1.4 Fasteners and fittings

Question 1

What are the 8 fasteners and fittings

Answer 1

Solid riveting, pop riveting, self tapping screws, wood screws, machine screws, nuts and bolts, coach bolts, KD fittings

Question 2

What is the adv of pop riveting over solid riveting

Answer 2

Pop riveting is quick and only requires access from one side of the pieces to be joined.

Question 2

What is the process for solid riveting

Answer 2

A solid rivet , made from malleable metal, is inserted into aligned holes between the 2 pieces of metal. The pieces of metal are pushed together and then the tail of the rivet is hammered to squeeze and hold the pieces together.

Question 3

What do self tapping screws need

Answer 3

Self tapping screws require a pilot hole which is approximately the same diameter as the core diameter of the screw

Question 3

What 2 fasteners and fittings are permenant

Answer 3

Pop and solid riveting

Question 4

What is the process for pop riveting

Answer 4

A hollow aluminum rivet, with a steel pin, is used to join thin sheet metal pieces together. The rivet and pin are placed into aligned holes in both pieces, then a pop rivet gun is inserted over the pin and the trigger is pulled. This action pulls on the pin which crushes the rear face of the rivet to hold the pieces together. The join is completed when a steel pin snaps at a designated point.

Question 5

What fastener and or fitting could be used to make washing machine panels and computer cases, or polymer parts e.g. securing a battery compartment on a child’s electronic toy

Answer 5

Self tapping screws

Question 5

What is the use of self tapping screws

Answer 5

Self-tapping screws are a temporary means to join thin sheet metal

Question 6

What is the process for wood screws

Answer 6

A clearance hole, larger than the often unthreaded shank, is drilled into the top piece of timber for the screw to pass through. A pilot hole, approximately the same size as the core diameter, is drilled into the bottom piece of timber to guide the screw in cutting a thread into the wood.

Question 7

What is an adv of wood screws

Answer 7

They have a countersunk head- flush fitting

Question 8

What are the 3 head types and properties for wood screws

Answer 8

-Slot head - simple but not suitable for a power screwdriver as the blade can slide out of the slot
-Phillips- increased contact and more torque
-Pozidriv - even greater contact through additional slots and hence more torque e.g. power screwdrivers

Question 9

What is the use of machine screws

Answer 9

Machine screws are a temporary means to join thicker pieces of metal together

Question 10

What fasteners and or fittings could be used for covers on a motor or gear housing

Answer 10

Machine screws

Question 11

What is the property and requirement for machine screws

Answer 11

-Threaded shaft
-Clearance hole in top piece and threaded bottom piece

Question 12

What are the 2 different washers

Answer 12

Plain flat, Spring/split lock

Question 13

What is the adv of a nyloc nut

Answer 13

Nyloc nuts have a soft insert that deforms around the threaded bolt and helps prevent the nut coming undone due to movement

Question 14

How do bolts work

Answer 14

Bolts are similar to machine screws but are put all the way through both pieces of metal with a nut tightened onto the other end of the bolt to keep the pieces together.

Question 15

What is the adv of coach bolts

Answer 15

Can only be undone from the nut side which mean fitting to an outside door can be made secure

Question 15

What is the adv of plain flat washers and spring/split washers

Answer 15

Plain flat washers help spread the tightening force under the head of the bolt and stop the digging into the metals surface

Spring/Split lock washers keep tension on the joint to prevent it coming undone due to movement

Question 16

What is the use and properties of coach bolts

Answer 16

Coach bolts are a temporary means to join pieces of timber together. They have a square profile under the domed head which digs into the wood when the nut is tightened. This prevents the bolt from rotating.

Question 17

What is the use of KD fittings

Answer 17

Knock Down fittings are used to assemble flat-pack furniture. Wooden dowels may also be used to locate panels prior to securing with a KD fitting

Question 18

How do polymer modesty blocks work and what is its disadv

Answer 18

Polymer modesty blocks to join panels at 90 degrees. Unattractive and not very strong joining method

Question 19

What are the 3 KD fittings

Answer 19

Polymer modesty blocks, Barrel nut and bolt or cross dowel fittings , Cam-lock connections

Question 20

How do Barrel nut and bolt or cross dowel fittings work and what is its adv

Answer 20

Barrel nut and bolt or cross dowel fittings use metal fittings that give a strong joint with flush fittings

Question 21

How does Cam-lock connections work

Answer 21

Cam-lock connections combine a fixed screw with a head that locates in a disk. The disk is turned with a screwdriver blade and, because the screwdriver head is off-centre, the screw is put under tension and the joint made secure