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PHQ250 ROCKDRILLS

OPERATING MANUAL

PHQ250JHMAVL Anti-Vibration JacklegPHQ250JHML Standard & Muffled Jackleg

HOW TO DRILL A DRIFT ROUND

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Before beginning the miner will mark up theface of the drift or tunnel according to sizewith a grid that pinpoints the location foreach hole to be drilled in the round. The“line” (direction) for the drift round Is usuallypredetermined by engineering and sighted infrom “line plugs” installed by surveyors. Anine foot high by twelve foot wide headingwill usually have five vertical lines spacedthree feet apart and four horizontal linesspaced three feet apart. A blasthole is to bedrilled at the intersection of each line ofthese lines. Here the driller is indicating thehorizontal line marked for the “back” holes.

Marking up the round starts from thecenterline painted on the face from the lineprovided by surveyors. Here the driller isindicating the intersection of the line for the“breast” holes where it meets the center line.The star indicates the center of the driftround. The “cut” is always drilled betweenthe horizontal line for the “breast” holes andthe horizontal line for the “knee” holes ineither of the two squares having one side asthe center line. It is normal practice toalternate the area where the “cut” is to bedrilled each time a new round is drilled to beon the safe side and avoid any “bootleg”holes from the previously blasted round.

The mining act prohibits collaring holes near“bootlegs.” The driller indicates where the“burn cut” is to be drilled. This area is whereit is easiest to collar and drill holes and nearthe center of the “round” so the blastingsequence can radiate out from the “cut.

The six holes that make up astandard “burn” cut areindividually painted on the rockface in a pattern similar to this.The large holes are first drilledwith regular bits and thenreamed with a three inch

(76mm) reamer bit. The reamed holes arenot charged with explosives and not blasted.

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The driller is indicates where the center linemeets the horizontal line marked for drillingof the “knee” holes. Knee holes are usuallythe easiest holes to collar and usually drillfaster than others as the pusher leg is morein line with the drill and exerts more forwardforce on the drill towards the face. The firmpressure of the bit face against the rocktends to help it cut the rock faster.

The driller points to where the line markedfor drilling the “lifter” holes meets the centerline of the drift. You will notice in this picturethat there are dots painted on the rock facein the center of some of the squares.The dots indicate four “helper” holes that areusually to drilled in the center of each of thesquares around the square containing theburn cut.The helper holes have less “burden” thanthe holes drilled on the corners of thesquares and help the round to break better.

When the drill is not in use it should beleaned against the wall in an upright positionas shown. The drill should not be on thefloor of the drift where water or debris couldpossibly enter the air or water connectiontubes, the exhaust ports of the drill or chuckbushing at the front end. A drill placed inthis position is ready to have the air andwater hoses easily and properly connectedto the appropriate fittings on the drill.

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The driller is showing how the steel retainermoves up to allow a drill steel to be placedin the chuck and close over the collar toprevent the drill steel from escaping the drill.The retainer should be checked at thebeginning of each shift to be sure that it hasthe proper tension to work properly. Theinner side of the retainer is examined toinsure that matching face of the retainer hasnot been worn away by the collars of the drillrods to a state where the device no longerholds the collar of the steel in the chuck orcould cause damage to drill rods.

The driller is checking that the leg couplingis tight to the drill body so that there is no airleakage when the drill is in operation. Theswivel action of the drill on the leg presentsa possible hazard of pinching hands orfingers between the bottom of the drill andthe leg. The driller needs to remain vigilantnot to place his hands or fingers in harmsway between the drill and leg connection.

The driller’s hand is on the throttle controlhandle that controls the flow of air enteringthe drill to power the hammering of thepiston in the drill. This handle can be pulledfully back to introduce a full flow of air to thefront end for blowing out drill rods while inthe hole. The throttle handle should be leftin the neutral position and the feed controlhandle in the reverse position when the drillis not in use. Should someone turn on theair to the drill with the controls in the properpositions the drill will not begin to operateprematurely.

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A driller controls all operations of the drilland the leg from the backhead of thePHQ250 Jackleg drill. The schematic at theright shows positions of the operatingcontrols on the backhead. The throttlehandle controls the flow of air to the hammerinside the drill. The positions of the handlein hammer mode are steadied by a ratchetmechanism in the backhead. When thehandle is turned back to the extreme all theair flow to the drill is directed to the front endto flush out the drill hole. The feed controlhandle provides the air flow for thrust orretraction of the feed pusher leg.

The driller’s hand grips the feed control handwith his thumb hovering over the retractbutton located on the feed control handle.When the button is in the position indicatedthe leg retract feature is not in use.When the leg retract button is pushedcompressed air flows to the bottom of theleg piston forcing it to retract into the leg.

(The driller’s hand is shown without glovesfor purpose of clarity. Drillers must weargloves as part of their protective clothing.)

The retract feature is very useful to a minerduring drilling operations. When the legreaches the end of the extension travel withdistance remaining between the front of therock drill and the rock face the drill and legcan be repositioned without moving the drillset-up. The driller can retract the end of thefeed leg to a position closer to the drill byslowing the hammer and pushing the retractbutton. Once the leg retracts the mineradvances the throttle hammer to continuedrilling the remaining distance to take thefront end of the drill to the collar of the hole.

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Connecting the water hose to the drill is astraightforward process. The inside of thewater tube swivel and the end of the waterhose should be visually checked to be surethere is no debris inside. The hose usuallyhas a water control valve located near theconnection to the drill to enable the driller toturn the water on an off. The driller needs toreduce the water flow for slow collaring ofholes and return it to full flow once the bitand steel have entered the rock and thehammer is drilling at full force and this valveneeds to be close by.

Connections are standard NPT threadedhose fittings shown in the picture. The drilleruses his mine wrench to tighten the nutsecurely on the NPT thread on the waterstem so that there is no water leakage.A hose whip is not required for waterconnections as the water pressure is lowenough that flow would not whip the hosearound when the hose is disconnected.Alternate fitting are “Sure-Lock” quickconnect fittings that allow the driller toquickly connect or remove the hose.One must ensure the locking pin is in placewhen using sure-lock connections.

Before connecting the air supply hose crackthe valve at the end of the supply hose and“blow the hose” to remove any accumulatedcondensate water or debris that may haveentered the hose while disconnected. Blowthe main supply hose and connect it to theshort supply hose and blow that hose aswell. Blow hoses until any visible watervapour coming out of the end of the hosedisappears. Shut off the valve and connectthe lubricator and short hose.

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Pour a half of a cup (100ml) of rock drill oilor rock drill grease into the end of the shorthose where it connects to the drill. It oftentakes up to five minutes for the oil misted inthe lubricator to travel the twelve feet ofhose and reach the drill during normaloperations. This is long enough for the rockdrill to “go dry” and the lack of lubricationcould cause serious damage to the interiorparts of the rock drill within minutes. Thesmall amount of rock drill oil will providelubrication to the drill until the air misted oilarrives from the lubricator.

Connect the short air hose to the air bendswivel connection on the drill. The shorthose must be no longer than twelve feet(four meters) between the lubricator and theair connection to the drill. If the miner isusing NPT fittings he must tighten thethreads securely and use a hose whip toprevent the hose coming free. If the miner isusing quick-connect couplings he mustinsert safety pins between the connections.Should the pressurized air supply hosecome free from the drill during operation thewhipping of the hose caused by highpressure compressed air exiting the hosecould cause serious injury to the driller.

When drills are assembled in the shop theair connection nut is secured with a TabWasher. When a drill is returned to the workplace from the drill shop the operator shouldalways check the rock drill to make sure theAir Connection Nut is tight and that a TabWasher is in place to secure the nut.PHQ recommend the installation of a “hosewhip” between water and air connections.The hose whip prevents the air hose from“whipping” around should it come looseduring drilling operations.

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Before opening the air supply to the drill theminer must check the amount of lubricantremaining in the reservoir of the in-linelubricator. Insure the air supply to thelubricator is turned off and bleed off anyremaining air pressure in the line beforeopening the lubricator. For this purposePHQ recommends that an air valve beinstalled near the lubricator to make itconvenient for the miner to shut off the air.The lubricator should be installed no furtherthan twelve feet (four meters) from the drillfor most efficient use of the misting of the oilor grease from the lubricator.

It is critical to prevent dirt or debris fromentering the lubricator whenever it isopened. The miner should always use aclean rag to wipe away any dirt or debris onthe outside of the lubricator in the area ofthe filler plug before opening the lubricator.

The lubricator is brought to an uprightposition with the safety filler cap on top. Thelubricator cap is usually easily unscrewedwith the use of the side of the handle of themine wrench. Should the cap be tight theminer can loosen the cap by hammeringsideways on the square corners of the fillercap to get the threads started.

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The PHQ lubricator is equipped with a safetyfiller plug. The threads on the plug arestraight threads (not tapered) and will holdthe plug until it is fully unscrewed. The plughas a hole drilled from inside the cap in amanner that allows air to escape to theoutside before the thread is fully unscrewed.There will be a loud hiss of escaping air towarn the driller if the air line is still underpressure. Should the driller hear the hiss hemust re-tighten the cap and make sure theair valve is closed, then he needs to drain offany pressurized air before opening the fillerplug again.

Once open the lubricator is filled from asuitable portable lubricant container. PHQrecommends the use of Oil Safe containersfor the transport storage and handling oflubricants. Oil Safe containers have apouring spout with an excellent sealingclosure to keep the oil or grease cleaninside. Fill the lubricator so the level of theoil reaches the top of the adjustment postseen just inside the opening in the lubricator.PHQ recommends the use of EP100 rockdrill oil or Triple Zero (000) rock drill greaseas proper lubricants for operating PHQ250rock drills.

PHQ lubricators are shipped with the settingat the full flow rate position. The full flowposition is indicated in this picture. There isa slot in the top of the adjustment post andwhen that slot is in line with air flow throughthe lubricator the maximum amount oflubricant is delivered into the air stream.With the setting in this position the oil in thelubricator will usually empty after four hoursdrilling in ambient temperatures between 10ºto 20º C. The lubricator should be set to fullflow setting when the ambient temperatureis below 5º C.

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The setting post can be turned with the useof the end of a metal hose clamp or screwdriver. Turning the post to an angle at 45º tothe air stream will reduce the flow of oil byapproximately 50% when drilling in ambienttemperatures between 10º to 20º C. At thissetting the lubricator will usually empty aftersix hours of drilling. The lubricator shouldbe set at this level for drilling in ambienttemperatures above 25º C

The adjustment post can be turned to aposition with the slot at an angle of 90º tothe air stream. In this position the flow of oilis at the lowest setting (nearly off) and thelubricator will empty of oil or grease usuallyafter eight hours of drilling in ambienttemperatures between 10º to 20º C. Thissetting should be used when drilling inambient temperatures over 35º C.

PHQ recommends the use of Vultrex TripleZero EP000 Rock Drill Grease as thelubricant of choice for PHQ250 Rock Drills.Vultrex grease was designed to for airmisting in the PHQ football style lubricatorand PHQ F61 Large Capacity LubricatorPHQ also recommends that the your choiceof rock drill grease or rock drill oil be stored,carried and dispensed from Oil Safecontainers. The Oil Safe containers aredesigned specifically to keep oil clean andfree from contaminants in the most hostile ofenvironments yet are fabricated from lightweight durable plastic materials.

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The driller prepares to lift and carry theassembled rock drill complete with hoses.The drill and leg weigh approximately 100lbs (45kg) however the hoses add weighand drag when the drill is transported. Thecorrect way to carry an assembled drill in thework place is to place the drill and leg in avertical position and lift the drill with yourshoulder placed under the backhead of thedrill. The driller has his drill in the rightconfiguration and is indicating the area ofthe drill that will be placed on his shoulder.

Make sure the area of travel is free fromobstructions before lifting the drill. The drilleris indicating the shoulder where he will placethe backhead of the drill. A right handeddriller will carry the drill on his right shoulderas he will be using his right hand to lift andsteady the drill. This leavess his left handfree to steady the drill while he carries it. Hecan also use his left hand to move the hosesshould they get caught or to move anythingthat is in the way of placing the drill where itwill be used

The driller is indicating the handle on the legwhich will be used to help carry the drill onceit has been lifted to his shoulder. The drilleris checking the hoses to be sure they arenot caught on anything thing that may hinderhim in carrying the drill and to be sure thatthe hoses will follow along behind while he iscarrying the drill.

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The miner prepares to lift the drill standing toone side of the drill leaning against the wall.He grips the control handle with his righthand and places his left hand under the drillin an area away from the pinch swivel point.

The left hand is placed under the feel pusherleg cylinder, the right firmly grips the controlhandle and pulls downwards to keep the drillin line with the feed pusher leg. The drill islifted into the upright position by steppingback and away pulling the drill upright in onemotion. Note that the miner keeps bothhands away from the “pinch point” areawhere the leg swivels on the drill whilelifting. Should the drill fall forward for anyreason his hands are out of the way.

The miner crouches slightly and places thebackhead of the drill on his right shoulderbringing his right hand around to grip thehandle of the feed pusher leg. The left handgrips the feed cylinder just above the feedleg handle to keep the drill from rotating inhis grasp. The drill weighs approximately 77pounds and should it fall to one side it wouldthrow the miner off balance and may causehim to fall with the drill. It is important forhim to support the weight of the drill on hisshoulder.

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The miner lifts the drill and leg straight upusing the straightening of his knees to takethe weight. The heavy drill should not belifted by using the muscles in one’s back.The hoses for the drill should now drapestraight down from the backhead of the drill.Care must be taken not to turn the bodywhile lifting drill from the floor and taking theweight of the drill onto the shoulder.

Once the drill is lifted into position andbalanced on the right shoulder the miner isfully upright with his left hand free and cancarry the drill with the right hand gripping thehandle on the feed pusher leg. Only afterthe drill has been lifted into position and thelegs are straight will the miner turn with theweight of the drill on his shoulder to walk towhere the drill will be used.

The miner carries the drill to the drill locationdragging the hoses and lubricator behindhim. It is good practice to examine the workplace to ensure nothing will hinder yourmovement while carrying the drill. Noticethe “drill ladder” placed in advance on thefloor of the drift in the proper location to takethe foot of the pusher leg. The “drill ladder”is fabricated by welding light weight tubingor pipe to form a ladder with rungs one footapart. The ladder has several short piecesof tubing welded at right angles to the tubingthat will grip in the loose rock on the floor ofthe drift.

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The miner places the foot of the pusher legon a rung of the “drill ladder” approximatelysix feet from the face of the drift. Thispositioning of the leg may need to beadjusted to allow the driller to collar holes inthe face with a four foot drill rod.

The driller stands to one side of the drill andlowers the drill to waist height towards theface of the drift. His right hand indicates thedirection that he will be drilling.

The driller positions the leg of the drill on thefront of his right thigh by extending his footout under the feed pusher leg. He allowsthe weight of the drill to come down on histhigh and controls the position of the front ofthe rock drill with his left hand. Again he iscareful not to get his hands near the pinchpoint at the joint of the feed pusher legswivel and the bottom of the rock drill. Hechecks that his hoses are free to move withthe operation of the drill.

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The driller demonstrates how his hands arefree with the drill and feed pusher leg inposition on his right leg just above the knee.The weight of the leg and a portion of theweight of the drill rests on the leg on thefloor. A large portion of the weight of thedrill is on the feed pusher leg that rests withthe prongs fixed in the drill ladder.

To insert a drill rod with into the chuck endof the drill the miner places the bit end of thedrill rod at the floor near the face. He opensthe steel retainer and tilts the drill forwardbringing the chuck over the collared end ofthe drill rod. Once the drill rod is in thechuck he closes the steel retainer holdingthe rod into the drill. The driller can nowallow the weight of the drill to rest on the drillrod and the feed pusher leg.

To re-position the drill to collar a hole on the“lifter” line. The driller brings his right legforward under the feed pusher leg to takethe weigh of the leg and drill, as he swivelsthe drill up lifting the steel and bit from thefloor. He adopts the right stance to collar adrill hole on the “lifter” hole line.

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The driller swivels the drill with a four footsteel and bit in the chuck into position andadopts the correct stance to collar a drillhole on the “breast hole” line. This picturedemonstrates the flexibility of movementavailable to the miner when he starts off byplacing his body in the right position tosupport and manipulate the drill and feedpusher leg.

The driller swivels the drill back down toposition the drill steel and bit to demonstratehow he would collar a drill hole at the “kneehole” line height.

The driller brings the drill back to a positionand adopts the right stance to collar a breasthole. Using the control handle he advancesthe feed pusher leg forward until the bitmakes contact with the rock face at theproper location. The driller carefully controlsthe pressure of the feed leg with the drill onpartial throttle to collar the hole. This allowsthe bit to slowly cut the irregular surface ofthe rock and produce a flat face. Once thebit has established a flat face the drillerincreases leg pressure and throttle hammermaking the bit cut faster. Drillers often startdrilling with a breast height hole as it is oneof the easier holes to drill.

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Once the drill bit has entered the rock a fewinches the hole is properly collared and thedriller gradually increases throttle to the fullhammering of the drill. Once the drill ishammering at full output the driller graduallyincreases the pressure of the leg using thecontrol handle until the machine achievesmaximum performance and penetration intothe rock face. At this point the driller “letsthe leg do the work”. The driller can relaxand control the drill simply by adjusting thefeed control handle until the full distance ofthe drill rod penetrates the rock.

Just before finishing the first hole drilled inthe drift round the driller checks to be surethe drill is receiving proper lubrication. Heshould observe if the drill collar at the frontend of the drill is wet with oil. Properlubrication produces a ring of wet oil wherethe collar meets the drill. He can also holdthe end of a miner’s wrench in the flow of airexhausting from the drill for a few minutes(about the time it takes to drill a four footsteel).

The end of the wrench should be wet with aresidue from the rock drill oil that is blowingthrough the drill and exiting at the exhaustport. This test should be repeated severaltimes during the drilling of the drift round.When no oil is seen on the wrench it is timeto refill the lubricator. Lack of properlubrication is the leading cause of failure ofrock drill parts. A good miner makes surethe drill is well lubricated or it could cost theloss of the entire shift if the drill breaks downand there is no spare drill at hand.

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Once the first breast hole is completed thedriller moves down to collar a “knee hole”.Note that he has not moved the position ofthe feed pusher leg from his thigh. Drillersusually drill all the holes (breast, knee, back,lifter) in order of difficulty on one line beforemoving the leg to the next line. This saves alot of work moving the drill, leg, drill ladderand pulling hoses from one location to thenext. Usually when collaring a hole thedriller will reduce the water flow to the bit toprevent water from spraying back at him.He needs just enough flow to control anydust generated from the bit cutting the rock.

The driller has noticed that the rock face isat an angle to the direction he wishes tocollar the knee hole, so he rests the drill biton the face and uses the pusher leg to raisethe drill so that the face of the bit is flat tothe rock face. In this position with the drillthrottle on partial hammer and just the weighof the drill resting on the bit he begins tocollar the hole. As the driller increases thethrottle hammer he needs to increase theflow of water to the drill bit to remove the drillcuttings from the hole as fast as possible.

Once the drill bit has created a one inchdeep indentation in the rock face the drillerlowers pressure on the pusher leg allowingthe weigh of the drill to drop down more inline with the direction required for the hole.He gradually increases the throttle hammeraccelerating the drilling and carefullycontrols the feed pressure to allow the drillto continue to align in the right position.

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Once the drill has reached alignment withthe direction of the drill hole the drillerincreases the throttle hammer to full on andthe feed pressure of the pusher leg toachieve maximum penetration of the bit intothe rock. With the bit approximately one footinto the hole the driller can relax and allowthe feed pusher leg to do the work. Hestands close to the drill and watches therotating drill rod carefully to insure properrotation and continually adjusts the feed legpressure to insure the drill does not stall.

When the drill is hammering and rotating atoptimum performance the driller can standback and watch the steel and bit penetratethe rock face. Drills have a reciprocatinghammer and generate harmful vibrations tooperator’s hands. The driller should keephis hands off the drill whenever possible andonly touch the drill when adjustment to thecontrols is required to optimize performance.Though relaxed the miner must continuouslyremain vigilant and monitor drill performanceto make adjustments to the feed.

The driller collars the first hole in the “burncut” after aligning the drill bit exactly on thetop spot painted on the rock face. It is veryimportant to collar and drill the holes in the“burn cut” exactly as measured out on theface. Note the two plastic loading sticksprotruding from the breast hole and kneehole next to the cut. The driller uses thesetwo loading stick to gauge the direction ofthe holes and to be sure the holes drilled inthe “burn cut” do not approach or intersectthe holes already drilled.

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Once the hole is collared and the rock drill isup to full throttle with proper feed pressurethe miner concentrates on keeping the drillaligned with the drill rod so that the holedrills as straight as possible. Usually thefirst two feet of drilling with the four foot steelemploys less feed pressure to ensure the bitand drill rod are not forcing out of alignment.The holes in the “burn cut” are very closetogether and it is important not to break onehole into another.

When the drill has reached two feet into therock face the driller opens up to full throttleand maximum feed pressure on the thrustleg to drill the hole at the best penetrationrate possible. The bit will not wandersignificantly once two feed of drill rod is inthe hole.

Once the hole is finished the miner preparesto retract the drill rod from the hole. Theminer shuts down the air to the throttle forthe hammer and the air powering the thrustof the feed leg. With the drill hanging on thedrill rod the miner moves back and lifts theend of the leg out of the drill ladder rung androtates the feed control handle pushing thethrust leg out to full extension length. Theend of the leg is dropped back onto a rungon the drill ladder.

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The miner opens the throttle valve with hisright hand to provide low hammer to the drill.He drops his right hand to grip the feedcontrol handle and pushes in the retractbutton. With his left hand pulling on theunder side of the front end of the drill hepulls the drill out of the rock face aided bythe retract action of the leg and low vibrationof the drill. The miner may need to lift onthe drill or wiggle the drill around to help theretraction of the drill rod and bit from thehole in the drift face.

As the bit exits from the hole the miner isalready planning to collar the second hole inthe “burn cut”. The leg has retracted toprovide the proper distance from the face toenable the driller to collar the second hole inthe cut.

The miner supports the weight of the drillwith his thigh under the feed pusher leg andholding the drill in two hands. He allows thebit to drop down the face until it rests on thesecond mark in the cut below and slightly tothe left of the hole just finished. He followsthe same routine of collaring the secondhole very carefully while staying on themark. The miner will drill a few inches intothe rock face to be sure the drill steel is wellsupported before stopping the drill.

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The miner slides a plastic loading stick intothe first hole drilled in the cut just above thepresent hole location. He will use this stickto provide a sight measurement to gaugethe direction of the second hole. The drilleragain drills the first few feet with slightlylower feed pressure to be sure the drill holestarts perfectly in line with the first hole. Hecarefully watches alignment with the plasticloading stick to be sure the second hole isparallel to the first. He continues on lowthrottle until the drill has penetrated at leasttwo feet into the rock face.

Once the drill has penetrated the first twofeed of the rock face the hole will not deviatesignificantly from this point so the drilleropens up the throttle and feed pressure todrill at maximum penetration. A good minerwill leave the plastic loading stick in placecheck alignment as the hole deepens. Theprocess is repeated until all six holes havebeen drilled to a depth of four feet in the cut.With the assurance that the crucial holes inthe cut are in good alignment the miner thengoes back and deepens all the holes to eightfeet. It is relatively simple to move the drillbit and rod from hole to hole.

Once all six holes are drilled to depth in theproper location in the “burn cut” it is time toream three of the holes to a larger diameterto provide the space for the rock to swellwhen the “burn cut” is blasted. The drillerexamines the face of his button reamer bit tobe sure all the carbides are intact beforebeginning. Note that he has left the drillhanging on the drill rod in one of the cutholes, instead of dropping it to the floor orleaning it against the wall. He does this tominimize the amount of lifting and movingdone during the work shift.

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The driller has checked the button reamingbit and is ready to start. Note the taperedbody of the bit fits the special reaming steeldesigned to take this bit. A portion of thereaming rod protrudes through the face ofthe reamer bit. The protrusion of the drill rodwill be placed in the small hole alreadydrilled and provides a guide to ensure thatthe larger bit perfectly follows the center lineof the previously drilled hole. The pilotprevents the reamed holes from “breakingin” to the smaller holes. The smallerdiameter holes parallel to the reamed holeswill be charged with explosives.

When reaming holes the rock drill can beoperated at maximum feed pressure and fullthrottle from the beginning of the hole to thebottom as the reaming steel pilot is followingthe previously drilled hole with no chance ofwandering. Note the small holes to the rightand left of the hole being reamed in thispicture. These smaller diamter holes will becharged with explosives.

The driller gets a chance to relax while he isreaming holes as the larger drill bit tends topenetrate a bit slower. It is not necessary totouch the drill during reaming operations asit is usually set on full feed and full throttle(hammer) drilling the full length of the hole.The driller must remain vigilant and watchthe flow of water carrying the cuttings fromthe hole. Should the water flow stop for anyreason the drill is shut down until the waterflow can be recovered otherwise the bit can“mud” (become blocked by cuttings) and jamin the face.

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Once the cut has been drilled and reamedthe driller moves on to drill the lifter holes.Here he is using the same method alreadydescribed to place a drill rod in the chuck ofthe drill. Note that he once again resumesthe proper stance with his thigh under theleg of the drill and the drill balanced in frontof his body.

Immediately after inserting the drill steel andbit in the chuck of the drill a lifter hole iscollared at a down angle using the weight ofthe drill without feed pressure to the leg.The hole is drilled right on the line markedfor lifter holes and where the vertical lineintersects the lifter line.

When the bit reaches one inch into the rockthe driller shuts the supply of air to thehammer and air supply to the feed pusherleg. Holding the drill control handle with hisleft hand he raises the end of the feed legout of the drill ladder. He turns the feedcontrol to extend the end of the feed leg afew feet down the ladder and exerts enoughpressure to take the weigh of the drill again.The drill remains at the same angle as whenthe hole was collared.

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The miner re-opens the throttle control valveto start up the hammer and adjusts the feedpressure to allow the drill to descend to theproper position to align with the direction ofthe lifter hole. While lowering the drill hewatches to be sure the hoses are notpinched under the drill in the process.

Once the drill reaches proper alignment thedriller opens up the throttle to full on andfeed pressure to maximize the penetrationrate of the drill bit. Note that the drill andfeed are now lying right on the drill ladder.

Once the drill is running full force the minercan release the controls and stand erect.He will often hold the air supply hose toprevent the drill from rotating around the drillsteel as can often happen if the bit meetswith some resistance in the hole. Note thatthe pusher leg is directly in line with thedirection of drilling. The in-line leg allows forfull pressure and hammer and will producethe fastest penetration of the bit into the rockthat will be observed in drilling the round.

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The miner should be vigilant to be sure thereis a continuous flow of water clearing rockcuttings from the drilling bit. It is oftendifficult to retract the drill rod from “lifterholes” as they are at floor level where waterand debris can enter the hole. Once thehole is competed and the front end of thedrill has reached the rock face the miner willusually stop the drill, place one foot over thedrill rod at the collar and blow the hole usingthe throttle control handle in full reverseposition sending full force blowing air to thefront end of the drill and the bit in the hole.

The final series of holes to drill in a driftround are the “back” holes and they are themost difficult as they are usually over sevenfeet above the floor level. The travel of thepiston in the pusher leg is not long enoughto provide a flat angle to the drill for properthrusting. To extend the length of the legPHQ provides a simple “leg extension”. Theleg extension is thirty inches long with thesame two prongs used on the feed pusherleg at the “down end” and a receptacle atthe “upper end” that accepts the stingerpoint on the bottom of the feed pusher leg.

The leg extension is only used when drillingholes above seven feet from the floor level.The miner indicates that he will be using thisleg extension to drill the five back holesacross the top of the drift round and ispointing at the “back hole” line painted onthe rock face of the drift.

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The driller retracts the pusher leg full in tothe base of the drill and moves the foot ofthe pusher leg on the drill ladder to withinfour feet of the drift rock face. With the drillwell balanced on his thigh he follows thesame method as before to place a four footsteel in the chuck of the drill in preparationto collaring the first back hole. He swivelsthe drill with the drill rod facing directlyupward. With the drill still on his thigh heturns the control handle for the thrust leg sothat the drill advances the bit end to the rockface.

The driller uses the leg to advance the drillup the face until it reaches the intersectionof a vertical line with the horizontal line forthe “back holes”. He starts collaring the holeon low hammer with the feed in the neutralposition until the bit has cut an indentation inthe rock face.

Once the bit has cut a slight indentation inthe rock face the driller increases the throttlefeed to the hammer and using the feed legcontrol handle advances the leg to lift thedrill up to an upright position bringing thedrill steel to drill in line with the properdirection for holes drilled in the drift round.

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Once the bit has penetrated six inches or sointo the rock face the driller shuts down thethrottle feed to the hammer and the air flowto the thrust leg so that the drill and feedhang on the drill rod protruding from thehole. He is preparing to re-position the legand add the leg extension.

With the drill shut down the driller lifts theend of the feed pusher leg and inserts theleg extension. The “upper end” of the legextension with the receptacle slides over thestinger point at the bottom of the feedpusher leg on the drill and the device formsa rigid thirty inch extension to the overalllength of the feed pusher leg.

The driller now resumes drilling the backhole bringing the drill up level so that thehole will be in proper alignment with the restof the holes in the drift round. “Back holes”are always drilled looking slightly upwardfrom horizontal as out of necessity they arecollared about six inches below the actualback of the drift. The upward angle bringsthe bottom of the hole high enough tomaintains the size of the drift at the properheight.

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It is very difficult for an operator to hold on tothe drill with his two arms fully extended.The driller will usually drop his arms andhands to hold on to the piston of the feed legto provide guidance to the drill and prevent iffrom moving from side to side in the earlystages of drilling a “back hole”.

The miner must remain vigilant at all timeskeeping an eye on the rotation of the drill rodand watching the flow of water clearingcuttings from the bit. With long experienceoperators become familiar with the sound ofa rock drill that is operating at full efficiency.A good operator will hear a change in thesound of the drill during operation and hecan often head off any trouble by grabbingthe controls when the sound changes. Mostof the time the driller can exert the propercontrol over the drill by adjusting the feedpressure.

Once the hole is drilled to full depth thedriller shuts down the throttle air supply tothe hammer and the feed to the pusher legto allow the drill to hang on the drill rodprotruding from the rock face. He lifts theend of the pusher leg and removes the legextension and sets it to one side.

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The miner positions himself to one sideunder the drill facing away from the rockface. With the drill hanging on the drill rodprotruding from the face he is able to pushthe drill away from the rock face moving thedrill rod out of the hole. If he meets a lot ofresistance retracting the drill rod he will turnthe throttle on low hammer to use vibrationof the drill to help him move it from the face.Working with the rock drill at high heightsmakes it difficult to drill “back holes” and toretract the drill rod and bit from the holesonce finished. The miner must stand erectand remain alert when handling a drill abovehis head.

The miner will often open the steel retainerand pull the rock drill off of the drill steel. Hecan then slip the hex hole in the end of hisminer’s wrench over the drill rod and pull itout of the hole. If he meets resistance hecan turn the drill rod using the wrench.A combination of turning the drill rod andpulling will extract drill steel most of the time.

Drilling near the wall can sometimes bedifficult for a driller as it may put him on the“wrong side” of the drill where he is not usedto operating. Good drillers will often collarall the holes near the wall from the samestance and same side of the drill where theynormally drill the second line of holes withthe end of the leg on the drill ladder where itwas set to drill the second line of holes threefeet away from the wall.

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Once all the holes are collared the driller willmove the drill ladder close to the wall in linewith the holes to be drilled at the side of thedrift.

The driller pushes the drill ladder as tight tothe wall as he can. He is now ready to finishdrilling the holes along the wall.

The end of the pusher leg is placed in a rungon the drill ladder and the bit introduced toone of the pre-collared holes. The drillerstands on his “wrong side” of the drill andleg and uses the control handle to adjust thepressure of the pusher leg on the drill as heaccelerates the air flow to the hammer withthe throttle control.

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One advantage of drilling near the wall isthat the drill can not fall over and away fromthe driller. The driller can often complete theholes with the minimum use of his hands tohold the drill. Again he must keep attentionto the rotation of the drill rod and the flow offlushing water coming from the drill holewhile listening to the rythym of the sound ofthe properly running drill. All the while hecontinually adjusts the controls to maximizethe penetration rate of the drill bit.

A typical drift heading design layout is shown. The miner will adjust the number of holes required toaffectively break the round to the bottom of the holes every time. Ground conditions often dictatethat more or less holes will be more effective however the pattern is basically the same every time.

14 holes of small diameter around theoutside edges of the round. Outside holesmay need to be collared inside the lines andare angled slightly outwards to compensate.6 holes of small diameter drilled at the

intersections of the lines inside the round11 holes of small diameter in the center ofhe squares formed by intersecting lines.6 holes of small diameter in the burn cut3 holes reamed from smaller to larger

diameter in the burn cut. The large holesare not charged with explosives or blasted.A total of 400 feet (120 meters) of drilling inan 10 foot (3 meter) drift round.

Blasting the holes in the right sequence is important to breaking the round properly. The miner usually useselectric timed caps to detonate holes in sequence radiating out from the “burn cut”. The three small cut holesare blasted first followed by the square of holes around the cut. It may be necessary to drill extra helper holesinside the square close to the cut holes if fragmentation of the rock is unsatisfactory and rounds fail to break.It is wise to start with “too many holes” rather than “not enough holes” to establish a proper drilling design.

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BEST OF CLASS PRACTICES FOR DRILLERS USING HAND HELD DRILLSMany of the troubles which arise from faulty operation can be eliminated or minimized if certain practices arefollowed in the care, handling and use of rock drills.

NEVER “ride the leg” or “hang on the drill control handle” when drilling. Skilled drillers learn thepusher leg does the work. Minor adjustment to the feed control optimizes drilling speed in the hole.

NEVER retract the steel from the drilled hole at full throttle. The piston inside the drill is meant tohammer under full load pressure from the pusher leg. Hammering without pressure damages parts.

NEVER strike the drill body with hard tools. A dent in the body of the drill will cause damage to theinside surface of the drill cylinder where tolerances are very close with the piston and cause scoring.

NEVER try to free a drill by manually turning the drill when locked on a stuck drill rod in the hole.The pawls can be broken when the drill is turned in the opposite direction to normal operating rotation.

NEVER open up the drill underground to attempt major repairs. The environment underground isusually wet and dirty and you may do more damage than good. Send the drill to the repair shop.

NEVER drag a drill along the ground as the exhaust ports, open end of the muffler, or other openingswill scoop up broken rock or dirty water which will cause malfunction of the drill and usually failure.

ALWAYS wear all personal protective equipment when working with rock drills. A miner must weara suitable hard hat with ear muffs, safety glasses, double ribbed hard toe boots, and suitable gloves.PHQ recommends the use of ear plugs as well as ear muffs to minimize the harmful effects of the noisegenerated by rock drills. Rock drills have been measured to emit as much as 110 decibels of noise.

ALWAYS blow any disconnected hoses before connecting to the lubricator or drill. Blowing the hosesremoves any condensate water or debris in the hose. Flush the water hose just to be on the safe side.

ALWAYS be sure the drill is getting adequate lubrication. Check the line oiler at the beginning ofevery shift to be sure it is full. Check the exhaust is misting oil and that the drill shank is wetted by oil.

ALWAYS keep the side rods at an equal tension and tightened over 90 ft lbs. Check the air connectionnut and the water connection nut occasionally while drilling to be sure they have not vibrated loose.

ALWAYS keep the drill aligned to the drill rod in the center of the hole. Collar the hole with a fourfoot steel to be close to the face and more in control of the drill. Collaring with long steel is difficult.

ALWAYS remove the drill to a safe distance from the holes to be blasted. If you disconnect the airand water hoses from the drill it is good practice to connect the air bend hose to the water bend hose.

ALWAYS store unused drills in an upright position out of the water and with all holes blocked withproper covers. Oily rags stuffed in the chuck and exhaust ports provide protection from airborne dust.

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MAXIMIZING DRILL PERFORMANCE WITH CARE AND USE OF DRILL STEEL AND BITSReliable performance of a rock drill depends to a large extent on the condition, care, handling and use of rockdrill bits. The driller should know the best practices to follow in the use of these tools.

NEVER pound on drill steel that is stuck in the hole. Nothing is accomplished and you may damagethe chuck insert, the chuck or the drill steel itself. A nick in a drill rod will cause a failure later on.

ALWAYS examine the collared end of a drill rod every time it is placed into the chuck of the drill.Drill steel should be stored shank end up against the wall. The striking face must be clean and freefrom damage when used in the drill. A steel shank can be blown clean by placing it in a drill exhaust.

NEVER approach the rock face with the drill running at full throttle. Always position the drill bitcarefully on the rock face and collar the hole at partial throttle to keep control of the drill. Start holeswith the bit face flat to the rock surface and adjust the position of the drill once a collar is established.

ALWAYS maintain maximum thrust of the pusher leg. Collaring at low pressure is usually maximumthat can be used without losing control. When drilling in the hole maximum thrust is at a level justbelow stalling of the drill. Maximum pressure on a bit yields the best bit life and drilling performance.

ALWAYS run the rock drill in alignment with the drill rod to minimize side pressure on the steel andwearing of the drill shank and chuck insert. Chuck inserts worn from side pressure produce a marked“coke bottle” shape on a drill shank, resulting in broken collars, chipped striking faces and lower life.

ALWAYS maintain a robust flow of water to the drill bit. A good driller keeps his eyes riveted on thewater coming out of the face as it tells him how the drill is performing. Stop the drill and blow thehole at the end of each drill steel run to facilitate retracting the drill rod and bit from the hole.

NEVER force a larger bit following a smaller bit in a hole. Even button bits that have been sharpenedcan vary in diameter. An experienced driller makes sure to always follow larger bits with a smaller bit.Never over-drill a bit to the extent the carbide inserts are flat and no other bit can follow it in the hole.

NEVER handle drill rods roughly or allow drill steel to drop to the floor. A small nick in the casehardened surface of a drill rod can lead to breakage of the rod while drilling. A break outside the holewill cause the drill to suddenly push forward and fall. This could be dangerous for the miner.

ALWAYS put aside any damaged drill rods for return to the shop. One drill rod with a damagedstriking face will damage the face of the piston in the drill. The damaged piston will in turn quicklydamage any new drill rods placed in the drill and can eventually cause all the drill rods to be ruined.