5.1 State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method. 5.2 FIGURE 5.2 below shows a taper with an included angle of 12° which should be machined between two centres. Answer the questions that follow. 5.2.1 Calculate the length of the taper. 5.2.2 Calculate the set-over of the tailstock required to cut the taper in FIGURE 5.2 above. 5.3 Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: 5.3.1 Width 5.3.2 Thickness 5.3.3 Length 5.4 State TWO disadvantages of gang milling.

NSC Mechanical Technology Fitting and Machining Basic calculations on forces, moments and stress and strain: 5.1 State TWO disadvantages of c

5.1 State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2022 - Paper 1

Question 5

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5.1 State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method. 5.2 FIGURE 5.2 below shows a taper with an included angle of 12° ... show full transcript

Worked Solution & Example Answer:5.1 State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2022 - Paper 1

Step 1

State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method.

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Answer

The automatic feed of the machine cannot be used.
It causes fatigue in the operator.

Step 2

Calculate the length of the taper.

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Answer

To determine the length of the taper, we can use the tangent function:

an(\theta) = \frac{D - d}{2 \times l}

Here, the taper angle (\theta) is 12°, with (D = 72 , mm) and (d = 40 , mm). Substituting the values:

\tan(12°) = \frac{72 - 40}{2 \times l}

Calculating:

\tan(12°) = \frac{32}{2l}

This can be rearranged to find (l):

2l \tan(12°) = 32

Giving:

l = \frac{32}{2 \tan(12°)} \approx 152.23 \, mm

Step 3

Calculate the set-over of the tailstock required to cut the taper in FIGURE 5.2 above.

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Answer

The set-over can be calculated using the formula:

\text{Set-over} = \frac{L(D - d)}{2l}

Where (L = 70 , mm), (d = 40 , mm), (D = 72 , mm), and (l = 152.23 , mm). Substituting the values:

\text{Set-over} = \frac{(70 + 152.23)(72 - 40)}{2(152.23)}

Calculating, we find:

\text{Set-over} \approx 23.36 \, mm

Step 4

Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: Width

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Answer

The width of the parallel key can be calculated using:

\text{Width} = \frac{D}{4} = \frac{102}{4} = 25.50 \, mm

Step 5

Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: Thickness

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Answer

The thickness of the parallel key is given by:

\text{Thickness} = \frac{D}{6} = \frac{102}{6} \approx 17 \, mm

Step 6

Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: Length

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Answer

The length of the parallel key is determined by:

\text{Length} = 1.5 \times D = 1.5 \times 102 = 153 \, mm

Step 7

State TWO disadvantages of gang milling.

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Answer

The gang of cutters place more stress on the machine spindle bearings.
The cutters make the milling machine work harder.

5.1 State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2022 - Paper 1

Worked Solution & Example Answer:5.1 State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2022 - Paper 1

State TWO disadvantages of cutting a taper on a lathe machine using the compound slide method.

Calculate the length of the taper.

Calculate the set-over of the tailstock required to cut the taper in FIGURE 5.2 above.

Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: Width

Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: Thickness

Calculate the following dimensions for a parallel key suitable for a 102 mm diameter driveshaft: Length

State TWO disadvantages of gang milling.

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