Sheet 01 of 12

Sheet Metal Rules Explained (Thickness, Radius, K-Factor)

Q: Where do you set the sheet thickness?

In the sheet metal rule. Every sheet part takes its thickness from its rule, so changing the rule changes them all.

Q: What does a larger K-factor do to the flat length?

Makes it longer. The neutral line sits further out in the bend, so more material goes round it.

Q: By default, where does a flange's bend radius come from?

The rule. The rule gives the bend radius unless you change it in the flange.

In 5 minutes you'll set up a sheet metal rule and see exactly how thickness, bend radius and K-factor change the flat length of a bent part.

Part: Sheet Metal Rules
Rule: Steel 2mm
Sheet: t 2 · R 2 · K 0.4
Time: 5 min
Status: Open

OP 10Watch
OP 20Turn the part
OP 30Build
OP 40Inspect
OP 50Quiz

OP 10Watch

Video in productionBuild along with the steps in OP 30 meanwhile.

Chapters

00:00What a rule is
00:40Make a rule
01:40First bent part
02:40Change the K-factor, watch the flat length
03:50Common mistake
04:20Your exercise

OP 20Turn the part

Drag to turn, scroll or pinch to zoom. Flat shows the blank before it is bent: the same sheet, the same frame.

OP 30Build it in SolidCraft

Your task

Make this bracket in SolidCraft 0.21:

A sheet metal rule called Steel 2mm: thickness 2 mm, bend radius 2 mm, K-factor 0.4. Make it the active rule.
A sketch on the XY plane with a 100 × 60 mm rectangle, corner at the origin. Finish the sketch.
Flange on that sketch: this makes the flat base.
Flange again on the long front edge: height 30 mm, angle 90°.
Click Flat Pattern (Sheet Metal tab › Flat) and write down the flat size.

Then change only the rule's K-factor to 0.33 and look at the flat pattern again.

What to write down

The flat length across the bend with K-factor 0.4.
The same length with K-factor 0.33.

Type both below and press Check. The other side of the flat pattern is 100 mm in both cases: the bend runs along it.

OP 40Inspect

Enter what SolidCraft shows you. Each value is checked against SolidCraft's own result, within the tolerance shown. Nothing you type leaves this page.

Flat length across the bend, K-factor 0.4 ± 0.05 mm mm

Flat length across the bend, K-factor 0.33 ± 0.05 mm mm

Show the drawing and bend table

exercise · Steel 2mm · t 2 · R 2 · K 0.4

Flat blank 100.000 × 86.398 mm · 1 bend

Bend	Angle	Dir.	R mm	Length mm	Allowance mm
1	90°	up	2	100	4.398

exercise.solidcraft exercise.json

exercise-k033 · Steel 2mm · t 2 · R 2 · K 0.33

Flat blank 100.000 × 86.178 mm · 1 bend

Bend	Angle	Dir.	R mm	Length mm	Allowance mm
1	90°	up	2	100	4.178

exercise-k033.solidcraft exercise-k033.json

OP 50Quiz

Q1Where do you set the sheet thickness?

Q2What does a larger K-factor do to the flat length?

Q3By default, where does a flange's bend radius come from?