Fabrication tools, machines and equipment are vital assets across various sectors in Kenya, from county referral hospitals maintaining surgical instruments to retail businesses managing metal fixtures. Proper maintenance ensures these resources remain reliable, safe, and efficient, reducing downtime and operational costs. This chapter explores key practices in repairing fabrication tools and implementing preventive maintenance for fabrication machinery, enabling professionals to sustain productivity and extend equipment lifespan in diverse work environments.

4.1 Fabrication Tools Repair

Fabrication tools, whether hand tools or power tools, are subject to wear, damage, and malfunction from frequent use. Repairing these tools promptly and effectively is essential to maintain their functionality and ensure workplace safety. Example: in a welding and fabrication workshop, a worn pair of tinsnips or a cracked grinder disc left in service slows production and exposes the operator to injury, so skilled and timely repair keeps jobs on schedule.

Common faults in power tools

Power tools combine the mechanical parts discussed in this topic with motors, switches and wiring, so they develop faults of their own. Recognising these faults early allows a technician to decide whether the tool can be repaired on site or should be sent to a service centre. Example: in a fabrication workshop, a drill running hot and smelling of burning was found to have worn carbon brushes, which were replaced in minutes.

• Electrical failures: Wiring faults or motor burnout can stop tools such as grinders or drills from operating.
• Mechanical wear: Bearings, gears and brushes wear down, causing noise, vibration and loss of power.
• Overheating: Prolonged use without cooling leads to thermal damage of the windings and casing.
• Switch and trigger malfunction: Faulty controls prevent proper tool activation or fail to switch the tool off.
• Damaged cords and plugs: Frayed cables pose shock hazards and disrupt the power supply.

Repair tools and techniques

Effective repair requires appropriate tools and methods suited to the specific fault and tool type. Technicians in a fabrication workshop usually combine manual skills such as filing and fitting with specialised equipment such as a bench grinder and a multimeter.

Essential repair tools:

Repair techniques:

• Reassembling and tightening: Ensuring all fasteners are secure and moving parts are aligned.
• Wiring repair: Replacing damaged cables, soldering loose connections and testing continuity.
• Component replacement: Installing new springs, bearings or handles to restore full function.
• Straightening and realigning: Gently correcting slightly bent parts in a vice so that jaws, blades and shafts run true.
• Fabricating a part: Making a simple replacement such as a pin, wedge or bushing in the workshop when a bought part is not available.

Safety considerations during repairs

Repairing fabrication tools involves risks including cuts, electric shocks, flying particles and exposure to hazardous materials. Observing safety protocols protects both the technician and the users of the repaired tools.

• Use of personal protective equipment (PPE): Goggles, aprons and suitable footwear should be worn to prevent injuries. Gloves are used for handling sharp or rusty tools, but not at a rotating grinder wheel where they can be caught.
• Isolation of power sources: Disconnect power tools from electricity before commencing repairs.
• Proper ventilation: Repairs involving soldering or solvent use require well-ventilated areas to avoid inhalation of fumes.
• Use of correct tools: Employing appropriate repair tools reduces the risk of accidents and further damage.
• Inspection after repair: Testing tools under controlled conditions ensures safety and functionality before returning to service.

Record keeping and reporting repairs

Maintaining accurate records of tool repairs supports asset management and budget planning. A workshop that tracks the repair history of its tools can schedule replacements before a worn tool fails during a job.

• Tool identification: Record tool type, model and serial number if applicable.
• Nature of fault: Document specific defects and symptoms observed.
• Repair actions taken: Detail procedures, parts replaced and time spent.
• Technician information: Name and qualifications of personnel performing the repair.
• Date and next inspection: Schedule follow-up checks to monitor tool condition.

4.1.1 Handles

The handle is the part of a tool through which the operator applies force and keeps control. A cracked, loose or slippery handle makes the tool unpredictable: a hammer head can fly off, a file tang can pierce the palm, and a chisel can slip. Handles are therefore inspected first and repaired or replaced before a tool is allowed back into service. Example: a ball-peen hammer with a split ash handle is withdrawn from the workshop tool store as soon as the head is seen moving on the shaft, and the handle is replaced the same day.

Common handle faults

• Cracks and splits: Wooden handles crack along the grain after repeated shock or when struck by a missed blow. A cracked handle must be replaced, not taped.
• Loose heads: Shrinkage of the wood, or a missing or worn wedge, lets the head wobble on the handle. This is one of the most dangerous faults because the head can detach in use.
• Broken or detached handles: Handles snap near the head (the "eye") from overstriking or misuse, leaving a stub inside the eye.
• Damaged plastic or rubber grips: Grips on screwdrivers, pliers and snips crack, split or turn loose on the shank, reducing control and electrical insulation.
• Slippery surfaces: Oil, grease and sweat soak into wood and worn grips, making the tool hard to hold securely.
• Loose ferrules and tangs: On files and chisels the metal ring (ferrule) or the tang seat can loosen, so the handle turns or comes off under load.

Replacing a wooden hammer handle

1. Select the correct handle: Choose a straight-grained handle of the right length and a size that matches the weight of the head and the shape of the eye.
2. Secure the head: Clamp the head in a bench vice, using soft jaws or a wooden block so the face is not marked.
3. Remove the old handle: Saw off the broken shaft close to the head, then drill through the stub and drive out the remaining wood with a drift punch. Wear goggles throughout.
4. Clean the eye: Remove splinters and rust from the inside of the eye with a round file or emery cloth so the new handle seats fully.
5. Shape and fit the new handle: Dress the end of the handle with a rasp or file until it slides snugly into the eye, checking the head sits square to the handle.
6. Seat the head: Tap the handle end on a firm surface or strike it with a mallet until the head is fully seated.
7. Wedge the head: Saw a slot (kerf) across the top of the handle if one is not already cut, and drive a hardwood wedge into the slot. Add a metal wedge across it where the design requires.
8. Trim and finish: Cut off the protruding wood flush with the head, smooth the grip with sandpaper and test by tapping lightly on scrap before release.

4.1.2 Heads

The head is the working end of striking and driving tools such as hammers, chisels, punches, centre punches and screwdrivers. Constant impact deforms the metal, chips the faces and spreads the struck end into a mushroom shape. Mushroomed heads throw off sharp metal fragments, so heads must be dressed or replaced before they injure the operator or bystanders. Example: a site fabrication team reconditions its cold chisels at the start of each week to remove mushrooming before work begins.

Common head faults

• Mushrooming: The struck end of a chisel or punch spreads outwards into a ragged lip after repeated hammering. The lip can break off and fly out as a splinter.
• Chipped or cracked faces: Striking hardened surfaces, or using a hammer for a job it was not made for, chips the face. A cracked head cannot be safely repaired and must be scrapped.
• Deformation: Chisels and punches may bend or warp from misuse or impact, and hammer faces may be marked or dished, leaving the head out of true.
• Corrosion and rust: Exposure to moisture causes rust, weakening metal parts and pitting the face.
• Rounded or worn screwdriver tips: A tip that no longer matches the screw slot slips out and damages the fastener and the hand.
• Blunt or bent points: Punch and scriber points lose accuracy when worn or bent.

Dressing a mushroomed chisel head

1. Inspect and decide: Check the head for cracks. If it is cracked, discard it. If it is only mushroomed, it can be dressed.
2. Wear PPE: Put on safety goggles or a face shield and close-fitting overalls. Do not wear loose gloves at the grinder. Make sure the bench grinder guard and tool rest are correctly set.
3. Grind the lip away: Hold the chisel against the wheel and grind back the spread metal until the head is a clean, slightly rounded end.
4. Form a chamfer: Grind a small bevel around the head, so that future spreading is limited and no sharp lip forms.
5. Keep the metal cool: Dip the tool in water frequently. Overheating changes the hardness of the steel and ruins the temper.
6. Check the cutting end: Look at the edge at the other end and re-grind if needed (see 4.1.4 Blades).
7. Remove rust and burrs: Clean the shank with a wire brush or emery cloth and file off any sharp burrs before use.

4.1.3 Jaws

Jaws are the gripping or clamping parts of pliers, adjustable spanners, vices, locking grips, clamps and snips. They must close squarely and bite firmly. Worn serrations, misaligned faces or a loose pivot let the workpiece slip, and a slipping tool injures hands and damages the job. Example: the maintenance team of a fabrication workshop restored its slip-joint pliers by re-cutting the teeth and replacing the pivot rivet, rather than buying new sets.

Common jaw faults

• Worn or smooth serrations: The teeth flatten with use, so the jaws no longer grip round or flat stock.
• Misaligned jaws: Jaws that do not meet evenly, or cross over each other, grip only on one edge and slip.
• Joint and spring failures: Tools with moving parts like pliers, snips and locking grips may develop a loose or seized joint or a broken return spring, impairing function.
• Spread or sprung jaws: Adjustable spanners and pliers used as hammers or with extension pipes have jaws that open out and no longer hold a nut square.
• Damaged vice jaw plates: Cut, chipped or worn plates on a bench vice mark work and let it creep.
• Rust at the pivot: Corrosion at the joint hinders movement and makes the tool stiff to operate.

Repairing a pair of pliers

1. Clean the tool: Remove dirt, oil and rust with a wire brush and rust remover so the fault can be seen clearly.
2. Test the action: Open and close the jaws, noting stiffness, looseness, side play and where the jaws touch.
3. Adjust the pivot: If the joint is loose, tighten or re-peen the pivot rivet or bolt. If it is stiff, free it with penetrating oil and work it until smooth.
4. Correct alignment: Where jaws are slightly misaligned, a skilled technician can gently adjust them in a vice. Badly bent jaws mean the tool should be retired.
5. Re-cut the serrations: Use a small triangular file to restore the teeth, following the existing pattern.
6. Replace faulty springs: Fit a new spring of the correct type if the old one is broken or weak.
7. Test under load: Grip a piece of scrap rod and check that the jaws hold without slipping and release cleanly.

4.1.4 Blades

Blades are the cutting edges of shears, snips, chisels, hacksaws, knives and similar tools. Over time, blades on these tools become dull, reducing cutting efficiency and increasing operator effort, and a dull tool slips more readily than a sharp one. Sharpening restores the original edge angle; badly chipped, cracked or bent blades are replaced. Example: a fabrication workshop keeps a sharpening log for the shear blades on its sheet-metal bench so that edges are restored before the cut quality drops.

Common blade faults

• Dull cutting edges: The edge rounds over with use and needs more force to cut.
• Chipped or nicked edges: Cutting hard material or striking a nail or weld leaves notches that tear the cut.
• Bent or twisted blades: Overloading shears or snips, or twisting a hacksaw blade, produces a blade that no longer cuts straight.
• Loose blade pivots: Shear and snip blades that have play between them chew rather than cut the sheet.
• Corrosion: Rust on the blade face or edge roughens the cut and hinders movement.
• Broken or missing teeth: Hacksaw and saw blades with missing teeth cut slowly and wander off the line.

Sharpening a blade

1. Secure the tool: Hold the blade firmly in a vice or on a rest so it cannot move.
2. Identify the original angle: Study the existing bevel. For example, a cold chisel for general mild steel work has an included angle of about 60°. Keep the original angle rather than creating a new one.
3. File or grind: Use a file or a grinding wheel to remove metal evenly along the bevel, always working from the same direction.
4. Control heat: When grinding, dip the blade in water often. Blue or straw-coloured steel shows that the edge has overheated and softened.
5. Remove the burr: Stone or lightly file the back of the edge to remove the thin wire burr left by sharpening.
6. Check the edge: Test on scrap material of the type the tool normally cuts. A good edge cuts cleanly with moderate force.
7. Protect the blade: Wipe the blade clean and apply a thin layer of oil to keep the edge from rusting in storage.

4.1.5 Discs and wheels

Discs and wheels include grinding wheels, cutting-off discs, flap discs and wire wheels used on bench grinders and angle grinders. They rotate at very high speed, so any damage can cause them to shatter and throw fragments. Most abrasive cutting discs cannot be repaired and are replaced when worn or damaged, while grinding wheels can be dressed to restore their shape and cutting action. Example: a fabrication workshop replaced the cutting disc on its angle grinder after a chip was noticed on the rim, instead of finishing the pipe cutting job.

Common disc and wheel faults

• Cracks and chips: Damage from dropping, side loading or impact. A cracked disc or wheel is never used.
• Glazing: The abrasive grains become smooth and clogged, so the wheel burns rather than cuts the metal.
• Loading: Metal particles, especially from soft metals, fill the wheel surface and reduce its cutting action.
• Out-of-round or uneven wear: The wheel runs with vibration, which damages bearings and makes accurate work impossible.
• Worn diameter: A disc worn too small loses surface speed and may not fit the guard properly.
• Wrong disc for the tool: A disc whose maximum speed rating is below the speed of the machine can burst. The label on the disc and the machine must be checked before fitting.

Dressing a grinding wheel

1. Disconnect and inspect: Isolate the grinder from power and examine the wheel for cracks. For a vitrified wheel, suspend it and tap it gently with a non-metallic object. A clear ringing sound suggests it is sound, while a dull sound suggests a crack.
2. Set the guard and rest: Fit the guard and set the tool rest close to the wheel, with a small gap as given in the machine instructions.
3. Put on PPE: Wear goggles, a face shield, hearing protection and dust protection.
4. Run the grinder up to speed: Stand to the side, not in line with the wheel, and let it reach full speed.
5. Apply the dresser: Hold a wheel dresser on the rest and move it lightly across the face of the wheel to remove the glazed or loaded layer and restore a true, flat face.
6. Check the result: The wheel should now run smoothly and cut freely. Stop the machine and check the remaining wheel thickness.
7. Replace if worn: If the wheel is too small, cracked or cannot be trued, replace it with one of the correct size and speed rating.

Replacing a disc on an angle grinder

1. Isolate the power: Switch off and unplug the grinder.
2. Lock the spindle: Press the spindle lock button and loosen the flange nut with the correct key spanner.
3. Remove the old disc: Take off the nut, outer flange and disc, and clean the flanges so they are free of dust and burrs.
4. Check the new disc: Confirm the size, bore and maximum speed rating suit the machine, and look for cracks or damage.
5. Fit the new disc: Place the disc on the inner flange, refit the outer flange and tighten the nut firmly with the key.
6. Refit the guard: Check the guard is in position and covers the side facing the operator.
7. Test run: Hold the grinder away from people and run it idle for about a minute before use, listening for vibration or noise.

Chapter Summary

This chapter focused on the essential practices for maintaining fabrication tools, machines, and equipment to ensure their longevity and optimal performance. The repair of fabrication tools was examined in detail, covering critical components such as handles, heads, jaws, blades, and discs or wheels, highlighting the importance of addressing wear and damage promptly. Preventive maintenance of fabrication machines was emphasized, beginning with the cleaning of external surfaces to remove dust and debris that could impair operation. Careful inspection of cables, connectors, and power sources was discussed as a vital step to prevent electrical faults and ensure safety. Lubrication of moving parts was presented as a necessary routine to reduce friction and wear, thereby enhancing machine efficiency. The integration of these maintenance activities supports uninterrupted fabrication processes and safeguards investment in equipment. Overall, the chapter provided a comprehensive approach to preserving the functionality and safety of fabrication tools and machinery.