Marking and Punch Marking - Course: Technique for Manual Working of Materials. Instruction Examples for Practical Vocational Training
 (introduction...) Introduction Instruction example 2.1. Door lock panel Instruction example 2.2. Holding Clamp Instruction example 2.3. Drill stand Instruction example 2.4. Angle gauge Instruction example 2.5. Bow for C clamp Instruction example 2.6. Open-end wrench 19/24 Instruction example 2.7. Base plate

### Instruction example 2.4. Angle gauge

To practise scribing of angular lines by means of protractor, based on datum edges.

Material

Sheet steel, bright
(approx. 380 MPa)
Thickness: approx. 2.5 mm
Width: approx. 40 mm
Length: approx. 70 mm
(Edges to be flat and at right angles to each other).

Figure

Hand tools

Smooth-cut file 200 mm (flat), caliper gauge, steel scriber, centre punch, engineers’ hammer.

Measuring and testing tools

Bevelled edge square, universal protractor

Accessories

Surface plate, scribing varnish, brush

Required previous knowledge

Reading of drawings, measuring, application of the mathematical law of the sum of interior angles (a + b + g = 180°), use of the universal protractor.

 Sequence of operations Comments 1. Arrange the working place, prepare the working materials. - Check for completeness. 2. Check for size and squareness of outer edges. Coat the surface with scribing varnish. 3. Scribe the hole centres with the caliper gauge and punch with centre punch. - Proceed step by step, based on the outer edges! 4. Scribe all angles, based on outer edges, by means of universal protractor (locate the try square and scribe with scriber from the punch mark outward).Example: angle 90.Bisector bisects 90° into two 45° angles forming 90° angle with outer edge, angle to be set on universal protractor, therefore: 45°.(45° + 90° + 45° = 180°). - Calculate the complementary angles by means of the law of the sum of interior angles I 5. Final inspection. - Dimensions and cleanness of scribing.

Completion

Drill the punched centres of angles with 1.5 mm diameter.

Saw out the angles. File to size and chamfer inner edges.

Mark angles. - Explanation:

 116 - 118° point angle of drill (normal material) 90° point angle of drill (hard material) 140° point angle of drill (soft material) 55° chisel edge angle of drill 60° wedge angle of chisel, prick-punch.

Drill 4 mm dia. hole at size 6 mm (punch mark on top)

Angle gauge