Cover Image
close this bookStraightening - Course: Technique of Working Sheet Metals, Pipes and Sections. Instruction Examples for Practical Vocational Training
View the document(introduction...)
View the documentPreliminary Remarks
View the documentInstruction Example 15.1. Bendings and Bucklings
View the documentInstruction Example 15.2. Twistings
View the documentInstruction Example 15.3. Bent Angle Section
View the documentInstruction Example 15.4. Bent Pipe
View the documentInstruction Example 15.5. Dented and Corrugated Metal Sheets

Instruction Example 15.2. Twistings

Practise the straightening of twisted flat material and square sections by means of moving irons and tap wrenches.



- Flat material (380 MPa) (l)

thickness: 5 mm

width: 30 mm

length: 250 mm

- Square section (380 MPa) (2)

thickness: 10 mm

length: 250 mm


Moving iron, tap wrench, locksmith's hammer

Measuring and testing means

Surface plate, workshop ruler, steel rule

Auxiliary means


Required previous knowledge

Manual material working: testing, hammering

Sequence of operations


1. Prepare the working place; make available the working material.

- Check for completeness.

2. Clamp the twisted flat material laterally in the vice - the twisted end must project.

- Part (1)

3. Undo the torsion with the help of the moving beginning directly at the vice; in doing so, the moving iron is shifted step by step in outward direction.

- Consider the elastic recovery when turning backwards.

4. Take the flat material out of the vice and rework it by hammering on the straightening plate if it is not even enough.

- Strike even hammer blows towards the end.

5. Check evenness of the material on the surface plate or by the workshop ruler.

6. Clamp the distorted square section laterally in the vice - the twisted end must project.

- Part (2)

7. Apply an appropriate tap wrench to the beginning of the twisting and move it in the opposite direction of the twisting.

- When turning backwards, do not bend the square section to the side.

- Consider the elastic recovery.

8. Check evenness on the surface plate or by means of workshop ruler.