ENG 23 Exam 1

Visible/Feature (object) lines: Most important lines. Visible of what is being made.

Hidden (dashed) lines: Short narrow dashed line, represent a hidden feature.

Cutting plane lines: show where imagery cut has been made in order to view at a new angle. Arrows point to direction of cut.

— - —

Centerlines: shows the middle of symmetical parts.

Phantom lines: Shows that part moves and its other postion (not that important)

Break Line: long object that shows up as cut to same space.

Dimension Line: show length of object. They lie on the EXTENSION lines. They have arrows.

Extension Lines: these lay on visible lines extending out. Help to show where the DIMENSION line ends. (2-3mm gap between visible and start of extension SW will do auto).

Section Lines/Crosshatch Lines: Relate to cutting plane line. Shows the section that the plane cut. Think icing of cake shown.

Leader Lines: a straight line coming out to show an angle or radius. Has an arrow.

What projection view do engineers use when using solid works?

Orthographic: for example front, left, top and isometric(3-D of orthographic). NOT perspective

What is the most important view?

Front view: The front view should always have most info, just because it is the actual front doesn’t mean it is the front in SW.

What is the standard paper size for engineers?

B-size 11×17

Do we use third angle or first angle projection?

Third angle

Third Angle

First angle

Tolerance

The amount of error allowed for a specific part. (UPPER-LOWER), 0.040

Nominal Size

Describes the general size, 10 pm 0.02. The nominal is 10.

Allowance

The minimum clearance or maximum interference between two parts, the tightest fit.

Maximum Material Condition(MMC)

Contains the greatest amount of material, for HOLES this is the SMALLER value

Least Material Condition(LMC)

Contains the least amount of material

Clearance Fit

Assures clearance in both the MMC and LMC.

Interference Fit

Both the MMC and LMC don’t fit

Transition Fit

Comprise between the two, One is clearance and one is interference, one +, one -

Limit type

BAD, not best practice

Unilateral

only one side has a bound. So tolerance on this is .025.

Bilateral

what we are used to, tolerance is .02.

What are some other types of hole fits?

Sliding fit, free running medium drive

Which is preferred?

A, o25H8

Review and use chart

Define the 3 hole types.

A.THRU hole B.CounterBore C.Countersink

countersink hole

CounterBore hole

For clearance is the MMC or LMC the min. fit

MMC

flat head

Oval head

pan head

truss head

round head

Hex head

Hex washer, built in washer

Hex flange

slotted hex washer

button

socket cap

Phillips

slotted

combination, different than Phillips, this one is NOT symmetrical

Socket, Hex or Allen

one way

Square

Star

Hex Bolt: used in machinery and construction. Can be used with nut or tapped.

Wood Screw: used for word and soft materials

Sheet Metal Screw: sharp points, driven right into metal

Machine Screws: fully threaded, normal bolt

Socket Screws: are machine screws with internal hex socket, think Allen key

Lag Bolts: large wood screws, used for construction

Carriage bolts: smooth domed heads with square section underneath.

What is the ideal length of a screw?

2x the diameter of screw

0.25-20 UNC screw, what’s the pitch?

US units, so thread PER INCH, so 1/20 is pitch

M16-2 find the pitch?

Metric, so 2 is the pitch

Tip to tip measurement

Pitch

total end to end radius is called what on screws?

Major radius

from smallest trough to trough on screws

Minor radius

What does IPS stand for, also known as U.S units?

Inch Pound Second

If a hole goes through the whole feature what do you dimension it as?

THRU

What is the external class A, bolt or hole?

bolt

What is internal class B, hole or bolt?

Hole, think Bore, hole

What three major thread classes?

Class 1=loose, Class 2=standard normal, class 3=tightest fit, least tolerence.

When both limits are placed on a line, the lower limit goes second, T or F

True

what you put if a screw is left handed?

LH

Break lines are applied to represent an imaginary cut in an object T or F

True

Fine thread

smaller, more accurate

coarse thread bolts

less strong, quick to assemble.

A grade 5 nut has how many dash marks?

3

How many dashes does a grade 8 have?

6

what distance is for torque?

The perp distance, think pushing door, looping bar always 90 degrees.

How does a bolt come loose?

Transverse forces

Belleville washer

has divots so that the torque can be visually seen once washer pressed in

Zinc plated screws

Not expensive, moderate corrosion, blueish or yellow or normal color

Hot dipped galvanized bolts

thicker zinc coating, better for corrosion and better for outdoor use. Dull grey

Stainless steel bolts

more expensive but good at everything, corrosion strong etc.

Brass and bronze coated screws

good corrosion resistance, more expensive decorative applications , copper and gold color

Alloy steel bolts

highly hardened, basically no corrosion resistance but strong. Dark black