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Cutting Sheet: Shear, Snips and a Clean Edge

A squaring shear gives straight, square blanks. Snips cut curves. Whatever you use, the edge is not finished until the burrs and nicks are gone, because that edge is where a crack can start.

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The drawing

Where to buy
Section of a squaring shear with blade, bed and backstop, aviation snip handle colours, and a parts list
After FAA-H-8083-31B pp. 4-9, 4-12, 4-13 (Figs. 4-23, 4-35). Typical only.

Step by step

StepActionWhat to do
1Mark the cutSee sheet layout.
2Choose the toolSquaring shear for straights; straight snips for aluminium up to 1/16 in; aviation snips for holes, curves, round patches and doublers.
3Line up on the shearCutting line even with the cutting edge of the bed.
4Square a sheetSquare one end with the fence, then hold that end against the fence for each other edge.
5Several the same?Use the backstop behind the cutting edge.
6CutHold the sheet securely and step on the treadle. Keep hands clear of the blade.
7Finish the edgeFile or burr. See deburring.

Tools you need

ToolWhat forBuying guideCatalog
Aviation snipsCurves and patchesShears3-piece set
NibblerInside cutsShearsHand nibbler
Files and burring toolEdge finishDeburring toolsEdge tool

Which snips

HandleCuts
YellowStraight
GreenCurves right
RedCurves left

FAA-H-8083-31B p. 4-13.

Three aviation snips with coloured handles
Handle colour tells the cut direction. FAA-H-8083-31B, Fig. 4-35

What to check when it is done

Look atGoodIf not
SizeTo the drawingRecut
SquareCorners 90°Square again on the fence
EdgeSmooth, no nicks or tearsFile or burr; discard if cracked

Questions people actually ask

What do aviation snip colours mean?

Yellow cuts straight, green curves right, red curves left.

Limits of this guide

What the sources support, and no further.

  • The manual governs. Where the SRM, the drawing or the fastener maker says otherwise, follow them; this page explains general practice.
  • Sizes of shear and capacity are on the machine plate.

Where to buy

AmericaDistributor coming soonOur partner for this region is on its way
EuropeDistributor coming soonOur partner for this region is on its way
OceaniaDistributor coming soonOur partner for this region is on its way

Distributors coming soon.

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Calculators

CalculatorBlanks per SheetBlanks from a sheet.CalculatorSheet weightWeight of the stock.

Guides

ChartAluminium gaugeThickness.

How to do it

Standard practiceSheet layoutHow to lay out an aircraft sheet

Tools

Tool guideHand and pneumatic shearsHow to cut aircraft sheet metalBuying guideSheet Metal Shears: Snips, Throatless Shears and NotchersWhat to buy.

Data sheets

Data sheetCrescent Wiss M123R — aviation snips M1R, M2R, M3R and the M123R setCrescent Wiss M123R Crescent Wiss compound action aviation snipsData sheetRoper Whitney No. 141 — portable hand notcherRoper Whitney No

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Sources

Educational reference only. not approved data. Always consult the applicable SRM, AMM, or AC 43.13-1B and your certifying authority.
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