Instruction example 4.5. Steel square

To practise straight long sawing cuts of high precision on sheet steel.

Material

Sheet steel (higher-strength or hardenable steel)
Thickness: 5 mm
Width: 80 mm
Length: 120 mm

Figure

Hand tools

Steel scriber, prick punch, engineers’ hammer, 4 mm dia. drill, hand hacksaw (saw blade of normal tooth pitch), smooth-cut file 250 mm (flat).

Measuring and testing tools

Steel measuring tool, try square.

Accessories

Vice, surface plate, copper sulphate solution, cutting oil.

Required previous knowledge

Reading of drawings, measuring and testing, scribing and prick-punching.

Sequence of operations	Comments
1. Arrange the working place, prepare the working materials.	- Check for completeness.
2. File steel sheet at one longitudinal side and one end side flat and at right angle to each other to serve as datum edges.
3. Coat sheet with copper sulphate solution, after drying scribe inside edges and provide with check punch marks.	- Danger! Copper sulphate solution is toxical!
4. Prick-punch point of intersection of inside edges and drill with 4 mm dia. drill, remove burrs.	- 1400 r.p.m. speed Drill under supervision of instructor only!
5. Clamp sheet in vice so as to permit vertical sawing cut. At a distance of 1 mm to the scribed line saw out inside edges first and then end faces of the workpiece.	- Provide saw blade with cutting oil.
6. Final inspection.	- Dimensions and straightness of cut.

Completion

Produce final form by filing, check with bevelled edge square, have inside and outside edges hardened.

Steel square