This set of Engineering Metrology Quiz focuses on “Determine the Included Angle of an Internal Dovetail”.
1. Which of the following is not correct for dovetail joints?
a) Sloping sides act as a guide
b) The slope is 1:5 for softwoods
c) Used in box constructions
d) Difficult to make manually
Explanation: In dovetail joint, the sloping sides acts as guide and during the mating operation prevent the lifting of the female mating part. The slope is 1:6 for softwoods and 1:8 for hardwoods.
2. Which of the following statement is correct regarding the dovetail joint?
Statement 1: Angle between sloping face and imaginary centre plane is important.
Statement 2: It is difficult to pull apart the joint when glue is added.
a) F, F
b) F, T
c) T, F
d) T, T
Explanation: In case of dovetail the angle between sloping face and an imaginary vertical centre plane is important. The dovetail joints are very strong due to the shape of ‘tails’ and ‘pins’. This makes it difficult to pull the joint apart and it is nearly impossible when glue is added to the joint.
3. How many pins are used in the method of determination of an angle of a dovetail?
Explanation: To measure the angle of an internal dovetail, there is a need for two pins. These pins are of equal size. Along with the pins, slip gauges and micrometer is also used in this method.
4. What is the shape of tails and pins in an internal dovetail joint?
Explanation: The shape of tails and pins in dovetail joint is trapezoidal. A dovetail joint or simply is a joinery technique which is most commonly used in woodworking e.g. furniture, timber framing etc.
5. Which of the following is true about pins the method which is used to determine the included angle of an internal dovetail?
a) Pins touch both the sides of dovetail
b) Pins touches only one side of dovetail
c) Pins are of different size is used
d) Balls of different size is used
Explanation: In this method of checking the included angle of an internal dovetail, firstly the two pins are placed in the position such that touches both the sides of dovetail and then distance across the pins is measured.
6. Which of the following is not a name of dovetail joint?
a) Swallowtail joint
b) Fantail joint
c) Profile joint
d) Culvertail joint
Explanation: In Europe, dovetail joint is also known as swallowtail joint and a fantail joint. In pre dates history, dovetail joint is also called Culvertail joint. Profile joint is not the name of dovetail.
7. Which of the following formula is true for the angle of internal dovetail?
a) Tan A = (l2-l1/2) / h
b) Sin A/2 = (l2-l1/2) / h
c) Cos A = (l2-l1/2) / h
d) Sin A = (l2-l1/2) / h
Explanation: Formula for finding the angle of an internal dovetail is Tan A = (l2-l1/2) / h where l1 and l2 are the distance across the pins and h is the height of slip gauges. Thus by knowing these three parameters, angle A can be calculated.
8. Which of the following is used to measure the distance across the pins when included angle of the dovetail is determining by using pins?
c) Screw gauge
d) Slip gauge
Explanation: Micrometer is used to determine the distance across the pins. For setting pins at required height slip gauges are used.
Dovetail joints can be used in jet engines for attaching turbine blades to the shaft in jet engines and also for clockmaking, joining adjacent sections etc.
9. The method used for determining the angle of internal dovetail for some measurements. Which of the following is suitable for this method?
a) Angle of taper plug gauge
b) Any round taper work which can be placed on a surface
c) Any flat tapered work which can be placed on a surface
d) Angle of taper ring gauge
Explanation: This method is suitable to check angle of a plug gauge which is tapered and any round and flat tapered work which can be placed on a surface. Angle of taper ring gauge can be determined by the method of finding the angle of tapered hole by using balls.
10. Which of the following option is not true for the given statement about the method of determination of angle of internal dovetail by using pins?
Statement 1: Pins should extend above the top surface of a dovetail.
Statement 2: Pins are raised on slip gauges.
a) T, T
b) F, F
c) F, T
d) T, F
Explanation: The pins used in this method are raised on two sets of slip gauge blocks which are of equal heights. In this method one care should be taken that the pins do not extend above the dovetail’s top surface.
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