What is marking out in machining?
Scratching lines on a workpiece surface to indicate outlines or positions.
What is a datum in measurement?
A reference point, edge, or centre line for all dimensions.
How many datums are needed to position a point on a plane surface?
Two datums are required.
At what angle are two datums usually set to position a point?
They are usually at right angles to each other.
What is the purpose of a scriber on a metal surface?
To mark all lines on a metal surface.
Why must a scriber's point remain sharp?
To produce well-defined lines.
What is a divider used for in marking out?
To scribe circles or arcs and mark a series of lengths like hole centres.
From what materials is a divider made?
Tool steel or high-carbon steel.
What are the three types of punches?
Centre punch, dot punch, and prick punch.
What point angle does a centre punch have and its use?
A 90° point for wide, shallow hole-location marks.
What point angle does a dot punch have and its use?
A 60° point for witness marks.
What point angle does a prick punch have and its use?
A 30° point for light marks positioning dividers.
What is the first step in marking out the plate?
Find and scribe the centre line and centre-dot the relevant intersection.
How are arcs for hole centres and radii scribed on the plate?
Using dividers to scribe arcs for hole centres and radii.
Which tool is used to scribe tangential profile lines?
A precision steel rule is used to scribe tangential profile lines.
How is the centre of the small radius found?
By measuring from one end a distance equal to the radius plus 1 mm.
Why is an extra 1 mm added when finding the small radius centre?
To allow for the extra material left on the end.
How are dividers set when scribing the plate profile?
Using the graduations of a precision steel rule.
Where are dividers located before scribing each radius?
On centre dots before each radius is scribed.
What is a scribing block used for in testing?
It is used to scribe lines parallel to a datum surface.
How does a scribing block help set a job relative to a datum surface?
It sets the job parallel to the datum surface.
What alignment can a scribing block check on a job?
It checks job height and parallelism.
How does a scribing block assist with machine spindle alignment?
It sets a job concentric with the machine spindle.
What are the two forms of scribing blocks used in testing?
Fixed scribing block and universal scribing block.
What is the primary use of a hacksaw before filing?
To cut metal and remove large waste before final sizing.
What are the dimensions of a standard hacksaw blade?
300 mm long, 13 mm wide, and 0.65 mm thick.
What teeth counts are available for standard hacksaw blades per 25 mm?
14, 18, 24, or 32 teeth per 25 mm.
What factors determine the selection of a hacksaw blade?
Material hardness, section thickness, pitch, and blade material.
How does a single-cut file differ from a double-cut file?
Single-cut has one series of teeth; double-cut has two sets across its face.
Name three types of files used for different cutting tasks.
Flat, half-round, and round files.
What tasks do files like square, triangular, and needle perform?
Finishing, slotting, hole, groove, and angle-cutting tasks.
What is the safety rule for using a file?
Always use a handle installed on its tang.
What is the shape of the peen on a ball-peen hammer?
It is hemispherical.
How does a straight-peen hammer affect metal?
It spreads or draws metal in line with the handle.
How does a cross-peen hammer spread or draw metal?
At right angles to the handle.
What materials are used for the head of a soft hammer?
Lead, copper, babbitt, rawhide, wood, or plastic.
What is the primary use of a chisel?
To chip and cut metal and remove waste metal from a workpiece.
What must be inspected for hammer safety?
The handle and the head attachment.
What grip should be used when using a hammer safely?
A power grip.
What is a key safety rule for using a chisel?
Point the blade away from the body.
What is tapping in machining?
Tapping is cutting an internal thread.
Which tap has the longest chamfer lead?
The taper or first tap has the longest chamfer lead.
What is the tap drill size formula for a metric tap?
Tap drill size equals major diameter minus pitch in millimetres.
How is tap drill size calculated for an inch tap?
Tap drill size equals major diameter minus one divided by threads per inch.
What is the first step to tap a hole?
Drill the hole to the correct tap-drill size.
How should the tap be turned during tapping?
Turn clockwise while keeping the tap parallel to the hole.
What feature distinguishes an adjustable round split die?
It has an adjusting screw controlling thread diameter and fit.
What is the rule for turning the die during external threading?
Turn in quarter turns and back off in quarter turns to remove chips.
What materials are steel rulers made from?
Stainless steel or tool steel.
What do external calipers measure?
Outside dimensions.
What do internal calipers measure?
Inside dimensions.
Name three types of micrometers.
Blade, point, and disk micrometers.
What is the first step to read a micrometer?
Grip the frame.
What is the formula for micrometer reading?
Sleeve-scale reading plus thimble-scale reading times least count.
What does a vernier caliper measure?
External dimensions, internal dimensions, and depths.
How do you read a vernier caliper?
Add main-scale reading to vernier division times least count.
Metti alla prova le tue conoscenze con 24 domande su Workshop Hand Tools and Measurement.
1. What does marking out primarily achieve on a workpiece?
2. Which description best matches a datum in marking out?
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