 888 W | (3X) | 2802 W* | | MK-660 | 115 | 8.0 | 920 W | (3X) | 2898 W* | | MK-470 | 115 | 5.3 | 610 W | (2X) | 1358 W* | | MK-370 | 115 | 5.3 | 610 W | (2X) | 1358 W* | | MK-170 | 115 | 5.0 | 575 W | (2X) | 1278 W* | | MK-145 | 115 | 4.0 | 460 W | (2X) | 920 W | | MK-100 | 115 | 12.8 | 1472 W | (3X) | 4554 W* | | MK-70 | 120 | 8.75 | 1050 W | (2X) | 2100 W |
Masonry Saws
| Model# | Volts | Amps | Normal Load | Startup Factor | Generator Required | | MK-5005S | 230 | 23.0 | 5290 W | (3X) | 15998 W* | | MK-2000 | 115/ 230 | 13.4/ 6.7 | 1541 W | (3X) | 4761 W* | | MK-2001 | 115/ 230 | 13.4/ 6.7 | 1541 W | (3X) | 4761 W* | | MK-1080 | 115 | 12.4 | 1426 W | (3X) | 4416 W* | | BX-3 | 115 | 13.0 | 1495 W | (3X) | 4485 W | | MK-70 | 120 | 8.75 | 1050 W | (2X) | 2100 W |
Concrete Saws | Model# | Volts | Amps | Normal Load | Startup Factor | Generator Required | | MK-9514-E1 | 230 | 23.0 | 5290 W | (3X) | 15870 W |
Stone Saws | Model# | Volts | Amps | Normal Load | Startup Factor | Generator Required | | MK-512 | 230 | 12.0 | 2760 W | (3X) | 8418 W* | | MK-412 | 230 | 12.0 | 2760 W | (3X) | 8418 W* | | MK-312 | 230 | 12.0 | 2760 W | (3X) | 8418 W* | | MK-212 | 115 | 11.0 | 1265 W | (3X) | 4209 W* |
* Includes 138 watts for electric water pump.Return to top
What You Should Know About Stone Natural and Precast stones vary significantly in their geographic origin, mineralogical composition, and physical and mechanical properties. There are numerous types of stone to select, with each one exhibiting specific qualities of compressive strength and abrasive resistance. - Marble
- Granite
- Sandstone
- Limestone
- Slate/Flagstone
- Precast Stones
Additionally, these qualities would dictate appropriate diamond-blade selection to effectively handle cutting requirements. Your choice of stone requires a specific type of diamond Blade. General Characteristics of Stone The complex nature and variables of Natural and Precast stone make it difficult to generalize their overall physical and mechanical properties. Unless the operator has had experience in cutting a particular stone, there are methods that can help predict the stone's sawability, and so determine the "best" diamond blade. The American Society of Testing and Materials (ASTM) recognizes several physical property measurements that can identify a stone's hardness: It is recommended to review all data relating to a stone's hardness and abrasive qualities to effectively choose the proper diamond blade. No singular Property Measurement Test can define the characteristics a stone would exhibit during the cutting process. As a general reminder for stone diamond blades: tests and industry experience has documented that stone exhibiting a greater degree of hardness and abrasive resistance require softer bond matrixes. Return to top Wet Polishing Guide Polishing pads are designed to achieve a monument quality finish on all straight or shaped surfaces. The unique design of the polishing pads allows for rapid and even removal rates with minimal effort. When used correctly, these pads provide a clear advantage over all other polishing methods. Polishing Steps: - Cut or shape material to the desired surface or pattern using either a diamond blade or diamond cup.
- Using a clamping device, secure material to be polished to a proper work surface.
- Remember, polishing is a process which takes time and requires that each grit size pad be used properly to achieve a quality finish.
- Using the 50, 120, or 220 coarse grit pads, remove all rough scratches and cut marks. Smooth the surface as much as possible with these specific grit pads. The smoothing of the surface during this stage of polishing will determine the quality of the finish that will be achieved. After working the area, dry the surface to determine if all large scratches have been removed. Using a lumber crayon, rub the surface to determine the depth of the scratches remaining.
- Once all large scratches have been sufficiently removed, the finer grit pads can be used to achieve the quality finish. The fine grit pads consist of 400, 800, 1800, and 3500. If more luster/color from the polished surface is desired, use the extremely fine 8500 grit pad.
After completing the polishing process, the following steps must be followed if a mirror finish is desired: - Make a paste of cerium oxide or tin oxide using water.
- Apply paste to felt wheel.
- Run felt wheel with slight pressure against the surface to generate heat.
- After paste dries, polishing is complete.
- Wash surface with water and dry.
The surface should have a high luster or finish. If the surface appears to have small scratches, repeat step 5. Important Points in the Polishing Process: Diamond polishing pads are designed to be used solely with water to minimize the wear on the pads and prevent hazardous dust. (The use of water acts to cool the polishing pad material, flushes away grindings, and eliminates hazardous dust). Always wear eye protection at all times. Never skip grit sizes during the polishing process. Skipping grit sizes will result in an unsatisfactory finish to the stone. Diamond polishing pads wear out prematurely due to overworking of the material or by not using a sufficient amount of water. Failure to spend adequate time polishing with each grit size pad will result in an unsatisfactory finish. Selection of the flexible rubber backer pad for shaping and curved work is highly recommended. Use the rigid backer pad for the straight edge and flat face material.
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What You Should Know About Masonry Brick manufacturing today follows fundamental procedures pioneered centuries ago. However, better knowledge of raw materials and their properties, better control of firing and improved kiln designs have resulted in a superior product. The production of bricks centers around the type of clay that is used. Clays occur in three forms (Surface Clays, Fire Clays & Shales). Although they share similar chemical compositions, they will differ in their physical characteristics. All properties of brick are affected by the composition of the raw materials and the manufacturing processes. Essentially brick are produced by: (1) mixing ground clay with water, (2) forming them into desired shapes, (3) then drying and firing them. Establishing a homogenous blend is necessary before subjecting the mixture to one of three forming processes (Stiff-Mud, Soft-Mud or Dry-Press). Next, the process continues with drying, firing and cooling. Kiln firing temperatures during manufacturing graduate from 400°F to 2400°F. Hardness of Bricks There are many different types of brick (Building, Facing, Hollow, Paving, Ceramic Glazed and Thin Brick), and different scales of hardness. The strength of a unit is used to determine its durability and cutability. Both compressive strength and absorption are affected by properties of the clay, method of manufacturing and degree of firing. Most bricks have a strength ranging from 3,000 PSI to over 20,000 PSI, with the average being around 10,000 PSI. Brick may also include different size, type and volume of aggregates to further strengthen the mix. Return to top
Understanding Concrete Four essentials must be known about the concrete to determine proper diamond-blade selection. 1. Compressive Strength
The hardness of concrete is referenced by its compressive strength measured in Pounds per Square Inch (PSI). Cured concrete slabs vary widely in compressive strength; with moisture, temperature, design of mixture additives, cementitious materials and curing processes often determining their measured level of strength. The higher the compressive strength, the harder the material. Compressive Strength | Concrete Hardness | PSI | Typical Application | | Very Hard | 8,000 or more | Nuclear Plants | | Hard | 6,000 - 8,000 | Bridges, Piers | | Medium | 4,000 - 6,000 | Roads | | Soft | 3,000 or less | Sidewalks, Patios, Parking Lots |
2. Age of the Concrete
The "age" or length of curing time, greatly affects how the diamond blade interacts with the concrete. Although methods exist to accelerate the curing process, the "state" of concrete from initial pouring to a period of 72 hours and over can be defined in 3 distinct increments, and is influenced by temperature, weather, moisture, aggregate, time of year, admixtures and composition. State 1 - 0 to 8 hours
The concrete is considered in its "green state" 0 to 8 hours after the pour, meaning it has set but has not hardened completely. With green concrete, the sand in the mixture has not bonded to the mortar blend firmly and will cause extreme abrasive action once the physics of sawing begins. Further, the slurry generated by green concrete is equally as abrasive and will require special undercutting protection for the steel core of the diamond blade. Typically, sawing control joints of highways, industrial flooring, driveways, runways and similar projects is performed during this state. State 2 - 8 to 24 hours
The concrete is considered as cured 8 to 24 hours after the pour. The sand is held firmly adhered to the overall mixture. Generally, control joints established in State 1 are widened during this time. State 3 - 24 to 72
The concrete is considered as cured 24 to 72 hours after the pour. The sand is held firmly in the mortar mixture, and the overall abrasive actions and properties of the concrete are greatly diminished. Now, consideration of the aggregates, compression strength and steel content of the concrete become important factors in determining proper diamond-blade selection. 3. Aggregates and Sand
Aggregates are the granular fillers in cement that can occupy as much as 60 to 75% of the total volume. They influence the way both green and cured concrete perform. Aggregates can be naturally occurring minerals, sand and gravel, crushed stone or manufactured sand. The most desirable aggregates used in concrete are triangular or square in shape, and with hard, dense, well-graded and durable properties. The average size and composition of aggregates greatly influence the cutting characteristics and selection of the diamond blade. Large aggregates tend to cause blades to cut slower; smaller aggregates allow the blades to cut faster. | Difficulty | Average Aggregate Size | | Harder to Cut (Blade wears slower) | 1-1/2" or more | | Harder to Cut (Blade wears slower) | 1-1/2" to 3/4" | | Harder to Cut (Blade wears slower) | 3/4" to 3/8" | | Easier to Cut (Blade wears faster) | Pea Gravel (less than 3/8") |
Aggregate hardness is referenced by the Mohs Scale. This scale assigns arbitrary quantitative units, ranging from 1 through 10, by which the scratch hardness of a mineral is determined. Each unit of hardness is represented by a mineral that can scratch any other mineral having a lower-ranking number. The minerals are ranked from talc or 1 (the softest), upward through diamond or 10 (the hardest). Hard aggregates shorten blade life and reduce cutting speed.Sand composition is another factor in determining the hardness characteristics of the cement and the abrasive properties of the mortar. Three types of sand are generally used in the mixture: - River Sand (round nonabrasive)
- River Bank Sand (sharp abrasive)
- Manufactured Sand (sharp abrasive)
River Bank Sand and Manufactured Sand are more abrasive than River Sand. The more abrasive the sand is, the harder the bond-matrix requirements. Sharper, more geometrically defined sands also require harder bonds. Mohs Hardness Scale 
4. Steel Reinforcement
Further strengthening and structural integrity of concrete is accomplished by introducing concrete reinforcing steel bars (rebar), steel wire strand of wire meshing into the concrete. It costs more to cut concrete that contains reinforcing steel because cutting rates are slower and blade life is reduced. If the cross-sectional area of concrete is 1% steel, the blade life will be about 25% shorter than if no steel was present. Concrete with 3% steel can reduce blade life as much as 75%. Standard Reinforcing Bars | Metric Size (mm) | Diameter (mm) | Imperial Size (inches) | Diameter (inches) | | 10 | 9.5 | # 3 | .375 | | 13 | 12.7 | # 4 | .500 | | 16 | 15.9 | # 5 | .625 | | 19 | 19.1 | # 6 | .750 | | 22 | 22.2 | # 7 | .875 | | 25 | 25.4 | # 8 | 1.000 | | 29 | 28.7 | # 9 | 1.128 | | 32 | 32.3 | #10 | 1.270 |
Heavy Rebar: #6 Rebar every 12" on center or 2 Mats of #4 Rebar every 12" on center Medium Rebar: #4 Rebar every 12" on center Light Rebar: Wire Mesh, single mat
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What You Should Know About Asphalt Hot Mix Asphalt (HMA) is a mixture of Asphalt Cement (a petroleum-based "glue" that comprises less than 8%, by weight, the total pavement mixture) and Aggregates (various sized stones, dust, hard inert materials and sand, comprising approximately 92%, by weight, the remaining pavement mixture.) Asphalt does not cure in the sense that concrete does, and once spread and rolled; it can be cut or drilled almost immediately. Unlike cured concrete, sand in asphalt never bonds as firmly, and the slurry created when sawing will be extremely abrasive. A bond matrix similar to cutting green concrete and undercutting protection steel cores are important factors when undertaking asphalt cutting operations. Some unique factors should be observed when cutting asphalt: Hard & large sized Aggregates in the asphalt will cause the blade to cut slower. The greater the Aggregate-Sand ratio, the faster the blade will cut, but total footage may decrease. Total asphalt depth can vary. It is common to cut through the asphalt layer into the sub-base. Generally, the sub-base contains a high content of very abrasive materials such as sand, dirt, dusts and like materials. This undesirable situation causes rapid wear of the diamond blade. Chunks or broken-up asphalt to be cut often attract dirt and sand fillers within the cracks. This, too, will make the asphalt more abrasive and affect the life of the diamond blade.
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Aggregate Classification One of the key factors that determines the performance of diamond saws and drill bits is the type of aggregate in the concrete or asphalt being cut. Aggregate is defined as the stone, gravel and sand used in paving materials like concrete and asphalt. Aggregate may be crushed or uncrushed. Crushed aggregate may be limestone, granite, sandstone, traprock, etc. Sand and gravel are typically found in natural deposits, like riverbeds, stream courses or Lake Basins. Aggregate is generally divided into "fine aggregate" (passes through a No. 4 sieve, 0.187' square opening) and "coarse aggregate" (almost all of which is retained on a No. 4 sieve and may range in size up to 3' particles). While recognizing that aggregate size and type can change completely in a short distance on a given project (say highway). It is generally true that aggregates are similar in certain geographical areas. This is primarily due to local availability of one type of material and the prohibitive cost of importing anything else. This aggregate map is not intended, nor should it be used to precisely define all aggregate in a given area. Instead, it is published as a "general guide" to the predominant aggregate hardness (as it relates to sawability) likely to be encountered in the area defined by the various colors. It should also be pointed out that any aggregate can be sawed. However, the cost of sawing is usually directly related to aggregate hardness and size. This map is simply a reference tool to provide a general sense of aggregate similarity in various areas of the country. A brief description of the predominant aggregate in each state follows. 
Alabama- Aggregates vary from favorable materials such as limestone, sandstone, and blast furnace slag to hard materials such as quartzite and chert. The harder aggregate materials are found in the Central and Southwest sections of the state. Alaska- The predominant aggregates are gravel and crushed rock and would be classified as medium-hard.
Arizona- A medium-hard gravel aggregate is encountered in most of the state and a medium-soft decomposed granite in some areas in the northern part of the state. The sand content tends to be highly abrasive.
Arkansas- A medium-hard granite aggregate is encountered in the southern two-thirds of the state and a hart chert river gravel aggregate in the northern and northeastern part of the state.
California- Medium-hard gravel aggregates are encountered in the El Centro through San Diego area as well as in the northern part of the state. A medium to medium-soft aggregate is encountered in the San Clemente, Los Angeles, Paso Robles, Lancaster and Bakersfield area.
Colorado- The northern part of the state has medium to medium-soft aggregate comprised of decomposed granite. The Denver area and southeastern and eastern sections have medium-soft decomposed granite, limestone and gravel. The Colorado Springs area consists of a medium-hard gravel.
Connecticut- Generally the aggregates consist of medium to medium-hard traprock and dolomite.
Delaware- The major portion of the state contains medium-soft traprock and limestone aggregates. The Wilmington area does produce a medium-hard gravel aggregate.
Florida- Generally the aggregates are composed of soft shell and argillaceous, siliceous and dolomitic limestone. The northern area sometimes uses hard Georgia and Alabama aggregates
Georgia- Aggregates in the northern part of the state are medium-soft sandstone and limestone. The southern three-quarters of the state has medium-hard to hard granite, schist, gneiss, and quartzite aggregates.
Hawaii- Aggregate conditions throughout the islands are of the medium-hard, basaltic type. Idaho- Generally medium-hard crushed stone and gravel aggregates.
Illinois- Aggregates in this state may be divided into three sections, the northern area medium to hard gravel, the central section medium gravel and limestone, the southern area soft limestone.
Indiana- The state has generally soft crushed limestone except in the southern and northwestern sections where medium-hard Ohio and Wabash river gravel occur.
Iowa- In the Des Moines and central Iowa area medium-hard pit and river gravel are typical. Aggregates found in the eastern, central and southwestern sections are soft limestone. The eastern border along the Mississippi River has hard chert river gravel. Medium-hard pit gravel with quartzite is found in the northwestern section.
Kansas- The aggregate conditions generally found are soft limestone. Medium-hard limestone, dolomite and hard chert gravel are found in the southeastern section, and medium-hard pit gravel in the north central area.
Kentucky- Approximately 90% of the state has aggregates of medium-soft limestone and sandstone. The northern section along the Ohio River has medium-hard quartzite river gravel.
Louisiana- Aggregate conditions in the state range from soft shell to hard chert. Maine- In general a medium-hard dolomitic gravel and some traprock are encountered in this state.
Maryland- About 60% of the state has medium-soft limestone aggregate. The balance of the state has a medium-hard river gravel.
Massachusetts- The aggregate generally found is medium traprock except in northern section bordering New Hampshire where the aggregate is medium-hard.
Michigan- Generally medium-hard glacial gravel is found. The Pontiac, Flint, Mount Clemens area contains fair amounts of hard chert or flint.
Minnesota- Aggregate in the central and northern part of the state consists of medium-hard glacial gravel. In the southern section medium-soft quarried limestone prevails.
Mississippi- Hard and medium-hard aggregates are found in the southwest section of the state and consist of the chert and quartzite.
Missouri- Soft limestone aggregate predominates in this state with a hard chert aggregate in the St. Louis area (Meramec River gravel) and a similar hard flint aggregate in the Joplin area.
Montana- The eastern section is a hard aggregate area, the Great Falls area contains a medium-hard gravel and crushed stone aggregate and the Glasgow and Miles City areas have a hard quartz and chert aggregate.
Nebraska- Eastern and Central sections contain a medium limestone and gravel mixture and the Western areas have a straight medium-hard gravel aggregate.
Nevada- The predominant aggregates are medium to medium-hard gravel and crushed decomposed granite.
New Hampshire- Generally medium-hard to hard granite gravel aggregates are encountered.
New Jersey- The predominant aggregates are a medium traprock and a hard river gravel.
New Mexico- Northern areas contain medium-soft aggregate shipped in from Colorado. A medium limestone with some quartz aggregate is encountered in the southern part of the state (Gallup, Alamogordo, Deming and Lordsburg). The Tucumcari area has a medium-hard gravel aggregate. A medium-hard to hard gravel is encountered in the Albuquerque area.
New York- There are three predominant aggregates in this state, a medium-soft limestone, medium traprock and medium to medium-hard granitic gravel.
North Carolina- Medium-hard and hard aggregates exist throughout the state and consist of granites, schist, gneiss and quartzite. There is some scattering of a medium limestone.
North Dakota- In general a medium-hard glacial gravel is encountered consisting of limestone, granitic gneiss, basalt, quartzite and chert. In the eastern half of the state the aggregate combinations are medium-soft.
Ohio- Generally a medium-soft pit gravel is encountered throughout the state except in the areas along the Ohio River where a medium-hard river bed aggregate is used.
Oklahoma- Soft limestone is generally encountered except in the western section where a medium-hard granite aggregate is used.
Oregon- The western section contains a hard granite aggregate and on the east side of the mountains a medium crushed gravel is encountered.
Pennsylvania- Generally medium-soft limestone and medium traprock aggregate are encountered except in steel mill areas where soft slag might be used. Pit gravel is commonly used in the Philadelphia area.
Rhode Island- A medium hard traprock aggregate is generally used throughout the state. South Carolina- Predominantly the aggregates consist of a medium-hard quartzite, granite and gneiss with some limited amounts of medium-soft crushed limestone and marble.
South Dakota- There are three types of aggregate encountered in this state. The eastern area consists of hard quartzite aggregate, the central portion has a medium-hard gravel aggregate and soft limestone aggregates in the western section.
Tennessee- In general medium-hard aggregates are encountered throughout the state with some medium quartzite west of Nashville and hard chert aggregate along the Mississippi River.
Texas- The predominant aggregate encountered consist of medium limestone and dolomite with a medium-hard quartzite around the San Antonio area and hard chert along the Coast area.
Utah- Aggregates consist of medium gravel throughout the state.
Vermont- In general medium to medium-hard granitic gravel aggregate is encountered throughout the state. Large aggregate is often encountered.
Virginia- Medium-hard granite gates are normally encountered throughout the state with medium-hard to river gravel in the Norfolk and Washington D.C. areas.
Washington- Medium to medium-hard gravel and crushed stone aggregate encountered on the eastern side mountains and hard gravel aggregate on the western side and in the Seattle Tacoma areas.
West Virginia- The predominant aggregates consist of a medium limestone, except along the Kana where medium-hard to hard river aggregates are used.
Wisconsin- The southern section state contains medium-soft limestone gravel aggregates. The northern have a medium-soft glacial aggregate.
Wyoming- Medium to medium-soft stone and crushed rock are encountered throughout the state. Return to top
Factors Influencing Diamond Core Bit Performance Material Hardness----------Net Result to Performance
Harder Material Drilling Speed:Slower Bit Life:Longer
Reasons for Performance Change:
Harder materials are less abrasive. They are cut into small, fine particles that don't wear the matrix. Since new diamonds aren't exposed, coring speed goes down and bit life goes up. Softer Material Drilling Speed:Faster Bit Life:Shorter
Reasons for Performance Change:
Softer materials get ripped apart by the diamonds. Those edges are larger and coarser getting through the material quicker, but shortening bit life.
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Aggregate Size-------------Net Result to Performance
Smaller Aggregate Drilling Speed:Faster Bit Life:Shorter
Reasons for Performance Change:
Aggregate is denser than concrete. Small pieces take less time to core through. Bit life is shorter because the aggregate chips off into sharp edges, the matrix drops the diamonds. Larger Aggregate Drilling Speed:Slower Bit Life:Longer
Reasons for Performance Change:
Large aggregate takes longer to core through, bits last longer because the cuttings from the aggregate come off in smaller, finer pieces causing less matrix wear.
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Material Abrasiveness------Net Result to Performance
More Abrasive Drilling Speed:Faster Bit Life:Shorter
Reasons for Performance Change:
Abrasiveness causes matrix wear. This exposes more diamonds that may fall from the matrix before they wear out. Less Abrasive Drilling Speed:Slower Bit Life:Longer
Reasons for Performance Change:
Lack of abrasiveness retards matrix wear, fewer new diamonds are exposed. The bit lasts longer but cuts slower.
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Embedded Steel-------------Net Result to Performance
Light Steel Drilling Speed:Faster Bit Life:Longer
Reasons for Performance Change:
Cutting through steel which is very tough and dense compared to concrete wears a bit very quickly. Decreasing the amount of steel improves cutting. Heavy Steel Drilling Speed:Slower Bit Life:Shorter
Reasons for Performance Change:
To cut heavy steel reinforcement you can increase pressure and/or RPMs. Alternately you can decrease water flow or add sharp silica sand into the hole. All decrease bit life.
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Matrix Hardness-------------Net Result to Performance
Harder Matrix Drilling Speed:Faster Bit Life:Longer
Reasons for Performance Change:
A harder matrix slows the controlled erosion of exposing new diamonds. Softer Matrix Drilling Speed:Slower Bit Life:Shorter
Reasons for Performance Change:
Bit life decreases because of faster matrix erosion. Diamonds fall out before they wear out.
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Water Volume----------------Net Result to Performance
Less Water Flow Drilling Speed:Faster Bit Life:Shorter
Reasons for Performance Change:
Causes the cuttings to remain in the hole; this exposes more diamonds giving a faster coring speed, but shorter life. More Water Flow Drilling Speed:Slower Bit Life:Longer
Reasons for Performance Change:
Too much water retards matrix erosion and may lead to bit glazing.
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Motor Speed (RPM)-----------Net Result to Performance
Lower Motor Speed Drilling Speed:Faster Bit Life:Shorter
Reasons for Performance Change:
Cuttings/slurry not cleared from hole. The cuttings expose new diamond edges that cut fast and wear fast. The diamonds are in contact with the concrete longer so they cut faster. Higher Motor Speed Drilling Speed:Slower Bit Life:Longer
Reasons for Performance Change:
The matrix becomes glazed with higher than recommended RPMs*, thus affecting cutting speed. Less contact time with the concrete decreases cutting.
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Bit Feed Rate (Pressure)-----Net Result to Performance
Lower Feed Rate Drilling Speed:Slower Bit Life:Longer
Reasons for Performance Change:
Low pressure allows the bit to glaze. Bit life goes up, performance goes down. Higher Feed Rate Drilling Speed:Faster Bit Life:Shorter
Reasons for Performance Change:
High pressure exposes new cutting edges that cut faster but the diamonds may fall out before they wear out. Excessive pressure may cause the crown to collapse. *Recommended RPM based on 9,500 SFPM Return to top
Sharpening Procedure for Diamond Core Bits Diamond core bits must maintain good diamond exposure in order to work efficiently. Many factors work in unison to provide the controlled erosion cycle of the bit's segments. When this controlled erosion cycle is altered, the bit can become dull or glazed. Glazing becomes noticeable when the coring feed rate slows dramatically or the bit does not cut. Examine the bit immediately. If the diamonds are flush with the metal, they are underexposed or glazed. The following steps will often correct this problem:
- Reduce water flow until it becomes very muddy. Continue using as little water as possible until penetration increases.
- If bit does not open up, remove from hole. Pour into kerf a thick (1/4") layer of silica sand, the coarser the better.
- Resume coring for approximately 3 to 5 minutes with very little water and at a lower RPM if possible.
- Gradually increase water flow to flush sand from kerf.
- Repeat as needed.
Return to top Trouble Shooting Diamond Core Bits Glazing (bit stops drilling or is very slow) | Cause: | Too much feed pressure | | Remedy: | Open bit with abrasive material (sand pot, concrete block, chop saw blade). Reduce feed pressure. Use of an ammeter will help to control speed and pressure. | | | | | Cause: | Aggregate is too hard | | Remedy: | Use a softer bond |
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Bent Segments
| Cause: | Too much feed pressure and not enough water | | Remedy: | Repair the bit if possible. Ease up on feed pressure and increase water flow. | | | | | Cause: | Aggregate is too hard | | Remedy: | Use a softer bond |
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Lost Segments | Cause: | Steel reinforcing rod | | Remedy: | Ease up on feed pressure (watch ammeter). Use a higher quality bit and increase the water flow | | | | | Cause: | Not enough water to properly cool the bit | | Remedy: | Increase water flow | | | | | Cause: | Drill rig is not properly anchored | | Remedy: | There are three ways of anchoring a rig - standing on the rig is not one of them! |
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Core Hangs Up | Cause | Not enough water to remove slurry | | Remedy | Remove bit and drive core out with a spike through the hub. Increase water flow | | | | | Cause | Core barrel is dented because of hammering on it to remove hung up cores | | Remedy | Repair the barrel and increase water flow |
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To Remove a Stuck Bit
STEP 1
Disconnect the core rig from the bit.
STEP 2
Thread a piece of threaded rod the same diameter as the bit (5/8-11 or 1-1/4-7) through the hub until it hits the concrete. Then place two hex nuts on the rod and lock them against one another so that they in turn lock themselves to the rod.
STEP 3
Turn the nuts with a wrench which will turn the rod which will in turn push against the concrete core, pulling the bit from the hole without damaging it. Return to top Diamond Core Bit Speed Guidelines
Wet Bits
| Diameter (inches) | Diameter (mm) | Max/Min RPM* | | 1" - 2" | 25mm - 51mm | 1200 - 1000 | | 2-1/4" - 5" | 57mm - 127mm | 1000 - 500 | | 5-1/4" - 12" | 134mm - 305mm | 500 - 250 |
Dry Bits | Diameter (inches) | Diameter (mm) | Max/Min RPM* | | 1" - 1-1/2" | 25mm - 38mm | 6000 - 2300 | | 1-3/4" | 44mm | 5000 - 1600 | | 2" - 2-1/4" | 51mm - 57mm | 5000 - 1200 | | 2-1/2" | 64mm | 5000 - 800 | | 3" - 5" | 76mm - 127mm | 5000 - 700 | | 6" | 152mm | 5000 - 600 |
*Based upon the Optimum Performance Speed calibrated in Surface feet per Minute (SFM). Return to top | 
