Doc #45 — Chainsaw and Tool Maintenance

---

RECOMMENDED ACTIONS (BY URGENCY)

First month:

1. Include chainsaws, chains, bars, files, sprockets, and two-stroke oil in the national asset census (Doc #8). Count by type and condition — professional saws separately from consumer models.
2. Issue chainsaw maintenance guidance to all chainsaw owners — emphasise sharpening discipline and proper storage. A one-page laminated field card would serve.
3. Classify professional chainsaw mechanics and saw service technicians as critical-skills personnel.
4. Requisition wholesale stocks of chainsaw chains, guide bars, round files, flat files, sprockets, spark plugs, and two-stroke oil from distributors and retailers (Category A, Doc #1).

First 3 months:

5. Establish chainsaw maintenance training at regional forestry centres. Target: every professional chainsaw operator competent in field sharpening, bar maintenance, and basic engine service. Every operator already sharps their own chain — the goal is to ensure all of them do it correctly and frequently.
6. Begin testing tallow and plant oil substitutes for bar and chain oil (Doc #34). Evaluate wear rates under different lubricants and publish findings.
7. Inventory all crosscut saws, bow saws, and felling axes in NZ — many are in museums, private collections, farm sheds, and Men’s Sheds. Assess condition and identify which can be returned to service.
8. Identify and contact all surviving practitioners with crosscut sawing experience. Begin heritage skills documentation and training (Doc #160).

First year:

9. Begin rationing chainsaw consumables — allocate chains, bars, and files on the basis of forestry priority, not commercial availability.
10. Establish regional chainsaw file reconditioning capability — diamond honing of worn files to extend their useful life. This requires locating existing diamond honing tools and flat diamond plates (held by saw shops, engineering suppliers, and hobbyist woodworkers) and concentrating them at regional centres with trained operators.
11. Commission crosscut saw restoration and sharpening workshops. A sharp crosscut saw is a productive tool; a dull one is almost useless.
12. Begin training crosscut sawing crews at regional forestry operations — not to replace chainsaws yet, but to build the workforce that will be needed when chainsaw consumables run out.
13. Trial electric chainsaw deployment near grid-connected forest operations.

Years 2–5:

14. Transition progressively to manual methods for limbing, bucking, and small-tree work. Reserve petrol chainsaws for large-tree felling where the productivity gap is largest.
15. Develop NZ-manufactured crosscut saws from Glenbrook steel (Doc #89), heat-treated and sharpened by trained saw doctors.
16. Develop NZ-manufactured chainsaw chain — this is significantly harder than crosscut saws (see Section 7) but extends the chainsaw era if achieved.
17. Expand electric chainsaw fleet as battery and mains-powered units prove viable near grid infrastructure.

---

ECONOMIC JUSTIFICATION

The productivity gap between chainsaw and manual methods

The economic case for extending chainsaw operational life is straightforward: chainsaws are roughly 5–10 times more productive than the manual alternative for felling, and the performance gap is larger for big trees.⁴⁵

Task	Chainsaw (1 operator)	Crosscut saw (2-person crew)	Productivity ratio
Fell a 40 cm radiata pine	1–2 minutes	15–30 minutes	~10:1
Fell a 60 cm radiata pine	3–5 minutes	30–60 minutes	~10:1
Fell a 80 cm radiata pine	5–10 minutes	45–120 minutes	~8:1
Buck (cross-cut) a 40 cm log	30–60 seconds	5–10 minutes	~8:1
Limb a medium tree	5–10 minutes	20–40 minutes	~4:1

These are approximate ranges based on professional logging experience and historical crosscut sawing records. Actual times vary with tree species, condition, terrain, operator skill, and tool sharpness.⁶⁷

Labour cost of premature chainsaw loss: If NZ’s forestry sector transitions to manual methods 5 years earlier than necessary due to poor maintenance and consumable waste, the additional labour cost is substantial. Assuming NZ requires approximately 500,000–1,000,000 cubic metres of harvested timber per year under recovery conditions (Doc #99), and the productivity gap between chainsaw and crosscut for the felling component is roughly 5:1, premature transition to manual methods requires approximately 200–500 additional forestry workers dedicated to felling alone. Over 5 years, this represents 1,000–2,500 person-years of additional labour diverted from other recovery tasks. A mitigating factor: the manual forestry labour is general physical labour that can be staffed from the available workforce (people who are underemployed anyway under recovery conditions), while the chainsaw maintenance and training programme that extends chainsaw life requires skilled technicians and saw doctors — a much scarcer pool. The saved person-years are real but “cheaper” than the specialist time needed to achieve the savings.

Cost of the maintenance and training programme

Component	Person-years (Year 1)	Ongoing (per year)
Chainsaw maintenance training (regional courses)	5–10	2–5
Crosscut saw restoration and sharpening	3–5	2–3
Crosscut sawing training programme	5–10	10–20
Consumable inventory and distribution management	2–3	1–2
Electric chainsaw adaptation programme	2–3	1–2
Total	~17–31	~16–32

The investment is modest relative to the labour savings from extending chainsaw operational life. Even one additional year of effective chainsaw use across NZ’s forestry sector saves 200–500 person-years of manual labour.

---

1. CHAINSAW ANATOMY AND FAILURE MODES

1.1 Key components

A chainsaw consists of:

• Engine: Two-stroke petrol engine, typically 30–120 cc depending on saw size. Professional felling saws (Stihl MS 462, Husqvarna 572 XP) are 70–80 cc. Farm and arborist saws are 30–55 cc. The engine drives a centrifugal clutch that engages the chain drive when the throttle is applied.⁸
• Guide bar: A flat steel rail around which the chain travels. Bars range from 30 cm (light pruning) to 90+ cm (large-tree felling). The bar has a groove (rail) that guides the chain, and a sprocket at the nose that reduces friction.
• Chain: A loop of linked steel components — drive links (engage the bar groove and the drive sprocket), tie straps (connect the links), and cutting teeth (chrome-plated or chrome-hardened steel with a specific rake angle and depth gauge setting).
• Drive sprocket: Connects the clutch to the chain. Available as spur (integral with the clutch drum) or rim (replaceable ring on a splined hub). Rim sprockets are preferred because the worn sprocket can be replaced without replacing the entire clutch drum.⁹
• Air filter, fuel filter, spark plug: Standard small-engine consumables. Air filter condition directly affects engine life.

1.2 What wears out first

In approximate order of depletion under normal professional use:

1. Chain cutting teeth — ground away by repeated sharpening, each sharpening removing approximately 0.2–0.3 mm of cutter length. A new cutter is approximately 8–9 mm long; minimum usable length is approximately 3–4 mm depending on chain type. This gives roughly 5–10 sharpenings per cutter before the chain must be retired.¹⁰
2. Round files — the tool used to sharpen chains. A single round file can sharpen 3–8 chains before losing its cutting ability, depending on technique and file quality.¹¹
3. Drive sprocket — wears where the chain drive links engage. A sprocket lasts approximately 2–3 chains. Operating a new chain on a worn sprocket accelerates chain wear.
4. Guide bar rails — wear where the chain slides. Periodic turning (flipping the bar 180 degrees) equalises wear. A bar lasts approximately 3–5 chains with proper maintenance.¹²
5. Bar nose sprocket — the roller bearing at the bar tip. Requires periodic greasing. Failure causes increased friction, chain derailment, and bar damage.
6. Spark plug — typically replaced every 100–200 hours. Can be cleaned and re-gapped many times before replacement is necessary.
7. Air filter — cleanable, but eventually the filter medium degrades.
8. Engine internals (piston, cylinder, bearings, crankshaft seals) — the last things to fail on a properly maintained saw. Professional saws can achieve 1,500–2,000+ hours before major engine overhaul.¹³

The implication: Chainsaw bodies last far longer than their consumables. The bottleneck is the chain-file-sprocket-bar consumable loop, not the engine. Every effort to extend consumable life directly extends chainsaw operational life.

---

2. CHAIN SHARPENING — THE MOST IMPORTANT SKILL

2.1 Why sharpening matters

A sharp chain cuts efficiently, producing large chips, with minimal pressure from the operator. A dull chain produces dust instead of chips, requires the operator to force the saw into the wood, overheats the bar and chain, dramatically increases fuel consumption, and accelerates wear on every component. Operating a dull chain is the single most destructive thing an operator can do to a chainsaw.¹⁴

The difference between sharp and dull is not subtle. A sharp chain on a 70 cc saw drops a 40 cm radiata pine in under a minute with the saw’s own weight doing much of the work. The same saw with a dull chain takes several minutes of hard pushing, overheats, and comes out of the cut with a hot bar and a shortened chain life.

2.2 Sharpening technique

Chain sharpening requires:

• A round file of the correct diameter. Chain pitch determines file size: 3/8” pitch (the most common professional size) requires a 5.2 mm file; .325” pitch requires a 4.8 mm file; 3/8” low-profile requires a 4.0 mm file. Using the wrong file size produces incorrect cutter geometry.¹⁵
• A file guide or holder. Maintains the correct filing angle (typically 25–30 degrees from the bar centreline) and the correct file height relative to the cutter top plate. Freehand filing is possible with experience but produces less consistent results.
• A flat file for adjusting depth gauges (rakers). The depth gauge controls how deeply each cutter bites into the wood. As cutters are shortened by sharpening, depth gauges must be lowered to maintain cutting efficiency.
• A depth gauge tool (a flat metal template placed over the chain that sets the correct depth gauge height — typically 0.5–0.65 mm below the cutter depending on chain type and intended use).

The sharpening procedure:

1. Secure the saw with the bar in a vice or stump clamp, chain brake off, chain tension correct.
2. Identify the shortest cutter — this determines the filing target for all cutters (all cutters should be the same length for even cutting).
3. Starting from the shortest cutter, file each cutter on one side of the chain using the round file in the guide. File from inside to outside, lifting on the return stroke. Two to three strokes per cutter is typical for routine touch-up; five to eight for a moderately dull chain.
4. Count strokes — apply the same number to each cutter.
5. Reverse the saw and sharpen the cutters on the opposite side.
6. Check and adjust depth gauges with the flat file and depth gauge tool.
7. Release the chain brake, run the engine briefly, and test-cut.

Sharpening frequency: Professional loggers sharpen after every 2–3 fuel tank fillings, or whenever the saw stops producing chips. Under recovery conditions, the guideline should be: sharpen at every refuelling stop. Over-sharpening wastes file and cutter material; under-sharpening wastes everything else.¹⁶

2.3 Common sharpening errors

• Inconsistent cutter length: Causes the chain to cut in a curve. The longer cutters do more work and wear faster, creating a self-reinforcing asymmetry.
• Incorrect file angle: Too steep an angle produces a fragile edge that dulls quickly. Too shallow an angle produces a cutter that scrapes rather than bites.
• Neglecting depth gauges: As cutters are shortened, the depth gauge must be lowered or the chain will not feed into the cut. Operators who sharpen cutters but forget the rakers end up with a chain that looks sharp but will not cut.
• Filing with a worn file: A dull file glazes the chrome surface of the cutter rather than cutting it, producing a polished but not sharp edge. Files must be replaced when they lose their bite. Tactile feedback — the file should grab the cutter steel, not slide across it — is the test.

2.4 Maximising file life

Files are the binding constraint on chain sharpening. Under normal conditions, files are cheap and disposable. Under recovery conditions, they are a finite, irreplaceable resource.

Techniques to extend file life:

• File quality matters. Allocate the highest-quality files (Oregon, Stihl, Husqvarna branded) to professional users, not to intermittent operators who may waste them on poor technique.
• Use a file guide consistently. Freehand filing is harder on files because the inconsistent angle causes uneven loading.
• Clean the chain before sharpening. Dirt, resin, and grit on the cutters abrade the file.
• Lift on the return stroke. Dragging the file backward dulls it.
• Rotate the file periodically. Round files have cutting edges around their full circumference. Rotating the file 60 degrees in the holder every few sharpenings presents a fresh cutting surface.
• Store files dry, with edge protection. Moisture corrodes the hardened surface.

When files are exhausted: Diamond chainsaw sharpeners (rotary grinder wheels or flat diamond files) last far longer than steel files — effectively indefinitely for the volumes involved in chainsaw sharpening. NZ has some diamond sharpening tools in stock. If these can be identified and distributed to professional forestry users, they extend the sharpening capability well beyond the steel file supply.¹⁷

Electric bench grinders with thin grinding wheels can sharpen chainsaw chains very effectively and waste less file material than hand filing. These require electricity and a suitable grinding wheel, but for fixed base operations (mill sites, depots) they are more efficient than hand filing and should be used where available.

---

3. GUIDE BAR MAINTENANCE

3.1 Bar wear and its consequences

The guide bar is a precision-ground steel rail. The chain rides in a groove approximately 1.3–1.6 mm wide (depending on chain gauge). As the chain circulates, it wears the groove walls and the bar rails. Wear is accelerated by dirt ingestion, insufficient lubrication, chain tension problems, and operating with a dull chain.

Symptoms of bar wear: - The chain leans to one side in the cut (uneven rail wear) - The chain comes loose despite correct tension (groove walls worn) - Burrs develop on the bar rails (metal displaced by wear) - The bar heats excessively (increased friction from distorted groove)

3.2 Bar maintenance procedures

Daily: - Clean the bar groove with a groove-cleaning tool or a thin piece of sheet metal, removing packed sawdust, resin, and dirt - Check and clean the bar oil delivery holes (small holes at the bar mount area through which the oiler delivers lubrication) - Inspect bar rails for burrs; dress with a flat file if present - Check bar nose sprocket for free rotation; lubricate through the grease hole if equipped

Every chain change: - Flip the bar (turn it 180 degrees, top to bottom). This equalises rail wear, as most cutting loads are on the underside of the bar. - Measure the groove width with a gauge or by checking chain fit. If the chain has excessive side play, the groove is worn. - Check bar straightness — sight along the bar from the tip. A bent bar causes crooked cuts and accelerated chain wear.

Bar reconditioning: When bar rails develop uneven wear, they can be trued by grinding the bar flat on a surface grinder or by careful hand-filing. This requires a flat file, a straight edge, and patience. Professional saw shops use dedicated bar dressing tools. Under recovery conditions, a machinist with a surface grinder can recondition bars that would otherwise be discarded.¹⁸

3.3 Bar oil substitution

The bar oil system delivers lubricant to the chain as it runs around the bar. Modern chainsaws use automatic oilers that pump oil from a reservoir. The standard lubricant is purpose-made bar and chain oil — a petroleum-based tacky oil designed to resist fling-off at high chain speeds.

Substitutes (ranked by suitability):

1. Used motor oil (if any remains in stock): Adequate but thin. Flings off more than purpose-made bar oil. Better than nothing.
2. Tallow (rendered animal fat): Functions as a bar lubricant in warm conditions. In cold weather, tallow thickens excessively and may block the automatic oiler. In warm NZ conditions (Northland, Waikato, Bay of Plenty), tallow is serviceable. In colder regions (Southland, high country), it may need to be thinned with a lighter oil or applied manually.¹⁹
3. Canola oil: Good lubrication properties, widely available in NZ from domestic production. Adequate as a bar oil substitute. May gum up if left in the oiler for extended periods.
4. Lanolin (from wool scouring): Excellent lubricant, naturally tacky. Higher viscosity than petroleum bar oil. May be too thick for automatic oilers in some models but works well for manual application. NZ produces lanolin in significant quantities.²⁰

Performance gap: All substitutes are inferior to purpose-made bar oil. Chain and bar wear will increase by an estimated 20–50% depending on the substitute, cutting conditions, and application method. This is an acceptable trade-off when petroleum bar oil is unavailable — increased wear is preferable to operating without lubrication, which destroys bars and chains rapidly.

---

4. ENGINE MAINTENANCE AND FUEL

4.1 Two-stroke engine care

Chainsaw engines are small, air-cooled, two-stroke motors running at very high speeds (12,000–14,000 RPM at maximum). They are robust but intolerant of neglect. The key maintenance priorities:

Air filter: The single most important engine maintenance item. A chainsaw operates in a cloud of fine sawdust, and the air filter is all that prevents that dust from entering the cylinder and scoring the piston and bore. A clogged filter starves the engine of air, causing it to run rich (excess fuel), foul the spark plug, and lose power. A damaged or missing filter allows unfiltered air in, destroying the engine within hours.

• Clean the air filter after every day’s use. Most modern filters are foam, felt, or mesh types that can be cleaned by tapping, brushing, or washing in warm soapy water (tallow-based soap is fine).
• Inspect for tears or holes. A filter with even a small tear should be repaired or replaced — seal the tear with silicone if available, or replace the filter from stock.
• Fabricating replacement air filters: Foam filters can be cut from compatible open-cell foam. Mesh-type filters can be fabricated from fine woven metal screen. Neither matches the filtration efficiency of the original (improvised filters pass more fine dust, accelerating cylinder wear and shortening engine life), but both are far better than operating without a filter, which can destroy an engine within hours.

Fuel mix: Two-stroke chainsaws require pre-mixed fuel — petrol combined with two-stroke oil at a ratio of 40:1 to 50:1 (20–25 ml of oil per litre of petrol).²¹ The oil lubricates the piston and crankshaft bearings. Running without oil destroys the engine within minutes from bearing seizure.

• Two-stroke oil substitution: As petroleum two-stroke oil depletes, castor oil is a proven substitute. Castor oil was the standard two-stroke lubricant before synthetic oils and remains effective. It runs slightly dirtier (more carbon deposits) and requires more frequent spark plug cleaning, but it protects the engine adequately. Castor oil can be pressed from castor beans (Ricinus communis), which grow in NZ’s warmer regions and could be cultivated specifically for this purpose — though establishing a reliable supply requires planting, a growing season, harvest, and mechanical or hand pressing (Doc #34).²²
• Fuel: the hard constraint. Chainsaw engines run on petrol. There is no practical substitute that works in unmodified chainsaw carburettors. Ethanol blends above 10% cause carburetor swelling and fuel system damage in most chainsaw engines. Wood gas cannot be used (too low in energy density for the small, high-RPM engine). When petrol runs out, petrol chainsaws stop. This is not a maintenance problem — it is a fuel supply problem addressed in Doc #53.

Spark plugs: Clean carbon deposits from the electrode with a wire brush or fine abrasive after every 20–50 hours of operation. Regap the electrode to the manufacturer’s specification (typically 0.5–0.6 mm, depending on model) when the gap widens. A spark plug can be cleaned and reused many times before the electrode erodes to unusability. NZ stocks of small-engine spark plugs (NGK, Champion) are likely sufficient for many years given the relatively slow wear rate.²³

Fuel and air intake cleaning: Periodically clean the carburetor air intake screen and inspect the fuel filter (a small screen inside the fuel tank, attached to the fuel line). Clogged fuel filters restrict fuel flow and cause lean running, which overheats the piston. Replacement fuel filter screens can be fabricated from fine mesh if originals fail.

4.2 Storage and preservation

Chainsaws that are not in active use should be stored properly to preserve them:

• Drain fuel or add stabilizer. Petrol left in the tank and carburetor goes stale within months, forming varnish that clogs jets and passages. If fuel stabilizer (e.g., Sta-Bil) is available, add it per directions. Otherwise, drain the tank and run the engine until it stops to clear the carburetor.
• Remove the chain and bar. Clean the bar groove, oil the bar and chain, and store them wrapped in oiled cloth.
• Clean the air filter. Store it dry and clean.
• Remove the spark plug and add a few drops of two-stroke oil into the cylinder. Pull the starter cord slowly a few times to distribute the oil, then replace the plug. This prevents cylinder corrosion during storage.
• Store in a dry, covered location. Moisture causes internal corrosion. A garage or shed is adequate.

A chainsaw stored in this manner should remain serviceable for many years.

---

5. ELECTRIC CHAINSAWS — THE GRID-ADJACENT OPTION

NZ’s renewable grid (Doc #67, Doc #65) provides an energy source for electric chainsaws that does not deplete. Shifting to electric does not solve the chain and bar consumable problem, but it eliminates the fuel constraint for operations near grid infrastructure. Given that NZ’s plantation forests are concentrated in regions with grid access (Central North Island, Nelson-Marlborough, Canterbury),²⁴ a meaningful proportion of forestry work could be conducted within reach of the grid.

Corded electric chainsaws eliminate the fuel dependency entirely. They are limited by cord range (practically 50–100 metres from an outlet) and lower power output (approximately 2.0–2.5 kW — equivalent to a 35–45 cc petrol saw). Unsuitable for remote bush work, but well-suited for sawmill log yards, road-adjacent woodlots, community firewood processing, and arborist work in settled areas. NZ has an unknown but likely substantial number in private ownership. Their maintenance advantage is significant: no air filter, spark plug, fuel system, or clutch — only chain and bar maintenance.

Battery-powered chainsaws from Stihl (MSA series), Husqvarna (T-series), and others approach the performance of small-to-medium petrol saws for cross-cutting and limbing, though they cannot compete with 70+ cc professional felling saws. Battery life limits continuous cutting to approximately 30–60 minutes per charge,²⁵ and the lithium-ion batteries are themselves finite and degrading (Doc #35). Battery saws are most valuable as supplements to the petrol fleet — used for lighter tasks while reserving petrol saws for heavy felling.

Strategic deployment: Electric chainsaws should be concentrated at fixed processing sites (mill yards, firewood depots, road-accessible landings) and near-grid woodlots. For bush felling away from power, petrol chainsaws and eventually crosscut saws remain the only options.

---

6. MANUAL FORESTRY TOOLS — THE LONG-TERM SOLUTION

6.1 The crosscut saw

The crosscut saw was the primary tree-felling tool worldwide before chainsaws became widely available in the 1950s.²⁶ In NZ, crosscut saws were standard in bush logging operations through the 1950s, with chainsaws progressively displacing them from the late 1940s onward. NZ’s kauri logging industry in Northland and West Coast rimu and beech operations used crosscut saws for decades.

Types:

• Two-person felling saw: A long, flexible blade (typically 1.5–2.1 metres) with handles at each end. Designed for horizontal cuts to fell standing trees. The blade has large teeth with deep gullets to clear sawdust from the cut. Properly sharpened and operated by a skilled two-person team, a felling crosscut can cut surprisingly fast — though nowhere near chainsaw speed.
• One-person crosscut (bucking saw): A shorter saw (0.9–1.5 metres) with a handle at one end and sometimes a supplementary handle, used for cutting fallen logs to length. The operator pulls on the working stroke; the saw rides back on the return. Slower than a two-person saw but requires only one operator.
• Bow saw (bush saw, Swede saw): A tubular steel frame holding a narrow replaceable blade under tension. Fast for small-diameter work (up to 20–25 cm). Standard bush tool in NZ for pruning and light clearing. Blades are consumable but thin, and could potentially be produced from NZ steel.

6.2 Crosscut saw sharpening and maintenance

A crosscut saw requires skilled sharpening — more so than a chainsaw chain. An improperly sharpened crosscut saw is a miserable tool that jams, stalls, and exhausts the operators. A properly sharpened one is a pleasure to use. The difference is entirely in the sharpening.

Crosscut saw tooth patterns: Most felling crosscut saws use a “cutting and raking” tooth pattern — pairs of cutting teeth (which sever wood fibres at the sides of the kerf) alternating with raker teeth (which clear the severed fibres from the kerf). Some patterns use lance teeth (a modified cutter). The specific pattern must be identified before sharpening, as each type has a different filing procedure.²⁷

Sharpening procedure (general):

1. Secure the saw in a saw vise — a clamp that holds the blade rigid during filing. The vise can be fabricated from hardwood or welded from steel.
2. Examine the tooth pattern. Identify cutters and rakers.
3. Joint the teeth: Run a flat mill file along the top of the teeth to establish a uniform height datum. This identifies which teeth are high (more metal to remove) and which are low (less to remove).
4. File the cutting teeth: Using a flat or slim taper file, file each cutting tooth to the correct angle and bevel. Cutters are filed at an angle to the blade (typically 12–18 degrees) to create a slicing action. File alternating teeth from one side, then reverse and file the other side.
5. File the raker teeth: Rakers are filed flat across the top, slightly below the cutter tips (0.5–1.0 mm lower), using the raker gauge as a guide. If rakers are too high, the saw cannot feed into the cut. If too low, it digs in and jams.
6. Set the teeth: The cutting teeth must be bent slightly outward (set) to create a kerf wider than the blade thickness, preventing the saw from binding. Setting is done with a saw set tool — a hand tool that bends each tooth a precise amount. Over-setting causes a wide, wasteful kerf; under-setting causes binding.
7. Check and true the blade. A crosscut blade must be flat and straight. Kinks and bows are straightened with a saw-setting hammer on a flat anvil.

This is a skilled operation. A competent crosscut saw sharpener is as valuable as the saw itself. In the logging camps of the pre-chainsaw era, saw filers were specialist tradespeople.²⁸ Under recovery conditions, training crosscut saw filers should be a specific priority within the heritage skills programme (Doc #160).

6.3 Axes and hatchets

Axes remain essential forestry tools regardless of chainsaw availability. They are used for limbing (removing branches from a felled tree), notching (cutting the felling notch), splitting, and dozens of camp and bush tasks. Axes are among the simplest tools to maintain — they require only a file or grindstone for sharpening, and can be resharpened hundreds of times before the head is reduced below useful size.

Sharpening: A felling axe should have a convex (slightly curved) bevel, not a flat grind. The convex bevel prevents the axe from sticking in the wood. Sharpen by hand with a mill bastard file, following the existing bevel, or on a bench grinder with a fine wheel (avoid overheating, which draws the temper). The cutting edge should be sharp enough to shave paper but need not be razor-sharp — forest axes work primarily by fracturing wood fibres, not slicing them.

Handle replacement: Axe handles break. NZ-grown ash (Fraxinus excelsior) and hickory (Carya spp.) are the traditional handle materials, though NZ’s stocks of these species are limited. Manuka (Leptospermum scoparium) is dense and shock-resistant, and was used by Maori for hand implements. Radiata pine is too soft and weak for axe handles. Macrocarpa and some eucalyptus species are potential alternatives, though not ideal. Handle shaping is a skill that can be learned from pattern in a few hours but perfected over months.²⁹

6.4 Wedges and felling equipment

Felling large trees with a crosscut saw requires wedges to control the direction of fall and to prevent the saw from binding in the kerf as the tree begins to lean. Wedges can be:

• Steel wedges: Forged from scrap steel by a blacksmith (Doc #92). A straightforward forging project — tapered steel plate, hardened at the thin end.
• Plastic wedges: Existing stocks. Lighter than steel and do not damage the saw if struck accidentally.
• Hardwood wedges: Traditional emergency option. Less durable but functional and producible anywhere.

Other manual felling equipment includes:

• Log tongs: For gripping and moving logs. Fabricated from steel bar.
• Cant hooks and peaveys: Lever tools for rolling and positioning logs. The cant hook has a swinging metal hook on a wooden handle; the peavey has a fixed spike. Both are NZ-producible from steel and timber.
• Timber jacks: Lever devices for lifting one end of a log off the ground to allow a bucking cut underneath without cutting into the ground (which would destroy a crosscut saw or chain).

---

7. DOMESTIC MANUFACTURE OF FORESTRY TOOLS

7.1 What NZ can produce

Tool	Manufacturing difficulty	Materials	NZ capability
Felling axes	Low — blacksmithing	Scrap steel, hardwood handles	Immediately producible (Doc #92)
Steel wedges	Low — blacksmithing	Scrap steel	Immediately producible
Cant hooks, peaveys	Low — blacksmithing + woodwork	Steel, timber	Immediately producible
Crosscut saw blades	Moderate — requires quality steel and saw-doctor skills	High-carbon steel from Glenbrook, heat treatment	Achievable Phase 2–3
Bow saw blades	Moderate — similar to crosscut but thinner	Spring steel or high-carbon strip	Achievable Phase 2–3
Chainsaw chains	High — precision stamping, case hardening, assembly	Steel strip, specialised tooling	Uncertain — possibly Phase 3–4
Chainsaw bars	Moderate-high — requires precision grinding	Alloy steel plate	Achievable Phase 3–4
Round files for chain sharpening	Moderate — requires drawing hardened steel wire to precise diameter, cutting teeth, and heat treating to correct hardness	Tool steel wire (from Glenbrook or scrap), heat treatment (Doc #92), wire drawing capability (Doc #91)	Achievable Phase 2–3

7.2 Crosscut saw manufacture

A crosscut saw blade is a piece of high-carbon steel (approximately 0.6–0.9% carbon), hardened and tempered to a spring temper (approximately Rockwell C 40–45), cut to shape, and fitted with teeth.³⁰ The manufacturing process:

1. Steel sourcing: NZ Steel at Glenbrook (Doc #89) produces carbon steel. Crosscut saw blade steel needs to be thinner (approximately 1.2–1.6 mm for the body, thicker at the tooth line) and higher-carbon than typical structural steel. Producing suitable sheet or strip steel may require specific rolling and metallurgical work at Glenbrook, or sourcing from existing stocks of spring steel (leaf springs from vehicles are approximately the right carbon content and thickness, though shorter than a saw blade requires).
2. Profile cutting: Cut the blade to shape — a long taper from handle to tip. This can be done with a plasma cutter, oxy-acetylene torch, or by shearing if appropriate equipment is available.
3. Tooth cutting: Stamp or grind the tooth pattern into the blade edge. A punch press or purpose-made tooth cutter is the production method; hand filing is possible but extremely slow for production quantities.
4. Heat treatment: Harden the blade by heating to approximately 800–830 degrees C and quenching in oil (used motor oil, tallow, or purpose-prepared quenching oil — see Doc #34 for oil availability), then temper at approximately 350–400 degrees C to achieve spring temper. Incorrect heat treatment produces a blade that is either too brittle (cracks in use) or too soft (teeth deform). This requires metalworking skill and a reliable forge or heat-treatment oven (Doc #92).³¹
5. Setting and sharpening: Set and sharpen the teeth as described in Section 6.2.
6. Handles: Turned or carved from hardwood.

Timeline to production: Assuming Glenbrook steel, blacksmithing and heat-treatment skills from Doc #92, and machining support from Doc #91, producing functional crosscut saws is realistic within 1–3 years of concerted effort. The first saws will be inferior to pre-war manufactured saws — thicker, heavier, with less uniform heat treatment. Quality will improve with practice and refinement.

7.3 Chainsaw chain manufacture

Chainsaw chain manufacture is significantly harder than crosscut saw production. A chainsaw chain is an assembly of precisely shaped components:

• Drive links: Stamped from steel strip, with a tang that fits the bar groove and a hole for the rivet. Must be dimensionally consistent to mesh with the drive sprocket.
• Tie straps: Connect drive links to each other and to the cutters. Stamped from steel strip.
• Cutters (left and right): The cutting elements. Require a specific geometry (top plate angle, side plate angle, depth gauge height), chrome plating or case hardening of the cutting edge, and consistent dimensions. These are the hardest component to reproduce.
• Rivets: Hold the assembly together while allowing the links to pivot.

Manufacturing a chainsaw chain requires stamping dies for each component type, a riveting setup, heat treatment capability (cutters must be case-hardened to hold an edge while remaining ductile enough not to shatter), and quality control to ensure dimensional consistency across the hundreds of components in a single chain.³²

This is 1940s-era manufacturing technology — there is nothing about it that is beyond NZ’s theoretical capability. But it requires purpose-built tooling, and the tooling itself must be made (stamping dies, forming tools, riveting fixtures). A realistic estimate for NZ to produce functional chainsaw chain from scratch is 3–5 years of dedicated effort involving tool and die makers (Doc #91), blacksmiths for heat treatment (Doc #92), and significant experimentation.

A possible intermediate step: If NZ cannot produce complete chains, it may be possible to produce replacement cutters that can be riveted onto salvaged chain bodies (drive links and tie straps) from worn chains whose cutters are exhausted but whose body links are still serviceable. This is simpler than full chain manufacture and extends the usable chain supply.

---

8. TRAINING PRIORITIES AND WORKFORCE DEVELOPMENT

8.1 Current skills base

NZ’s professional forestry sector employs approximately 6,000–8,000 workers in logging and associated activities.³³ Most professional logging workers are competent chainsaw operators with basic field sharpening skills. However, the depth of maintenance knowledge varies — some operators maintain their own saws to a high standard; others rely on service workshops for anything beyond basic sharpening.

The broader chainsaw-owning population (farmers, arborists, lifestyle-block owners, hobby users) numbers in the hundreds of thousands, with widely varying skill levels. Many owners sharpen chains infrequently or not at all, relying on replacement chains.

8.2 Training needs

Immediate (Phase 1):

• Maintenance discipline for all operators. A short course (4–8 hours) covering correct sharpening, bar care, engine maintenance, and storage. Delivered at regional forestry centres, farming field days, and community workshops. Target: every chainsaw owner in NZ.
• Advanced maintenance for professional operators. A more intensive course (2–3 days) covering engine diagnosis, carburetor adjustment, bar reconditioning, sprocket assessment, and maximising consumable life. Target: all professional logging crews and sawmill operators.

First year (Phase 1–2):

• Crosscut saw sharpening. A specialist course requiring 2–5 days of instruction plus supervised practice. The skill of crosscut saw filing is substantially more difficult than chainsaw chain sharpening and requires experienced instruction. Target: at least two trained crosscut saw filers per forestry region.
• Crosscut sawing technique. Two-person felling with crosscut saws, including notch cutting, wedge use, felling direction control, and bucking. This is a physical skill requiring weeks of practice to develop the rhythm and coordination that makes crosscut sawing efficient. Target: at least 10 trained two-person crews per forestry region within the first year.

Years 2–5 (Phase 2–3):

• Expanded crosscut workforce. As petrol chainsaws become increasingly constrained, the crosscut sawing workforce must grow. Training scales up to produce hundreds of competent operators nationwide.
• Saw doctoring. The specialist skill of maintaining and manufacturing crosscut saws and bandsaw blades (see Section 7 above). A saw doctor’s training takes 1–3 years under a skilled practitioner. NZ may have a small number of retired saw doctors whose knowledge should be captured (Doc #33).³⁴

8.3 Safety

Chainsaws and felling tools are among the most dangerous equipment used in any industry. NZ forestry has a historical record of high injury and fatality rates. WorkSafe NZ has published chainsaw safety guidelines, and the New Zealand Qualifications Authority (NZQA) unit standards for chainsaw use (e.g., Unit Standards 6916, 6917, 6918) specify competency requirements.³⁵

Under recovery conditions, safety training must not be sacrificed to urgency. An untrained chainsaw operator is a liability — the productivity lost to injury (and the medical resources consumed) far outweighs the time invested in proper training. Crosscut saw work also has significant hazards — falling trees, springing saws, rolling logs — and requires training that addresses these risks.

---

CRITICAL UNCERTAINTIES / KEY RISKS

Uncertainty	Why it matters	Resolution path
Total NZ chainsaw stock and condition	Determines the fleet size available for managed deployment	National census (Doc #8)
Consumable stocks (chains, bars, files, sprockets) in NZ distribution network	Determines the timeline before manual methods become necessary	Distributor inventory audit (Doc #1)
Number of surviving crosscut saw practitioners	Determines urgency of heritage skills preservation	Census + heritage skills programme (Doc #160)
Condition of existing crosscut saws in NZ	Many are in collections and sheds; condition unknown	Inventory and assessment
Tallow and plant oil performance as bar lubricant in NZ conditions	Affects chain and bar wear rates under substitute lubricants	Empirical testing (Recommended Action #6)
Glenbrook steel suitability for saw manufacture	Determines whether NZ-made crosscut saws are achievable	Metallurgical assessment with NZ Steel (Doc #89)
Chainsaw chain domestic manufacture feasibility	Extends the chainsaw era if achievable; very high payoff	Tool-and-die feasibility study (Doc #8)
Electric chainsaw fleet size and distribution	Determines the potential for shifting to electric near grid	Census (Doc #8)
Crosscut sawing training scalability	Can NZ train enough crosscut operators before they are needed?	Pilot programme in first year

---

CROSS-REFERENCES

Document	Relationship
Doc #34 — Lubricant Production	Bar oil substitutes (tallow, lanolin, canola); two-stroke oil substitutes (castor oil)
Doc #53 — Fuel Allocation	Petrol supply for chainsaws — the binding fuel constraint
Doc #56 — Wood Gasification	Wood gas for log transport vehicles; wood gas cannot power chainsaws
Doc #89 — NZ Steel: Glenbrook	Steel for crosscut saw and tool manufacture
Doc #91 — Machine Shop Operations	Precision metalwork for saw manufacture; bar reconditioning
Doc #92 — Blacksmithing	Axe, wedge, and tool production; heat treatment for saw blades
Doc #99 — Timber Processing	The broader forestry system this document supports — harvesting, milling, drying
Doc #102 — Charcoal Production	Charcoal as forge fuel for saw manufacture
Doc #105 — Wire and Fencing	Wire for chainsaw chain (if local manufacture attempted)
Doc #157 — Trade Training	Chainsaw and crosscut training within the trade training framework
Doc #160 — Heritage Skills	Capturing crosscut sawing, saw filing, and manual felling knowledge from aging practitioners
Doc #8 — National Census	Chainsaw inventory, crosscut saw inventory, skills identification
Doc #1 — Stockpile Strategy	Consumable requisition framework for chains, bars, files
Doc #35 — Batteries	Battery constraints for cordless chainsaws

---

FOOTNOTES

---

1. Professional chainsaw operational life: major manufacturers (Stihl, Husqvarna) rate professional saws for approximately 1,500–2,000 hours of operation before major overhaul (piston, cylinder, bearings). Actual life depends heavily on maintenance — particularly air filter discipline and correct fuel mix. See manufacturer service manuals. Under recovery conditions with reduced daily operating hours, a well-maintained saw could serve 5–15 years before major engine work.↩︎

2. NZ chainsaw ownership estimate is not available from published statistics. NZ had approximately 1.9 million households in the early 2020s (Stats NZ). Chainsaw ownership rates in rural and semi-rural households are high; urban ownership is lower. Professional forestry, arborist, and farm use adds significant numbers. A total NZ chainsaw population of several hundred thousand is a reasonable order-of-magnitude estimate requiring verification through the census (Doc #8).↩︎

3. Manual forestry in NZ was standard through the 1950s. The NZ Forest Service used both crosscut saws and early chainsaws in the post-war period, with chainsaws becoming dominant by the early 1960s. See Reed, A.H. (1953), The Story of the Kauri; and Roche, M. (1990), History of New Zealand Forestry. The last professional bush workers to use crosscut saws routinely would now be in their 80s and 90s.↩︎

4. Crosscut saw vs. chainsaw productivity comparisons are based on historical forestry records and modern re-enactment data. A skilled two-person crosscut crew in NZ radiata pine can fell a 40 cm tree in approximately 15–30 minutes; a skilled chainsaw operator in 1–2 minutes. See also Doc #99 for broader timber harvesting context. Productivity varies significantly with tree species (hardwoods take longer), diameter, operator skill, and tool sharpness.↩︎

5. Historical crosscut sawing output: NZ bush sawyer records from the kauri milling era indicate that skilled two-person crews could fell and buck 3–8 cubic metres of timber per day depending on tree size and conditions. See Halkett, J. and Sale, E.V. (1986), The World in a Forest: History of Bush Tramways and Timber Milling in the Kaimai Range. These figures are consistent with North American historical forestry data.↩︎

6. Crosscut saw vs. chainsaw productivity comparisons are based on historical forestry records and modern re-enactment data. A skilled two-person crosscut crew in NZ radiata pine can fell a 40 cm tree in approximately 15–30 minutes; a skilled chainsaw operator in 1–2 minutes. See also Doc #99 for broader timber harvesting context. Productivity varies significantly with tree species (hardwoods take longer), diameter, operator skill, and tool sharpness.↩︎

7. Historical crosscut sawing output: NZ bush sawyer records from the kauri milling era indicate that skilled two-person crews could fell and buck 3–8 cubic metres of timber per day depending on tree size and conditions. See Halkett, J. and Sale, E.V. (1986), The World in a Forest: History of Bush Tramways and Timber Milling in the Kaimai Range. These figures are consistent with North American historical forestry data.↩︎

8. Chainsaw specifications from manufacturer data. Stihl (German-manufactured, dominant NZ professional brand) and Husqvarna (Swedish, significant NZ market share) produce the majority of professional-grade chainsaws sold in NZ. Consumer brands (Ryobi, Makita, Echo) account for a significant share of total units but smaller share of professional forestry use. See manufacturer product specifications at stihl.co.nz and husqvarna.com.↩︎

9. Rim sprockets vs. spur sprockets: rim sprockets are universally preferred for professional use because they allow sprocket replacement without replacing the clutch drum. Oregon, Stihl, and Husqvarna all produce rim sprocket systems. Under recovery conditions, sprocket replacement extends the useful life of the clutch assembly significantly.↩︎

10. Chainsaw chain geometry and sharpening specifications from Oregon (the dominant chain manufacturer) and Stihl technical documentation. Cutter dimensions, filing angles, and depth gauge specifications are chain-type-specific. The 5–10 sharpening estimate per cutter is based on total material available for removal between new cutter length (~8–9 mm) and minimum usable length (~4 mm), with approximately 0.2–0.3 mm removed per filing. Actual numbers vary with filing technique and chain wear pattern.↩︎

11. Chainsaw file life: a hardened steel round file will sharpen approximately 3–8 chains before becoming too dull for effective use. This figure is from professional logging experience and file manufacturer guidance. File life varies with steel quality, filing technique (steady pressure, lifting on return stroke), and chain condition (dirty chains wear files faster). See also Doc #39, footnote 45.↩︎

12. Guide bar life: a properly maintained bar lasts approximately 3–5 chains. The primary wear modes are groove widening (from chain side play), rail narrowing (from chain circulation), and nose sprocket failure. Periodic bar flipping and rail dressing extend bar life. See Oregon “Guide Bar Maintenance” technical literature.↩︎

13. Professional chainsaw operational life: major manufacturers (Stihl, Husqvarna) rate professional saws for approximately 1,500–2,000 hours of operation before major overhaul (piston, cylinder, bearings). Actual life depends heavily on maintenance — particularly air filter discipline and correct fuel mix. See manufacturer service manuals. Under recovery conditions with reduced daily operating hours, a well-maintained saw could serve 5–15 years before major engine work.↩︎

14. The productivity and wear consequences of operating dull chains are well-documented in chainsaw manufacturer training materials and professional logging manuals. Stihl’s professional training program emphasizes sharpening as the single most important maintenance skill. See also: Persson, P. (1975), “The mechanics of cutting wood with a chainsaw,” Royal College of Forestry, Stockholm.↩︎

15. Chainsaw chain geometry and sharpening specifications from Oregon (the dominant chain manufacturer) and Stihl technical documentation. Cutter dimensions, filing angles, and depth gauge specifications are chain-type-specific. The 5–10 sharpening estimate per cutter is based on total material available for removal between new cutter length (~8–9 mm) and minimum usable length (~4 mm), with approximately 0.2–0.3 mm removed per filing. Actual numbers vary with filing technique and chain wear pattern.↩︎

16. Chainsaw chain geometry and sharpening specifications from Oregon (the dominant chain manufacturer) and Stihl technical documentation. Cutter dimensions, filing angles, and depth gauge specifications are chain-type-specific. The 5–10 sharpening estimate per cutter is based on total material available for removal between new cutter length (~8–9 mm) and minimum usable length (~4 mm), with approximately 0.2–0.3 mm removed per filing. Actual numbers vary with filing technique and chain wear pattern.↩︎

17. Diamond chainsaw sharpeners: various manufacturers produce diamond-coated sharpening tools for chainsaw chain. These include rotary grinding wheels (e.g., Granberg, Timberline) and flat diamond files. Diamond abrasive lasts effectively indefinitely for the relatively soft chrome-hardened steel of chainsaw cutters. NZ stock of these tools is unknown but should be identified and allocated to professional forestry users.↩︎

18. Guide bar life: a properly maintained bar lasts approximately 3–5 chains. The primary wear modes are groove widening (from chain side play), rail narrowing (from chain circulation), and nose sprocket failure. Periodic bar flipping and rail dressing extend bar life. See Oregon “Guide Bar Maintenance” technical literature.↩︎

19. Tallow as bar oil: animal fat has been used as a machinery lubricant since antiquity and functions adequately as a chain and bar lubricant. Performance is inferior to purpose-made bar oil — tallow is less tacky (flings off the chain more readily at high speed), solidifies at lower temperatures, and attracts dirt. In NZ’s temperate climate, tallow is serviceable for 8–10 months of the year in most regions. See Doc #34 for detailed lubricant assessment.↩︎

20. Lanolin production in NZ: NZ’s wool scouring industry produces lanolin as a byproduct. NZ is one of the world’s largest lanolin producers, with several thousand tonnes per year extracted during wool scouring. Lanolin is an excellent general-purpose lubricant with natural tackiness and water resistance. See Doc #34 for detailed assessment of NZ lubricant substitutes.↩︎

21. Two-stroke fuel mix ratios from manufacturer specifications. Stihl specifies 50:1 for its HP Ultra oil; 25:1 for lower-quality oils. Husqvarna specifies 50:1. The exact ratio depends on the oil used — higher-quality oils provide adequate lubrication at lower concentrations. With castor oil substitute, a richer mix (25:1 to 40:1) is advisable as castor oil’s lubrication properties differ from synthetic two-stroke oils.↩︎

22. Castor oil as two-stroke lubricant: castor oil was the standard two-stroke engine lubricant before the development of petroleum-based and synthetic two-stroke oils. It remains used in some high-performance applications (racing). Castor oil provides excellent lubrication but produces more carbon deposits than modern oils, requiring more frequent spark plug and exhaust port cleaning. Castor beans grow in NZ’s warmer regions (Northland, Bay of Plenty, Gisborne) and the plant is naturalised in some areas, though not commercially cultivated at scale.↩︎

23. Small-engine spark plug life: a standard spark plug (NGK BPMR7A, the type used in most Stihl and Husqvarna saws) can be cleaned and re-gapped many times. The electrode erodes slowly in normal use, and total life can exceed 500–1,000 hours with regular cleaning. NZ’s stock of small-engine spark plugs (held by automotive and outdoor power equipment distributors) is likely substantial relative to the reduced consumption rate under recovery conditions.↩︎

24. NZ plantation forest distribution: approximately 90% of NZ’s 1.7 million hectares of planted production forest is radiata pine, concentrated in the Central North Island (Kaingaroa, Tokoroa, Taupo districts), Northland, Bay of Plenty, Nelson-Marlborough, and Canterbury. These regions all have grid electricity access. Source: MPI National Exotic Forest Description (NEFD) and NZ Forest Owners Association statistics.↩︎

25. Battery chainsaw runtime: manufacturer specifications for current-generation battery chainsaws (e.g., Stihl MSA 220 with AP 300 S battery, Husqvarna T540i XP with BLi 300) indicate approximately 30–60 minutes of cutting time per charge depending on wood type, diameter, and cutting intensity. Runtime at full load in hardwood is at the lower end; intermittent cutting in softwood extends toward the upper end. Source: manufacturer product specifications at stihl.co.nz and husqvarna.com.↩︎

26. Chainsaw history: the first commercially successful chainsaws appeared in the 1920s–1930s (heavy, two-person machines). Light one-person chainsaws became available in the late 1940s and rapidly displaced crosscut saws in professional forestry through the 1950s. See: Stihl company history; and Drushka, K. and Konttinen, H. (1997), Tracks in the Forest: The Evolution of Logging Machinery, Timberjack Group.↩︎

27. Crosscut saw tooth patterns: the standard reference for crosscut saw maintenance is USDA Forest Service, Crosscut Saw Manual (MTDC 7771-2508), which describes the common tooth patterns (champion, tuttle, lance, perforated lance, Great American) and sharpening procedures for each. This manual should be reprinted and distributed to all forestry operations as part of the printing programme (Doc #29).↩︎

28. Saw filers as specialist tradespeople: in the pre-chainsaw logging era, large bush camps employed dedicated saw filers whose sole job was maintaining crosscut saws and axes. The skill was considered a distinct trade, typically learned through apprenticeship over several years. The last professional NZ bush camp saw filers retired decades ago. See: Roche, M. (1990), History of New Zealand Forestry.↩︎

29. Axe handle materials: the traditional NZ preference was imported American hickory, though NZ-grown ash was also used. Manuka was used in pre-European and early colonial NZ for handles and implements because of its density and shock resistance. For modern recovery use, any wood with good strength, shock resistance, and straight grain is suitable — identifying the best NZ-available species for handle timber would benefit from empirical testing.↩︎

30. Crosscut saw metallurgy: historical crosscut saws were produced from high-carbon crucible steel (Sheffield steel was the standard for quality saws). The carbon content of approximately 0.6–0.9% allows the blade to be hardened to spring temper — hard enough to hold an edge but flexible enough not to crack in use. See: Disston, H. & Sons, The Saw in History (1916), for historical saw manufacturing practices.↩︎

31. Heat treatment for saw blades: achieving the correct spring temper requires hardening the steel by heating to its austenitising temperature (approximately 780–830 degrees C for high-carbon steel) and quenching in oil, followed by tempering at approximately 350–400 degrees C. The resulting hardness (approximately Rockwell C 40–45) gives a blade that is hard enough to hold a cutting edge but flexible enough to bend without breaking. Incorrect heat treatment is the most likely failure mode for NZ-produced saws. See Doc #92 for heat treatment fundamentals.↩︎

32. Chainsaw chain manufacturing complexity: a modern chainsaw chain consists of stamped and formed components requiring dimensional consistency within approximately 0.1 mm. The cutters must be case-hardened (hard surface for edge retention, ductile core for impact resistance). Chrome plating of cutters, which provides the hard cutting surface on modern chains, requires electroplating capability that NZ may not have initially. Case hardening (carburising) is an alternative that NZ blacksmiths could achieve. See Doc #92, footnote 51 for additional detail.↩︎

33. NZ forestry workforce: approximately 6,000–8,000 workers are employed directly in logging operations, with additional workers in wood processing (sawmilling, treatment, distribution) totalling approximately 35,000 across the broader forestry and wood processing sector. Source: MPI forestry statistics and Stats NZ business demography data. See Doc #160, footnote 7.↩︎

34. Saw doctors — specialist tradespeople who maintain and manufacture saw blades — are a declining trade in NZ. Large sawmills (Red Stag Timber in Rotorua, Pan Pac in Napier) retain saw maintenance staff, some of whom have decades of experience with bandsaw and circular saw maintenance. These individuals may also hold relevant knowledge of crosscut saw sharpening, though crosscut maintenance is a somewhat different skill from bandsaw doctoring. Heritage skills preservation (Doc #160) should target these practitioners specifically.↩︎

35. WorkSafe NZ chainsaw safety guidance and NZQA unit standards for chainsaw use provide the NZ-specific safety framework for chainsaw operation. Unit Standards 6916 (Demonstrate knowledge of chainsaw use for horticulture or arboriculture), 6917 (Fell trees up to 200 mm), and 6918 (Fell trees 200–380 mm) specify competency requirements for different levels of chainsaw work. Under recovery conditions, these standards should be adapted as the basis for chainsaw training programmes.↩︎