State TWO advantages of cutting a taper on a lathe machine by using the compound slide method. FIGURE 5.2 below shows a taper with an included angle of 8°. Answer the questions that follow. Calculate the following: 5.2.1 The length of the taper 5.2.2 The set-over of the tailstock required to cut the taper 5.3 Calculate the following dimensions for a parallel key suitable for a 75 mm diameter shaft that must be used in the driveshaft of a crane: 5.3.1 Width 5.3.2 Thickness 5.3.3 Length State TWO disadvantages of down-cut milling.

NSC Mechanical Technology Fitting and Machining Screw cutting: State TWO advantages of cutting

State TWO advantages of cutting a taper on a lathe machine by using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2021 - Paper 1

Question 5

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State TWO advantages of cutting a taper on a lathe machine by using the compound slide method. FIGURE 5.2 below shows a taper with an included angle of 8°. Answer t... show full transcript

Worked Solution & Example Answer:State TWO advantages of cutting a taper on a lathe machine by using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2021 - Paper 1

Step 1

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

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Answer

Tapers with large angles can be cut easily, allowing for more versatility in machining.
The setup process is simple and quick, reducing downtime during operations.

Step 2

5.2.1 The length of the taper

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Answer

To find the length of the taper, we can use the formula involving the tangent of the angle:

ext{Length} \, (l) = \frac{D - d}{2 \times \tan \left(\frac{\theta}{2}\right)}

Inserting the values:

D = 92 mm (larger diameter)
d = 50 mm (smaller diameter)
( \theta = 8° )

Calculating gives us:

\tan \left(\frac{8}{2}\right) \approx 0.069926811

Thus,

2l = \frac{92 - 50}{0.069926811}

Solving for l yields:

\Longrightarrow l \approx 300.31 \, \text{mm}

Step 3

5.2.2 The set-over of the tailstock required to cut the taper

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Answer

The set-over can be calculated using the formula:

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

Here we take:

L = 425.3 mm (length)
D = 92 mm
d = 50 mm

Calculating gives:

\text{Set-over} \approx \frac{425.3(92 - 50)}{2} = 29.74 mm

Step 4

5.3.1 Width

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Answer

To find the width of the key suitable for a 75 mm diameter shaft:

\text{Width} = \frac{D}{4} = \frac{75}{4} = 18.75 \, \text{mm}

Step 5

5.3.2 Thickness

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Answer

For the thickness, we can use:

\text{Thickness} = \frac{D}{6} = \frac{75}{6} = 12.5 \, \text{mm}

Step 6

5.3.3 Length

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Answer

The length can be determined as follows:

\text{Length} = 1.5 \times \text{diameter of shaft} = 1.5 \times 75 = 112.5 \, \text{mm}

Step 7

State TWO disadvantages of down-cut milling.

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Answer

Vibration in the arbor is unavoidable, which can affect the quality of the cut.
The process can be time-consuming due to the fine feed that must be used.

State TWO advantages of cutting a taper on a lathe machine by using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2021 - Paper 1

Worked Solution & Example Answer:State TWO advantages of cutting a taper on a lathe machine by using the compound slide method - NSC Mechanical Technology Fitting and Machining - Question 5 - 2021 - Paper 1

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

5.2.1 The length of the taper

5.2.2 The set-over of the tailstock required to cut the taper

5.3.1 Width

5.3.2 Thickness

5.3.3 Length

State TWO disadvantages of down-cut milling.

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