Unit 04 · Lecture 8
Sheet metal bracket
Sheet metal parts are modelled differently. You don’t extrude to a depth. You start from a face of fixed thickness and fold flanges from it, much as the part is made in a workshop.
Video 17:48Reading 9 minUpdated 26 October 2026
What you will build
A 35 × 30 mm bracket in 0.5 mm steel with two full-length 12 mm flanges, a centred 20 mm back flange with a double hem, a 10 × 4 mm cut-out with two Ø2 holes, four Ø3 holes and R3 corner rounds, plus its flat pattern.
You will learn
- The Sheet Metal (DIN).ipt template and Sheet Metal Rules
- Face and Flange, including width and position options
- Measure to check inner dimensions
- Unfold, cut and Refold
- Hole, Corner Round, Hem and Flat Pattern
Before you start
You should be comfortable with sketches and constraints from Unit 02.
Step by step
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01
Start from the sheet metal template
0:41Choose Sheet Metal (DIN).ipt instead of the standard part template. The window opens on the Sheet Metal tab. Sketch a 35 × 30 mm Two Point Center rectangle in the top view.
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02
Create a Face, not an extrusion
1:21Everything in a sheet metal part follows the material thickness, so instead of Extrude use Face. Its output shows the SM Rule. Open Sheet Metal Defaults to see the rule Default (mm) with a 0.5 mm thickness. Material, thickness, unfold rules and miter, rip and seam gaps all come from this rule.
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03
Add the side flanges
3:26Open Flange and pick the top edge. Set the distance to 12 mm at 90°, and flip the direction if needed. Distance is measured from the intersection of the two outer faces. Select both long edges to make both flanges at once.
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04
Check with Measure, then fix the position
4:54Use Tools → Measure between the inner faces of the flanges. It reads 34 mm but the drawing needs 35. Edit Flange1 and change the position from outer face through the plane to inner face through the plane. That adds 0.5 mm on each side.
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05
Add a centred back flange
6:21Add a flange on the back edge. Under Edge Sets → Width, choose Centered and enter 20 mm, with a 12 mm height. This one sits outside the face on the drawing, so use outer face through the plane. The relief gaps equal the sheet thickness.
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06
Unfold, cut and refold
8:31The cut-out is easier to draw flat. Use Unfold, choose the first face as the stationary reference and add all bends. Sketch a 10 × 4 mm Two Point rectangle centred with a vertical constraint, plus two Ø2 holes 3 mm below it and 10 mm apart. Use Cut, then Refold with the same reference.
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07
Place holes without a sketch
12:02Open Hole with centre point creation on. On the side flange, place Ø3 holes 6 mm from the top and 10 mm and 20 mm from the front edge. Termination Through All cuts both flanges at once.
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08
Corner round, hem and flat pattern
14:18Corner Round is the sheet metal fillet. Apply R3 to the flange corners. Then use Hem on the back flange, type Double, with a gap of 1 × thickness (0.5) and a length of 5 × thickness (2.5). Set the material to steel and the appearance to steel polished, and create the Flat Pattern.
Why sheet metal is different
Rules drive everything
Thickness, bend radius and unfold behaviour are properties of the material and its rule, not of individual features. Change the rule and every flange, hem and flat pattern updates together.
The flat pattern goes to manufacturing
Sheet parts are cut flat, then bent. The flat pattern gives the shop the blank outline, bend lines and bend data. The folded model and flat pattern live in the same file, and the drawings unit uses both.
Common mistakes
- Starting from Standard (DIN).ipt, which has no sheet metal tools.
- Not checking inner dimensions, which leaves flanges 1 mm off.
- Sketching cut-outs across bends in the folded state. Unfold first.
- Typing hem values by hand instead of as multiples of thickness, which breaks when the thickness changes.
Practice exercise
Change the sheet thickness to 1 mm in Sheet Metal Defaults. Watch the hem and flanges update, and re-measure the inner width.
Check yourself
What replaces Extrude as the first sheet metal feature?
Face.
Inner width measures 34 instead of 35. What do you change?
The flange position, to inner face through the plane.
Which feature folds an edge back over itself?
Hem.
What do you hand to the manufacturer?
The flat pattern.
Want the graded version? Take the 5-question lesson quiz in the course player after the video.
Written by the CADsmit instructor from the lecture recording and checked in Autodesk Inventor Professional 2027. Last updated 26 October 2026. Spotted an error? Tell us.