308A Fabrication Techniques 2

Question 1

What is a 'snap lock' seam used for in sheet metal fabrication?

Accepted Answer

Connecting round duct sections longitudinally with a self-locking seam that snaps together

Answer

A snap lock seam is a longitudinal seam used on round duct where one edge hooks over the other and snaps into a locked position. It provides a quick, secure connection without additional fasteners.

Question 2

When operating a power squaring shear, what safety device prevents the operator's hands from entering the cutting area?

Accepted Answer

A holddown or finger guard assembly

Answer

Power squaring shears are equipped with holddown mechanisms and finger guards that physically prevent hands from reaching the blade area during operation. These are critical safety devices.

Question 3

What is the purpose of a 'bar folder' in sheet metal fabrication?

Accepted Answer

To make narrow folds and hems on sheet metal edges for seams and safe edges

Answer

A bar folder creates narrow folds on the edges of sheet metal, typically for lock seams, hems, and edges. It produces consistent, uniform folds along the entire length of the metal edge.

Question 4

What is 'grooving' in sheet metal work?

Accepted Answer

Flattening and locking a grooved seam by closing the folded edges tightly together

Answer

Grooving is the process of closing and flattening a grooved (lock) seam using a hand groover or a grooving machine. It mechanically locks the folded edges tightly together.

Question 5

What is the correct sequence for fabricating a rectangular duct section?

Accepted Answer

Cut to size, form seam edges, notch corners, then bend to shape

Answer

The correct sequence is to cut the blank to size including seam allowances, form the seam edges (Pittsburgh pocket and lock), notch the corners, and then bend the blank into its rectangular shape.

Red Seal Sheet Metal 308A Practice Test

Red Seal Sheet Metal 308A Practice Test

308A Fabrication Techniques 2