Answers

(Theory)

1       (c)     Bench grinder

          (b)     Bench drill

          (a)     Pedestal grinder

          (d)     Column drill.

 

2       Any one of the following:

          •        they don’t require a bench or stand

          •        larger jobs can be positioned under a column drill

          •        can usually take larger drill bits

          •        provision for clamping on the base.

 

3          One of the most likely times for a grinding wheel to “explode” (crack and fall apart) is during the start up stage where the wheel is not rotating at the recommended speed. Standing to the side of the grinder during this stage improves your chances of not being hit by flying parts of the wheel.

4 Manufacturers of metal cutting tools recommend cutting speeds for different materials which, when followed, will enhance good production and tool life. It is necessary to convert cutting speeds into revolutions per minute for a given drill size. These revolutions per minute are the speed the drill should run at.

5      

6          Portable drilling machines are used because they can betaken to the job when it is impractical to take the job to the drill.

7       Any two of the following:

          •        bench drill

          •        column drill

          •        radial arm drill.

8       You tell which power source a portable power tool uses by looking at the power connection lead.

9       A “nibbler” removes the largest amount of material in its cutting action.

10     “Shears” remove the lease amount of material in the cutting process.

11     “Shears” are the portable power cutting tool most likely to cause distortion.

12     A “jigsaw” is the tool which can cut through the thickest material.

13     An “angle grinder” is the portable grinder most suited for use as a cut-off machine.

14     A “die grinder” is the portable grinder used for delicate operations.

15     The point of a scriber overheated during grinding will either increase or lose its hardness making it useless.

16     The recommended gap between the work rest and grinding wheel is 1 - 2 mm.

17        A glazed grinding wheel is where the “abrasive grains are blunt”.

18     Truing a grinding wheel involves “correcting any out-of-roundness of the wheel on the machine”.

19     The purpose of a pilot hole is to ease the load on a larger diameter drill and to ease the load on the machine when the large drill is being used.

20     This fault can be corrected by chipping a groove with a round nose chisel on the side towards which the drill is to move. The cutting force can now push the drill over into the groove and back onto centre.

          It may be necessary to repeat the procedure several times before the drill is properly located. It may also be necessary to make a small adjustment to the position of the work in relation to the drill to ensure proper alignment.

          This correction procedure should be commenced when the drill has entered about half way down the point. It must be completed before the body of the drill enters with workpiece, because once the drill is cutting to its full diameter it is not possible to make any further corrections.

21     Any one of the following:

          •        holes to be drilled slightly out of square

          •        clamps to not hold jobs securely.

22     Any portable power tool should be checked for faults so it is not in a dangerous condition when it is used.

23        Any one of the following:

          •        the size/capacity required for the job

          •        the job that has to be done, e.g. drilling or cutting or sawing

          •        the available power source.

(Practical)

Job PT8:Tool Re-Sharpening

Practical Checklist

The following checklist is used to assess this practical exercise. For the job to be passed it must warrant a tick for each feature.

   

ü or ´

Centre Punch

Angle 90°

 
 

Uniform grind marks

 
 

Not overheated

 

Scriber

Point

 
 

Uniform grind marks

 
 

Not overheated

 

Chisel

Angle 65°

 
 

Uniform grind marks

 
 

Not overheated

 

General

No burrs

 
 

No sharp edges

 
 

Tools stored properly

 

Job PT 9: Off Hand Grinding And Drilling

Practical Checklist

The following check list is used to assess the practical exercise. For the job to pass it must warrant a tick (ü) for every feature.

     

ü or ´

Block

Hole 1

Position, size, deburred, not overheated

 
 

Hole 2

Position, size, deburred, not overheated

 
 

Chamfers

Size, angle deburred, not overheated

 

Sheet Metal

Hole 1

Position, size, deburred, not overheated

 
 

Hole 2

Position, size, deburred, not overheated

 
 

Cut out

Position, size, deburred

 
 

Overall

Size, deburred

 

General

Matching

6 mm bolts and nuts can be used to clamp parts together

 
   

Sheet metal component matches chamfered size of block

 
 

Finish

Tools cleaned and stored properly

 

Safety

Workplace safety standards maintained

 

Job Plan

Logical sequence

 
 

Thorough