クイックサマリー： シャーブレードのクリアランスは、切断点で測定した板厚の5〜10%に設定されます。6mmの軟鋼の場合、これは0.30〜0.60 mmの隙間を意味しますが、このパーセンテージはあくまで開始時の目安であり、最終的な絶対値ではありません。実際の素材でテストカットを行って実用値を確定し、隙間ゲージ（シックネスゲージ）を使用してブレード沿いの3点でクリアランスを検証してください。また、板厚の5%を超えるバリ高さが確認された場合は、クリアランスを再点検するトリガー（基準）として扱ってください。
技術ノート： シャーブレードのクリアランスとは、上下の切断エッジ間の垂直方向の隙間のことであり、板厚に対するパーセンテージで表されます。これは、切断面におけるせん断面と破断面の比率、バリの高さ、および1ストロークあたりのナイフへの負荷を左右します。Maxtor Metalのセットアップおよび品質管理（QC）ワークフローでは、クリアランスを固定の機械設定ではなく「材質固有のプロセスパラメータ」として扱い、ナイフの状態やエッジの丸み（刃先R）の測定値とともに、作業ごとに文書化しています。[→ See Maxtor Metal shear blade specifications and material options]
シャーブレードのクリアランスとは、切断点における上下刃のエッジ間の水平方向の隙間を指し、ギロチンシャーでは通常、固定値ではなく板厚に対するパーセンテージとして設定されます。この設定を誤った場合のコスト影響は決して無視できません。エッジ品質の不良によるストリップのスクラップ（端材廃棄）は、TCO（総所有コスト）の5%〜10%を占めており、この数値は再研磨サイクルを重ねるごとに蓄積・増대していきます。
The 5–10 percent rule is a starting range rather than a specification. Treat the machine manual as the authority, then find the working value by iterating on the actual sheet, blade sharpness and rake angle (Ursviken, 2025). Note the convention split: some suppliers state blade clearance per side, others state the blade-to-blade gap, so confirm which figure the Maxtor Metal shear blade specification uses before you dial anything in. Maxtor Metal works to the per-side reading, which doubles the number at the gap.
重要なポイント
- シャーブレードのクリアランスは板厚に対するパーセンテージであり、切断点で設定されます。
- 5〜10%の範囲はあくまで初期の目安であり、最終的な数値は機械の取扱説明書に従います。
- 記載されている数値が片側あたりのクリアランスなのか、上下の刃の総隙間なのかを確認してください。
- エッジ品質の不良は、ストリップのスクラップ（端材廃棄）を通じてTCO（総所有コスト）の5%〜10%を増大させます。
出典に関する注記：本ガイドは、公표されたせん断切断に関する参考文献（AHSSガイドライン、ispatguruのせん断プロセス文書、UrsvikenおよびSureayなどの設備メーカーの指導書）と、Maxtor Metal自身の現場での実務経験に基づき作成されています。独立した情報源からの数値はその旨を明記しており、メーカー内部の受入限界値を反映している場合は、適切にご判断いただけるよう明確に記載しています。
切断エッジのメカニズム（刃先挙動の力学）
Shear blade clearance decides how a cut fails, and that failure is what produces either a clean edge or a burr. The mechanism is worth understanding because it explains why the recommended band moves with material and thickness rather than staying fixed.
In short: clearance controls the split between smooth burnish and rough fracture on the cut edge — understanding this mechanism is what turns the 5–10% band from a guess into a tuning range.
Burnish and fracture zones
A sheared edge is not one surface. It is four zones stacked through the material thickness: rollover, where the blade first contacts and plastically deforms the sheet into a rounded, bent region; the burnish or shear zone, a smooth band formed while the blade compresses and rubs the material; the fracture or rupture zone, a rougher angled region where the crack propagates; and the burr, thin elongated metal pushed out at the exit edge (ispatguru, 2019; AHSSガイドライン, 2021).
Rollover and burr formation
Clearance sets the split between the smooth and rough portions of that edge. The burnish zone ends where crack initiation begins, so penetration depth equals rollover height plus burnishing zone height. The rough fracture zone then grows with ductility, thickness and clearance, which means a larger clearance shrinks the burnish share, enlarges the fracture share, and pushes more material into the burr (ispatguru, 2019).
Force, rake, and clearance interplay
The general shearing range runs from 2% to 10% of material thickness, and the correct point inside that range depends on the workpiece. Harder materials and greater thickness need larger clearance. Set it too wide and the edge comes out rounded and distorted with a burr and a higher shearing load; set it too tight and the blade leaves a double cut, sometimes called secondary shearing. Ductile material produces a taller burr at any given clearance (ispatguru, 2019).
That is the mechanism behind the band. The next section turns it into numbers.
5〜10%ルール
The 5–10 percent rule says the shear blade clearance should sit between 5% and 10% of the metal thickness you are cutting. That band is the starting point for mild steels, not a universal setting, and the AHSSガイドライン note that published recommendations place mild-steel die clearance at 5% to 10% of metal thickness. The same source flags a convention trap worth settling before you touch the machine: for punched holes, those figures are per-side values. Vendor charts on the open web often frame the identical 5%–10% band as the total blade-to-blade gap instead. Confirm which convention your chart uses before you convert a number into a shim stack, because a 10 mm mild-steel cut reads as 0.5–1.0 mm per side under one reading and 0.5–1.0 mm total under the other.
In short: the 5–10% band is a defensible starting range for mild steel, not a universal answer — the working value must be confirmed by test cut on the actual material, and the convention (per side vs total gap) must be established before any number is set.
Material-based bands
The band widens as the material gets stronger. The AHSS Guidelines put the range at roughly 6% for mild steel, rising to 16% or higher once tensile strength passes 1400 MPa, and note that ISO 16630 hole-expansion testing specifies 12% punch-to-die clearance while optimal clearance for advanced high-strength steel appears to be approximately 15%. Treat those as directional anchors rather than a lookup table: they come from a technical body’s guidance program, and the underlying figure is a historical baseline rather than a recent test series.
For AHSS and UHSS applications where standard D2 blades are reaching their clearance and wear limits, see the AHSSライン向け超硬合金インレイシャーブレードのROI（投資対効果）ガイド （詳細なTCO比較を掲載しています。）.
When to deviate
Deviate upward when the material work-hardens or when edge quality matters more than tool life. Deviate downward only when your press capacity is the binding constraint, since tighter clearance raises cutting force. The honest position is that 5%–10% is a starting point you tune from, not an answer you inherit.
Parallelism and thickness effects
Clearance is only as good as its consistency along the blade. A machine set to 8% at the ends but drifting to 11% mid-blade will burr in the middle and shear cleanly at the edges, which is why parallelism is checked separately from the nominal gap. Thicker stock amplifies the same error: the absolute gap grows with thickness, so a fixed mechanical misalignment becomes a larger percentage deviation.
調整・セットアップ標準作業手順書（SOP）
A repeatable shear blade clearance setup follows one sequence: baseline the gap, verify parallelism, lock, test cut, iterate. The steps below assume the machine is locked off, the blades are clean and correctly seated, and you have a feeler gauge set, a dial indicator with a magnetic base, and scrap of the material you are about to run. Budget 30 to 45 minutes for a first setup on a machine you do not know well.
In short: measure clearance at three points along the blade before every setup change, verify parallelism within 0.02 mm, lock the adjusters, then iterate from a test cut — the sequence matters because locking adjusters commonly shifts the gap.
Feeler gauge baseline
Set the upper blade to its lowest position and insert the feeler gauge stack at the left end, center, and right end of the blade. Three points is the minimum; add points every 500 mm on blades longer than 2 m. Adjust the gap until the gauge drags with light resistance rather than passing freely or binding. Record all readings before touching anything else, because the spread across those points tells you whether you are correcting clearance or parallelism.
Dial indicator calibration
Mount the dial indicator on the lower blade and sweep the upper blade through its stroke, recording readings at several positions along the length. Blades should sit within 0.02 mm of each other, and the gap needs immediate recalibration once it exceeds that. Note what kind of number this is: there is no single ISO standard that sets a shear-blade parallelism limit, so 0.02 mm is Maxtor Metal’s internal acceptance target, not an industry-mandated figure. The relevant general framework is dimensional and geometric tolerancing — ISO 286 defines the IT tolerance grades used for precision blade geometry (IT6 for cutting-edge position, parallelism to the holder reference face, and flatness; IT7 for length, width, and mounting-hole position), and ISO 2768 supplies general tolerances where a drawing carries no individual callout. Treat the 0.02 mm as a tighter-than-general shop specification built on that framework (ISO 286-1:2010; ISO 2768). The reason such a tight target is worth holding is mechanical: on a 3,000–4,000 mm blade, a 0.1–0.15 mm deviation across the length is enough to produce visible taper on the cut edge (consistent with precision blade geometry standards under ISO 286 / ISO 2768). Lock the adjusters and re-check the gap at the same three points; locking commonly shifts it.
Test cut and iteration
Run a slow test cut on scrap and read the edge. Burrs or tearing mean the gap is too large; rubbing or excessive tightness means it is too small. Change clearance in small increments and re-cut rather than adjusting several variables at once, then log the final gap, the material grade and thickness, and the indicator readings against the job number so the next setup starts from a known point.
Each regrind removes material from the blade thickness. For the shim calculation method that compensates for this dimensional change and restores correct overlap after each cycle, see the regrinding thickness reduction compensation and shim stack guide.
Verify your result: the test cut should shear cleanly with no visible taper along its length, and a repeat indicator sweep should hold the gap within 0.02 mm after the adjusters are locked.
現場事例：6mm厚S355材における過剰なバリの発生対策
The clearest way to see why 5–10% is a starting rule and not a fixed answer is to walk through a commissioning-style troubleshooting case. This is a representative field case built on documented industry practice rather than a measured customer study: the machine, material and measurement sequence reflect how this problem typically appears on a hydraulic guillotine shear, and the underlying rules — the 5–10% band, the ~10% structural-steel practice, and multi-point feeler-gauge verification — are all publicly documented.
In short: this case demonstrates that a clearance value can sit inside the published 5–10% range and still produce unacceptable edge quality — the percentage is the starting calculation, and the cut edge is the verification tool.
The situation
| パラメータ | 価値 |
|---|---|
| 用途 | Hydraulic guillotine shear |
| 材料 | S355 structural steel |
| Nominal thickness | 6.0 mm |
| Measured thickness | 5.94–6.06 mm across the test sheets |
| ブレード | Hardened cold-work tool-steel shear blades |
| Initial clearance | ~0.30 mm |
| Target window | ~0.30–0.60 mm (5–10% starting rule) |
The problem appeared after the machine was switched from thinner sheet to 6 mm structural steel. The operator kept the previous clearance setting rather than recalculating the gap from the new material thickness — a common error where clearance is treated as a fixed machine setting instead of a material-dependent process parameter. The first test cuts showed a noticeably larger burr on the underside of the cut edge, a relatively short burnished zone, and a more irregular fracture zone. The operator suspected dull blades and considered replacing them.
Attempt 1 — replace the blades (rejected)
The first response was to suspect blade wear. Inspection, however, showed the cutting edges were still serviceable — no significant chipping or abnormal rounding. Replacing the blades without correcting the clearance would have treated the symptom rather than the process condition, so the next step was to verify the actual gap.
Measurement sequence
The machine was stopped and isolated per the site’s maintenance procedure. Blade seats were cleaned and checked for trapped scale, chips and debris. Sheet thickness was measured at several points with a micrometer rather than trusting the nominal 6 mm designation. Clearance was then measured at the left, center and right portions of the cutting length with calibrated feeler gauges. The machine manufacturer’s definition of clearance was used throughout the adjustment. This multi-point approach follows published shear-machine guidance, which requires clearance verification at several points along the blade rather than assuming the machine’s nominal setting equals the actual gap — Mittler Bros. and other shear manuals specify checking left, center and right with feeler gauges, and the Australian Steel Institute notes that optimum clearance depends on both material properties and thickness.
Attempt 2 — keep the 5% setting (insufficient)
After measurement, the initial gap was approximately 0.30 mm — about 5% of the measured 6 mm thickness:
6.0 mm × 5% = 0.30 mm
That value was technically inside the general 5–10% starting range, yet edge quality remained unsatisfactory. This is the key point: a value can sit inside the published percentage range and still not be the optimum setting for a particular machine-and-material combination. Clearance is also affected by blade condition, blade geometry, machine rigidity, alignment, and the mechanical properties of the workpiece. Betenbender’s shear guidance makes the same observation for steel work — roughly 10% of thickness usually gives a good cut edge, and clearance may be increased for harder or thicker material, but not beyond about 15%.
Attempt 3 — increase clearance (resolved)
Clearance was increased progressively toward approximately 0.50–0.55 mm, corresponding to roughly 8–9% of the 6 mm material thickness, then a fresh test cut was made under the same material and machine conditions. Edge quality improved visibly. The important caveat: this is not a claim that 0.50 mm is universally correct for S355 — it is simply the working setting found in this troubleshooting example. Published material studies make the same point about clearance being material-specific: voestalpine’s ALFORM technical data compares 4%, 10% and 16% clearance on 3 mm ALFORM 700 M and shows the cut-section geometry changes markedly with the ratio, with excessive clearance increasing burr and edge denting while reducing the shearing-zone share.
Effect, recorded honestly
Rather than inventing precise burr-height numbers, a credible record notes the observable change:
| パラメータ | Initial condition | After adjustment |
|---|---|---|
| 材料 | S355 | S355 |
| Nominal thickness | 6 mm | 6 mm |
| Measured thickness | 5.94–6.06 mm | 5.94–6.06 mm |
| クリアランス | ~0.30 mm | ~0.50–0.55 mm |
| Clearance ratio | ~5% | ~8–9% |
| Blade condition | Serviceable | Same |
| Test batch | Same heat / comparable material | Same |
| バー | Pronounced / unacceptable | Visibly reduced |
| Cut edge | Irregular fracture zone | More uniform fracture |
| Blade change | Not required | Not required |
If a team wants to make this rigorous, the fields worth adding are burr height (mm), rollover height (mm), burnished-zone and fracture-zone percentages, cut-angle deviation, machine hydraulic pressure, number of strokes, and blade edge radius.
The takeaway: the 5–10% rule provided the starting window; the test cut identified the working point. The percentage is the starting calculation — the cut edge is the verification tool.
This chain is worth internalising: 5–10% rule → 6 mm S355 gives a 0.30–0.60 mm starting window → measurement shows 0.30 mm gives poor edge quality → step up to ~0.50–0.55 mm → test cut confirms the improvement → do not market 0.50 mm as a “standard value” → every material, thickness and machine combination must be verified by test cut. The AHSS Guidelines reinforce why: clearance is not an isolated variable — a smaller clearance raises cutting force and the demands on tool and machine alignment, while a larger clearance increases rollover and related effects.
品質管理（QC）とメンテナンス
In short: set a numeric burr height limit before the job starts, log clearance and material lot per job, and treat rising burr height or an edge radius above 0.2 mm as mandatory regrind triggers — not subjective judgements.
Burr height limits and triggers
Burr height is the fastest field check on a shear, and it is the one most often left unmeasured. Set a numeric limit before the job starts, then treat any exceedance as a trigger rather than a nuisance.
A practical default is 5% of material thickness. On 3 mm mild steel that is 0.15 mm, measurable with a deburring gauge or a bench micrometer across the burr crest. Project drawings and customer acceptance criteria override the default whenever they are tighter.
Two triggers should stop the line:
- Burr height above tolerance on two consecutive cuts after a clearance check.
- Edge radius at or above 0.2 mm, measured on the blade bevel with a radius gauge or a 20× magnifier.
The second trigger matters because edge rounding, not visible chipping, is what silently widens the effective clearance. A blade that looks serviceable can already be cutting 0.05 mm wider per side than the setup sheet says. As with the parallelism target, the 0.2 mm is a Maxtor Metal internal limit rather than an ISO-mandated value; published edge-radius ranges for industrial blades vary widely by application — some slitting guides cite 0.05–0.30 mm, disc-shear references hold below 0.05 mm, and general deburring practice references edge-break specifications such as ISO 13715. That spread is exactly why you set the limit against your own acceptance criteria rather than assuming one number fits every line.
For a measurement-based rotation trigger and audit-ready log template that standardises this decision across an entire blade inventory, see the 4枚刃リバーシブルブレードの回転スケジュールと再研磨基準に関する標準作業手順書（SOP）.
プロのヒント: Log clearance, material lot, and burr height per job in one sheet. After a few weeks the log shows whether drift tracks a specific material lot, a specific operator, or the blade itself, which turns regrind scheduling from guesswork into a trend line.
Defect diagnosis and corrective actions
Match the defect to the cause before touching the blade. Most burr and edge complaints trace back to one of four conditions, and each has a different fix.
| 欠陥 | 考えられる原因 | 是正措置 |
|---|---|---|
| Tall, rolled burr on one side | Clearance too wide on that side | Re-check parallelism, reduce gap toward the lower band |
| Short, brittle burr with edge chipping | Clearance too tight | Open the gap, inspect the bevel under 20× magnification |
| Burr varies along the cut length | Blade not parallel or ram misalignment | Re-shim and verify straightness before the next setup |
| Clean cut, sudden burr spike mid-run | Edge wear or chipping | Measure edge radius, then decide regrind or replace |
When chipping appears suddenly or in a consistent location along the blade, the defect pattern itself carries diagnostic information. For a fracture surface analysis workflow that identifies whether the root cause is fatigue (clearance or grinding error) or impact (overload or hardness mismatch), see the shear blade edge chipping root cause guide.
That last decision follows a chipping-depth ladder. Light chipping under 0.2 mm clears with standard stock removal of 0.25–0.35 mm. Moderate chipping between 0.2 mm and 0.5 mm needs deeper removal and a 20× inspection of the bevel. Severe chipping above 0.5 mm means scrap or a major removal that can push the blade past its dimensional safety limit. The floor on any regrind is 0.254–0.381 mm of stock removal, because micro-fractures from running a blade past its sharpening window penetrate 0.25–0.40 mm below the bevel and will surface again if that layer is left in place (Maxtor Metal regrind-or-replace criteria for shear blades, retrieved 2026-08-27).
For a full analysis of how D2 and SKD11 carbide microstructure affects chipping depth and regrind frequency, see the D2 vs SKD11 tool steel shear blade selection guide.
Maxtor Metal’s own QC workflow ties this together: blades are logged against job and material lot, regrind is triggered when edge radius reaches 0.2 mm or burr height exceeds project tolerance, and every returned blade is re-verified for straightness under 0.02 mm/m, parallelism under 0.015 mm, and hardness across the full length before it goes back into rotation. These too are internal acceptance limits, set tighter than the general ISO 2768 / ISO 286 framework rather than drawn from a single published shear-blade standard. The point of the record is not the paperwork. It is knowing which of your four-edge reversible blades still has usable edges and which one is one bad cut away from a scrap decision.
FAQs:
Q: シャーブレードのクリアランスに関する「5〜10%ルール」とは何ですか？
A: シャーブレードのクリアランスを板厚の5%〜10%に設定するというものです。10mmの軟鋼の場合、これは0.5〜1.0 mmになります。引張強度が上昇するにつれてこの範囲は狭くなり、軟らかいアルミニウムは上限側に位置し、ステンレスや高張力鋼（HSLA）は下限側に位置します。これを初期の目安（出発点）とし、実際の素材ロット（ヒート）でのテストカットを行って確定させてください。
Q: シャーブレードのクリアランスは片側ですか、それとも総隙間ですか？
A: 公開されているチャートには両方の表記法（コンベンション）が存在するため、混同すると隙間が倍になってしまいます。Maxtor Metalでは、推奨する5〜10%を「片側あたりのクリアランス」として規定しています。したがって、10mmの軟鋼切断の場合、片側0.5〜1.0 mm（総隙間では1〜2 mm）となります。調整を行う前に、ご使用の機械メーカーがどちらの表記法を採用しているかを必ず確認してください。
Q: 6mm厚の軟鋼にはどのくらいのクリアランスを設定すべきですか？
A: 0.3〜0.6 mmから開始し、切断面の状態で確認してください。わずかなせん断面（光沢帯）を伴うクリーンで垂直なエッジが得られれば適正値に近い状態です。過度な垂れ角（ロールオーバー）やギザギザのバリが発生している場合は隙間が広すぎます。目視で判断せず、バリの高さを実際に測定してください。
Q: ステンレス鋼と軟鋼で同じクリアランスを使用できますか？
A: いいえ、できません。ステンレス、HSLA、その他の高張力鋼（ハイテン材）は、塑性変形しにくく早期に破断するため、通常は許容範囲の下限側に近い、より狭いクリアランスが必要です。軟鋼用のクリアランスのままステンレスを切断すると、エッジのクラック（端面割れ）やナイフの急速な摩耗を引き起こします。
Q: シャーブレードはどのくらいの頻度で再研磨すべきですか？
A: バリの高さが実用上のトリガー（基準）となります。一般的な実務では、バリの高さを板厚の10%未満に抑えることを目標としており、バリの高さの増加は工具の摩耗とクリアランスの拡大の両方を反映します（AHSSガイドライン）。AHSS（ハイテン材）の場合、バリの高さ単体では判断材料として不十分なため、切断面の品質（エッジ品質）の方がより良い指標となります。Maxtor Metalの社内ワークフローでは、「刃先半径（エッジR）が0.2 mmに達した場合」または「バリの高さがプロジェクトの許容値を超えた場合」のいずれか早い方を再研磨の基準として採用しています。
Q: シャーブレードの平行度はどのように確認しますか？
A: 機械をロックして停止させた状態で、マグネットベースに固定したダイヤルインジケーターを使用し、ブレードの全長にわたって測定します。Maxtor Metalでは、製造時に直線度0.02 mm/m未満、平行度0.015 mm未満であることを検証しています。これらは一般的なISO 2768 / ISO 286の公差フレームワークに基づく社内受入限界値であるため、すべての規格で一律に義務付けられている数値というよりも、稼働中の機械にとって実用的なベンチマークとなります。再研磨やナイフ交換を行った後は、必ず再点検してください。
Q: シャー切断で二度切れ（ダブルカット）が発生するのはなぜですか？
A: ダブルカットは通常、板厚に対してクリアランスが広すぎるために発生します。素材が隙間に落ち込んで曲がり、1回ではなく2回破断してしまいます。また、押え力（ホールドダウン圧）の不足や、ナイフの刃先が摩耗して切れ味が落ちていることが原因である場合もあります。ナイフのせいにする前に、クリアランスを許容範囲の下限側に絞り込み、押え圧を確認してください。
結論
シャーブレードのクリアランスは固定値ではなくセットアップ上の判断事項であり、5〜10%ルールは万能の答えではなく、十分な根拠を持つ出発点を提供します。この範囲は、エッジに生じるせん断面（光沢帯）と破断面の比率、および切断後に残る垂れ角（ロールオーバー）とバリの量の2つを同時にコントロールします。正しく設定すれば切断面はクリーンに保たれますが、この範囲から外れると、別の欠陥を引き起こすことになります。
制御されたプロセスと運任せのプロセスを分けるものは、標準化です。すべての作業で設定したクリアランスを記録し、対象となる材質と板厚を控え、バリのクレームを待つのではなく一定の周期でエッジの状態を点検してください。これらの記録に対して再研磨サイクルを追跡することで、ナイフが破損する前にエッジの摩耗を把握することができます。これは刃物自体の問題であると同時にワークフローの問題としても捉える必要があります。誰も記録に残さなければ、同じクリアランス値であってもシフトごとに挙動が異なってしまいます。
新しいシャーをセットアップする場合、または既存のシャーを標準化する場合は、数値を確定する前に、加工する材料の組み合わせやデューティサイクル（稼働負荷）に対してナイフの仕様を再確認してください。材料や用途が通常の範囲から外れている場合は、アプリケーションエンジニアに相談し、プロセスをどこでどのように逸脱させるべきか、その理由を含めて確認してください。
For the full Maxtor Metal shear blade range — material grades, dimensional tolerances, and regrind service options — see the precision shear blade product page.
This guide is written and reviewed by Jerry Chu, Technical Support Specialist in Maxtor Metal’s After-sales Service team. Jerry has 10 years of hands-on experience with industrial cutting blades across paper making, plastic granulation, metal slitting and slitting lines, and wood processing — applications where burr formation, edge quality, and dust generation all show up as real production problems rather than theory. That field background shapes the setup and QC guidance here: the focus on measurable triggers (burr height, edge radius, parallelism) rather than subjective “looks fine” judgements comes directly from troubleshooting these issues on customer lines.
Jerry holds PMP （Project Management Professional）および CMRP2 certifications, which support the process-discipline approach — logging, standardised setup, and scheduled inspection — that runs through this article.
Maxtor Metal is a manufacturer and supplier of custom, precision-ground industrial blades with over 15 years of experience, serving engineers, technical buyers, and equipment manufacturers worldwide. The company operates a quality management system certified to ISO 9001, and manufactures blades to customer drawings, sketches, or photos with material selection aimed at extending blade life. The internal tolerance and regrind figures quoted in this article come from that QC workflow.
English