TECHNICAL GUIDE - NTDT WEB
NT DIAMOND TOOLS
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TECHNICAL GUIDE
Why choose a diamond blade or bit for your job?
Diamond Tools are the fastest most cost effective solution for cutting hard non-ferrous materials. Sledge hammers, jack hammers, and rotary impact tools are slow, noisy, and create excessive dust and debris and often damage the adjacent structural materials. Diamonds reduce operator fatigue, probide clean damage free cuts, and get your job done.
How are they made?
Diamond segments or rims are made up of metal powdiaer and diamond. The metal powder are a mixture of iron, cobalt, tungsten carbide, and other metals. This mixture (bond) is mixed with diamonds about the size or coarse salt and placed in a mold. Heat (anywhere from 1700 degrees fahrenheit) and pressure is applied to form a hard dense metal part with diamond impregnated throughout. The diamond used can be natural or synthetic. Today synthethic diamond is used predominantly because size, shape and ability to fracture (friability) are controlled making performanceduplication easier.
Segments are attached to the steel center by brazing or laser welding. In brazing, silver solder is placed between the core and the segment and heated to 1200 to 1500 fahrenheit. The silver solder melts and bonds the two parts together. In laser welding the segment and steel core are fused together by a laser beam forming a strong joint. The outer cutting diameter is then ground concentric and the sides of the segments are exposed. The exposed diamonds on the outside diameter and sides of the segment will do all of the work.
TIP:
The rotation direction arrow on diamond blades helps you mount the blade utilizing the manufacturing break-in. Disregarding this arrow can cause premature pull-out of the diamonds.
The final step in the manufacturing process is tensioning. The steel core is rolled or hammered to assure the blade will run straight and true at cutting speeds. For blades greater than 14", the saws RPM should be given to the blade manufacturer, so the correct tension will be employed.
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How does a diamond blade work?
A diamond blade is a cutting system where the size and quality of the diamond and the metal matrix all play important roles. The exposed diamonds in the cutting face start chipping away at the material. As these diamonds are used they wear flat and fracture, simultaneously the material being cut erodes away the metal holding the diamonds allowing them to fall out exposing new sharp cutting diamonds. The erosion of the bond is controlled by varying the metals in the bond. Soft abrasive materials wear down the metal bond faster than hard, dense, or non abrasive materials. A diamond blade for cutting soft abrasive material must have a hard metal bond to resist erosion long enough for the exposed diamonds to be utilized. A blade cutting hard, non abrasive material mush have a soft bond to insure the bond will erode and expose new sharp diamonds to cut efficiently.
TIP:
Most manufacturers use low number specifications for soft bonds and higher number specifications for hard bonds.
HARD MATERIALS = SOFT BONDS = LOW NUMBERS
SOFT MATERIALS = HARD BONDS = HIGH NUMBERS
Always check manufacturer's recommendation before cutting
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Why do manufacturers offer different priced blades for cutting the same material?
(i.e standard line, premium line, super standard, pro series)
The greatest raw materials cost in manufacturing a blade is diamond. Add more or better quality diamond, the price goes up. By adding more diamond, the customer usually will see better cost per cut. In going from standard line to a premium line, you may add 20% to the cost (more diamond) but obtain 30-50% longer life.
TIP:
The customer's best value is usually a premium blade giving lower cost per cut (longer life).
Lets put this information together and see how to order the right blade for the job. Questions to ask:
1) Wet or Dry cutting? Choosing "wet" or "dry" is a matter of user preference or job requirement. Dry cutting diamond blades depend on airflow around the blade to prevent excessive heat build up during cutting, eliminating the need for water tanks, water hoses and wet slurry clean up. Dry cut blades are designed for shallow intermittent sawing. The best performance is obtained when the blade is periodically allowed to run up to speed for several seconds to cool. Wet cutting, the size of the blade or saw or the conditions of the job may require diamond blades be used with continuous flow of water to prevent excessive heat buildup during cutting. Using water on the blade reduces dust and helps remove cuttings. Using wet blades without water even for a few seconds can cause excessive heat build-up and damage blades.
2) Performance VS Cost: Which is more important? The initial price or total sawing cost? For smaller jobs or occasional use, a lower price blade may be more suitable. For larger jobs or regular use, a higher priced blade will actually be less expensive to use as measured by cost per cut.
3) What kind of saw or grinder is being used? What is the horsepower? What is the RPM? Masonry saw, concrete saw, high speed saw, small power hand saw, right angle grinder, floor grinder? Blades should be matched with the saw and horsepower for best results from blade and saw. Diamond blade manufacturers design products to be run at specific speeds.
4) What kind of material is being cut? Most materials will fall into the following catagories; hard, medium hard, medium soft, soft. For example in masonry, hard would be granite or quarry tile. In concrete it would be cured concrete with hard aggregate. Soft would be light weight block or asphalt. Remember hard bonds cut softer materials and soft bonds cut harder materials.
Other factors that influence choice of diamond blades:
- Compressive strenght - 3000psi or less is considered soft; over 8000psi is considered critically hard.
- Hardness of aggregate - hard aggregate dulls diamond grit quickly so the bonds used need to be softer allowing new sharp diamonds to be exposed. Softer aggregate use harder bonds.
- Size of aggregate. The size affects diamond blade performance. Large aggregate tend to make a blade cut slower.
- Type of sand. Sand can be sharp (abrasive) or round (non-abrasive)
- Amount of steel reinforcing. Diamonds have low efficiency in cutting steel. Life in steel is often half that or less of non-steel applications.
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Problem Solving Suggestions
Loss of tension
Cause: Blade blank has been overheated.
Remedy: Provide proper amount of water to both sides of blade. Check to make sure water pump is producing sufficient water and that no blockages occur in water lines.
Cause: Blade blank has been overheated as a result of blade spinning on arbor
Remedy: Tighten blade clamping disc nut and make certain that the drive pin is functioning on concrete saws
Cause: Blade blank has been overheated because of blade blank rubbing side of material being cut.
Remedy: Properly align saw to permit square cutting. Avoid twisting the blade in cut. Maintain a firm grip on material being cut. Make certain that shaft RPM is correct, so that blade operates at its tensioned speed and consequently runs perfectly straight.
Blade Wobbles
Cause: Blade mounted on a defective saw.
Remedy: Check for bad bearings, bent shaft or worn mounting arbor. Also check clamping discs to make sure they are clean, flat and of the manufacturer's recommended diameter.
Cause: Blade being run at improper operating speed.
Remedy: Make certain that bladeshaft is turning at the recommended RPM to match the tensioned speed of the blade. Use a tachometer to make certain blade shaft is turning and set at proper speed.
Cause: Blade collar diameters are not identical (uneven pressure is created on blade blank at the center).
Remedy: Use proper size blade collars
Cause: Blade bent as a result of dropping or twisting.
Remedy: Have manufacturer remove segments and rebraze onto a new blank core, if practical.
Blank Cracks
Cause: Blade flutters in cut as a result of loss of blank tension.
Remedy: See "Loss of Tension" section.
Cause: Blade specification is too hard for materials being cut.
Remedy: Use a softer blade specification to eliminate stresses which creates cracks.
Distorted Blade Blank
Cause: Inadequate or improper tightening of blade on saw mounting shaft, thereby causing arbor to force its way through blade blank.
Remedy: Tighten clamp securely.
Cause: Dropping saw head with mounted blade particularly on concrete saws. Also dropping objects on unmounted blade distorting blade blanks
Remedy: Avoid. Protect blade from abuse.
Blade Blank Undercutting
Cause: Abrading or wearing away of the steel center faster than the diamond segment. (Highly abrasive fines are being generated during cutting).
Remedy: Use as much water as possible to flush out fines generated during cutting or use wear retardant cores. Note of Caution: Wear retardant cores are not always the final answer to eliminating undercutting. Care must still be taken to provide sufficinet water to the blank area immidiately adjacent to the segment. This is especially important when making deep cuts.
Blade Worn Out-of-Round
Cause: Worn shaft bearings on masonry, concrete or stone saws. (Causes blade to run eccentric and wear out-of-round).
Remedy: Install new bladeshaft bearings or bladeshaft as required.
Cause: Engine not properly tuned on concrete saws, causing "hunting."
Remedy: Tune Engine.
Cause: Blade arbor hole damaged from previous mis-mounting.
Remedy: If all other blade parameters are in good condition, the arbor hole may be re-bored and properly bushed to its original size. (Do not employ on high speed saws. Do not rebush into clamping area of blade collars on any saw.)
Cause: Blade mounting arbor worn. A groove may have been scored on mounting arbor as a result of previous blade spinning on mounting arbor. When new blade is placed on such a worn arbor, it sits improperly and therefore runs eccentrically.
Remedy: Replace worn shaft or mounting arbor bushing.
Cause: Blade slipping on arbor shaft.
Remedy: Tighten blade collar on masonry or stone saw. Make certain drive pin is functioning on concrete saw.
Cause: Specification too hard for material, causing machine to "pound" at regular intervals, thereby wearing one half of the blade more than the other half.
Remedy: Use proper blade specification.
Arbor Hole Out-of-Round
Cause: Blade collar is not properly tightened, permitting blade to either rotate or vibrate on shaft.
Remedy: Wrench-tighten arbor nut to make certain blade is adequately secured to prevent rotation on arbor shaft.
Cause: Worn or dirty blade collars, which do not allow proper blade clamping.
Remedy: Clean blade collars, make sure they are not worn and tighten arbor nut properly.
Cause: Blade not properly mounted.
Remedy: Make certain blade is mounted on the proper diameter shaft before tightening arbor nut. On concrete saws, make certain that pinhole slides over arbor drive pin. Never depend on drive pin to actually drive the blade. A drive pin is simply a safety measure to prevent the blade from spinning on its mounting arbor, should the nut become loose. Note: Distorted blade arbor holes can be rebored, provided they are within tolerance and provided the blank has not been abused.
Blade Will Not Cut
Cause: Blade is too hard for material being cut. (improper blade specification).
Remedy: Consult blade recommendation chart or manufacturer for the proper blade specification for the material being cut.
Cause: Blade has become dull, probably as a result of being used on too hard of a material.
Remedy: Dress or sharpen with soft concrete block, piece of sandstone, or worn used abrasive grit grinding wheel to expose diamonds. Continual dressing indicates the blade specification is too hard for the material being cut.
Cause: Failure to initially break-in a new blade on specific material being cut
Remedy: Allow blade to sharpen itself on the material to be cut when first placing it on the saw. This is the proper way to break in a blade.
Cause: Insufficient power to permit blade to cut properly
Remedy: Tighten belts in accordance with machine maintenance instructions. Use correct voltage at motor and use adequate horsepower for cutting specification.
"Dry-Cutting" Diamond Blades (For your safety)
Use intermittently to allow proper air cooling on low and high speed saws. Continuous friction, causing heat buildup and retention, is still a blade's worst enemy. Check the blade frequently for signs of overheating, loss of tension or cracking.
For maximum performance, do not force dry-cutting blades through the cut. Excessive forward or side pressure on the blade can cause reduced blade life or damage due to overloading.
Diamond blades do wear out with use. Inspect blade frequently to detect steel center gullet cracking or segment undercutting. A seperated segment can cause serious personal injury.
Comply with A.N.S.I. B7. 1, B7.5 and OSHA regulations, particularly regarding the use of appoved blade quards. Wear personal protecticve equipment and use respiratory devices.
Do not use any blades that show signs of damage!!!! (Many problems encountered in wet cutting also apply to dry cutting; please review the entire booklet)
Segment Loss
Cause: On stone and masonry saws, the material was not held firmly, which caused the blade to twist in the cut and loosen the segment.
Remedy: Material must be held firmly.
Cause: Overheating due to inadequate supply of water or complete loss of water. This is usually accompanied by discolorations which apprear on the steel center in the area of the segment loss.
Remedy: Provide adequate water flow to both sides of the blade. Look for line blockages. On concrete saws, temporary complete loss of water can result from equipment running over water fed hoses.
Cause: On concrete saws steel center worn; this is a result of undercutting by abrasive fines generated during cutting. (Blank wears to a knife edge, which weakens the blank and causes a section to be seperated).
Remedy: Use sufficient water to flush fines out of cut. If generated fines are abrasive, wear retardant cores should be used.
Cause: Defectice blade collars which cause the blade to flutter in the cut or fail to adequately support the blade in perfect alignment.
Remedy: Clear foreign material from blade and blade collar clamping surfaces, or replace collars if they are worn.
Cause: Blade is too hard for material being cut causing excessive dullness and the segment separates due to impact fatigue. (This can be the cause of frictional heat which can melt the brazing solder).
Remedy: Use the proper blade specification for the material being cut.
Cause: Blade is cutting out-of-round resulting in a pounding impact.
Remedy: Replace worn bearing, re-align bladeshaft or replace worn blade mounting arbor.
Cause: Improper blade tension which produces high pressure on the segments and subsequent failure of the braze or weld joint.
Remedy: Make sure running speed of the equipment is specified when ordering blades. On concrete and stone saws the spindle speed should be checked with a tachometer, to ensure that each diameter blade is running at the manufacturer's recommended cutting speed and blade tensioned speed.
Uneven Segment Wear
Cause: Insufficient water, generally on one side of the blade, which reduces side clearance.
Remedy: Flush water system. Make certain that water is being adequately and equally distributed to both sides of the blade.
Cause: Equipment defect, which causes the blade to wear out-of-round.
Remedy: Replace bad bearings, worn arbor shaft or misaligned spindle. On concrete saws make certain the engine runs smoothly, to prevent harmonic vibrations, which in turn cause the blade to pound on a cyclical basis.
Cause: Saw head misaligned.
Remedy: Check saw head alignment for squareness both vertically and horizontally.
Cracks
Cause: Blade is too hard for material being cut
Remedy: Use blade with softer bond
Short Life
Cause: Do not use a marble or granite blade for cutting sandstone, a tile blade for cutting concrete block or a cured concrete blade for cutting green concrete or asphalt. There are specific blades designed for each particular material to give the most economical cutting. Also, avoid the use of general purpose specifications for cutting a single specific material. General purpose diamond blades are designed to cut a range of materials and since it is unlikely the operator will be cutting proportionately the proper amount of both hard and soft materials at all times, this is not the most economical method for cutting.
Remedy: Use the proper blade specification, as recommended by the manufacturer.
Cause: Inadequate water to the blade.
Remedy: Make sure water hoses are clean and free from any blockages. Approximately 2 gallons of water per minute are required to properly cool a masonry saw blade. On concrete saws, 2 to 5 gallons per minute are required and on stone saws, up to 30 gallons per minute are required.
Cause: Bad spindle bearings, worn mounting arbor or misaligned shaft.
Remedy: Replace defective parts.
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Diamond Blade Safety
Wet Cutting Do's
1) Do follow manufacturer's recommended blade specifications for material to be cut.
2) Do inspect the diamond blade for damage that may have occured during shipment or damage due to previous use.
3) Do check mounting flanges for equal diameter, excess wear and flatness. Mounting flanges must have adequate relief around arbor hole.
4) Do be sure that the diamond saw blade is mounted on a correct diameter blade arbor between proper blade flanges and is securely tightened by hand with a wrench.
5) Do check the saw for proper operating instructions.
a) All fluids are at proper levels
b) Blade shaft bearings should be free of end and radial play.
c) V-belts should be properly tensioned and pulleys checked for excessive wear.
d) Lead-off adjustment is set correctly, to allow the blade to travel straight.
e) Do operate with blade guard in place and properly secured.
6) Do be sure there is continuous water flow to each side of the blade. Gravity feed does not supply a sufficient water flow. The water pumps on concrete saws are "booster" pumps only and are not adequate as a primary pressure source. An adequate coolant supply is required for wet cutting blades to maintain blade life and cutting efficiency.
7) DO FOLLOW THE MANUFACTURER'S RECOMMENDED PULLEY SIZES AND OPERATING SPEEDS FOR SPECIFIC BLADE DIAMETERS; REFER TO MANUFACTURER'S OPERATING MANUAL.
8) Do operate saw with proper safety attire, i.e., safety glasses, safety helmet, safety shoes, hearing protection.
9) Do examine blade periodically for cracks in the steel center or segments, or excessive wear under the segments.
Wet Cutting Dont's
1) Don't use a diamond saw blade without checking manufacturer's recommendations for the material to be cut. Improper selection can cause excessive blade wear and possible damage to the diamond saw blade and/or machine and create unsafe operating conditions.
2) Don't use a new diamond blade or remount a used blade which has a core that is not flat or is cracked, which shows segment damage or loss, or which has damaged arbor hole.
3) Don't use mounting flanges on which the bearing surfaces are not clean and flat.
4) Don't force blade onto machine bladeshaft or mount blade on undersized bladeshaft. Either condition can result in unsafe operating conditions and excessive blade wear.
5) Dont mount blade on machine that does not meet the minimum requirements set forth in the manufacturer's machine operating manual.
Dry Cutting Do's
1) Do follow manufacturer's recommendation regarding specification for material to be cut and suitability for dry cutting applications.
2) Do inspect the blade for damage that may have occured during shipment or previous use.
3) Do inspect the diamond blade periodically during use for core flatness, fatigue cracks, segment damage, undercutting and damage to the arbor hole.
4) Do check the mounting flange to be sure that they are of equal and correct diameter, that they do not show excessive wear, and they are flat.
5) Do be sure that the diamond blade is mounted on a correct diameter blade arbor between proper blade flanges and is securely hand tightened with the wrench provided or an adjustable wrench no longer than 8".
6) Do check for proper saw machine conditions. Bladeshaft bearings should be free of end and radial play. Consult the operating manual from the saw manufacturer for proper machine maintenance.
7) Do follow the manufacturer's recommendation for operating speeds for specific blade diameters.
8) Do maintain a firm grip on hand-held saws during cutting operation.
9) Do wear proper safety equipment at all times. Always wear safety glasses, safety footwear, snug fitting clothing, hearing and head protection and respiratory equipment where required.
Dry Cutting Dont's
1) Don't cut dry except with a blade specifically designated for dry cutting by the manufacturer.
2) Don't force blade onto machine blade shaft, alter the size of the mounting hole, or tighten mounting nut excessively. Use of bushings to redue the arbor hole size is not recommended for diamond blades use on high speed saws.
3) Don't exceed the maximum operating speed estabished for the diamond blade.
4) Don't operate a saw without proper safety guards in place. NEVER OPERATE ANY SAW , WET OR DRY, WITHOUT A BLADE GUARD!
5) Don't stand in direct line with dry diamond or abrasive blades during start-up or operation.
6) Don't cut or grind with the sides of a diamond blade.
7) Don't force the blade into the material; allow the blade to cut at its own speed. Forcing the blade may cause overheating or blade damage.
8) Don't make long continuous cuts with a dry diamond blade. Allow the blade to cool by turning in air. The harder the material being cut, the more often the blade should be allowed to cool.
9) Don't use the blade to cut material other than that recommended by the manufacturer for that specific blade type.
10) Don't use the blade on a type of saw other than that specified by the manufacturer.
11) Don't allow the blade to deflect in the cut.
12) Don't attempt to cut curves or radii.
IMPORTANT: FOR COMPLETE SAFETY INFORMATION, REFER TO ANSI SAFETY CODE B7. 1 AVSAILABLE THROUGH THE SAW MANUFACTURER'S
Concrete Saw Safety Precautions
1) Before mounting any blade on the saw, the blade should be inspected for any damage that might have occured during shipment, handling or previous use
2) The bladeshaft collars must be of proper diameter for the size blade being used. Larger blades require larger collars. The arbor should be cleaned and examined for damage before mounting blade.
3) The blade must be properly fitted over arbor and drive pin. Drive pin must project through hole in blade and into collar. Do not force the blade onto the arbor.
4) Disconnect spark plug(s) and use bladeshaft lock pin when tightening the bladeshaft nut. Tighten the bladeshaft nut securely against the outside blade shaft collar. The blade shaft has left hand threads on the right side of the saw and right hand threads on the left side of the saw.
5) The blade guard must always be in place when the saw is running. Always use a proper blade guard of the size blade being used.
6) The operator should wear safety glasses and appropriate safety equipment at all times.
7) Never leave saw unattached while engine is running.
8) Always secure saw from rolling when not in use.
9) Do not stop the engine on a self-propelled saw while on a grade.
10) When stopping any saw on a grade, the wheels must be chocked.
11) When starting the saw, the operator should stand away from and to the side of the blade
12) If for any reason the blade stalls in the cut, raise the blade out of the cut and check the outside blade shaft collar and nut for tightness before restarting the engine. Inspect the blade for damage. Use care when resuming a cut. Make certain that the blades is in alignment with the previous cut.
13) During cutting, do not exert excessive side pressure on the handles as a method of steering. Do not force the blade into material by lowering the blade too quickly or by increasing the speed of the saw.
14) Adequate coolant must be used when sawing with wet cutting abrasive or diamond blades. Gravity feed does not supply adequate waterflow. The water pumps on concrete saws are "booster" pumps only and are not adequate as a primary pressure source. An adequate coolant supply is required for wet cutting blades to maintain blade life and cutting efficiency.
15) The blade shaft must be operated within the specified maximum operating speed.
16) Operate engine at proper RPM. Never alter the RPM or governor setting.
17) In case of an emergency, "SHUT OFF ENGINE."
Masonry Saw Safety Precautions
1) Keep the area around the saw free from debris which could call falls.
2) Prohibit the use of the saw by unauthorized or untrained personnel.
3) Keep the conveyor cart free of grit and debris which could allow the material to slip or twist during cutting operations.
4) Hold the material firmly against the backstop of the conveyor cart or guide-a-cut, keeping the fingers out of the path of the blade.
5) Position the saw on a firm, flat area and be sure that the saw will not move in use.
6) Replace blade collars if they become worn to less than 4" diameter for 18" and 20" blades. or less that 3.5" diameter for 14" blades.
MAXIMUM CUTTING DEPTH
CONCRETE BLADES
Blade Diameter.............................................Cutting Depth
12"..................................................................3-1/2"
14"..................................................................4-1/2"
16"..................................................................5-1/2"
18"..................................................................6-1/2"
20"..................................................................7-1/2"
24"..................................................................9-12"
26"..................................................................10-1/2"
30"..................................................................11-1/2"
36"..................................................................14-1/2"
42"..................................................................17-1/2"
48"..................................................................19-1/2"
HIGH SPEED SAWBLADES
Blade Diameter...............................................Cutting Depth
12"....................................................................4"
14"....................................................................5"
WALL SAW BLADES
Blade Diameter...............................................Cutting Depth
18".....................................................................6-1/2"
24".....................................................................9-1/2"
30".....................................................................11-1/2"
36".....................................................................14-1/2"
42".....................................................................17-3/4"
48".....................................................................20-3/4"
MASONRY BLADES
Blade Diameter................................................Cutting Depth
14".....................................................................5"
18".....................................................................7"
20".....................................................................8"
TILE SAW BLADES
Blade Diameter................................................Cutting Depth
6".......................................................................1-3/4"
7".......................................................................2-1/4"
8".......................................................................2-3/4
9".......................................................................3-1/4
10".....................................................................3-3/4"
POWER HAND SAWBLADES
Blade Diameter.................................................Cutting Depth
4"........................................................................1"
4-1/2"..................................................................1-1/4"
5"........................................................................1-1/2"
7"........................................................................2-1/2"
8"........................................................................3"
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DIAMOND BLADE SPEEDS
Diameter...................Typical Operating Speed...................Maximum Safe Speed (RPM)
4".............................9,500..............................................15,000.........................
5".............................7,600..............................................12,200.........................
6".............................6,200..............................................10,100.........................
7".............................5,500...............................................8,600..........................
8".............................4,800...............................................7,600..........................
9".............................4,200...............................................6,700..........................
10"...........................3,800...............................................6,100..........................
12"...........................3,200...............................................5,000..........................
12" (High Speed) ...........6,200...............................................6,200..........................
14"...........................2,800................................................4,300.........................
14" (High Speed)............5,500...............................................5,500..........................
16"...........................2,400...............................................3,800..........................
18"...........................2,200...............................................3,400..........................
20"...........................1,900...............................................3,000..........................
22"...........................1,750...............................................2,700..........................
24"...........................1,600...............................................2,500..........................
26"...........................1,500...............................................2,300..........................
28"...........................1,300...............................................2,100..........................
30"...........................1,300...............................................2,000..........................
32"...........................1,200...............................................1,900..........................
36"...........................1,050...............................................1,600..........................
42"..............................900...............................................1,400..........................
48"..............................800...............................................1,200..........................
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Bit Information
Impregnated
Bits are manufactured using a method called casting or impregnation. The matrix is fused directly to the tube during furnacing, producing a continuous crown bit.
Segmented
Bits are manufactured using diamond segments brazed to the steel tubing. Segmenting is a more expensive procedure with greater controls, producing a faster cutting, longer lasting product.
Diamonds
The cutting elements are used in a range of size, shapes, and/or concentrations. Larger sizes are best when cutting softer abrasive material and smaller diamonds perform best in harder or less abrasive material. Our bits and blades contain only premium grade industrial diamonds which have been expertly selected for their size and shape.
Starting The Hole
In many cases starting the hole presents a problem because the bit crown has a tendency to wander, particularly when starting in hard materials, or irregular or inclined surfaces, and more so when very long bits are used. The crown contacts only one spot on the surface of the material to be drilled and thrust tends to push the bit to one side. When starting a hole, a light bit load is recommended. After the crown has penetrated the material to be drilled, higher bit loads may be applied.
Water
Water must be used when drilling. Water is fed through a inlet hose, down inside of the bit, washing cuttings from under bit crown, up and outside of hole. Lack of water can cause diamonds to glaze or burn the bit, causing the bit to turn blue. Ideal appearance of water should show a milky cement slurry flowing out of the hole. When water turns clear it is a good indication of hitting rebar or too much water pressure.
Removing Cores
Breaking Cores
If you are not drilling completely through, the core can be easily broken by inserting a chisel or screwdriver into the circular kerf and prying the core to the opposite side. Use a second tool to lift core out. Removing broken core below the surface can be achieved by using one or many methods. Bent rod with 90 degree bend at one end, bent in old core bits, special core tongs and for larger cores, anchor bolts.
Removing Core Stuck In Bit
Increase water pressure and try to free core with your hands. If unable to do so, remove bit from drill, and push core gently through from top of bit with a rod. A small diameter core often breaks easily and jams in the core tube. Large cores help guide the bit. The lack of this guidance for small bits results in drill hole drifting, imposing side loads on bits. When removing lodged bit from hole turn power off and increase water supply. Using a bit wrench, try to rotate bit in both directions and lift out using feed handle. If unable to free bit, turn water off and disconnect bit from drill spindle. Use bit wrench again , rotating back and forth and rocking until free.
Bit Wear
Small diameter bits are much more susceptible to wear than bits of larger diameter. The difference is in the relationship of the crown diameter to the size of the aggregate, and materials' reinforcements. Often the drilling surface of small bits cut completely into hard quartz or flint aggregate or into rebar, which causes rapid bit wear.
Material To Be Drilled
Knowledge of the material to be drilled is important, in order to fully evaluate the drilling performance with respect to penetration rate and total footage drilled. The presence of large hard material aggregate (generally high quartz or flint content) decreases the drillability while small aggregate (sand, gravel, crushed stone) improves the drillability.
Pressure
Steady, even pressure assures true running, accurate holes, and longer bit life. Constant pressure must be applied so the bit is constantly cutting. Overloading will damage the bit and the motor. Insufficient pressure will glaze or polish the diamonds reducing cutting efficiency. When steel reinforcing rods are encountered, the needle on the ampmeter may jump slightly showing a heavier load. When you encounter rebar, lessen the feed rate to allow needle to return to normal.
Remember
The effectiveness in drilling depends on three factors
- Type of bit used
- Material to be drilled
- Capabilities of the machine
Machine Secured
It is very important that the drilling machine is properly secured to the work surface. Movement during drilling will cause chatter of bit against the work surface. Bit may also bind in hole, causing damage to the bit.