ME272 Drawing Standard Class

Hey there everyone.

Welcome to our virtual lecture today.

Thank you for joining in and trying to

capture some of the things I would have wanted to tell you in person,

but due to COVID-related things,

I cannot be there right now.

Nevertheless,

welcome

to the class.

Objective for today is to better understand the engineering drawing standard.

This is going to be a part of the class from this time forward.

It will show up again and again and again and you're gonna need to know

how,

what

is required of you when making engineering drawings.

That's what we're trying to describe today.

But please,

be

aware that the things I'm describing to you right now are also on Learning Suite

under the content section,

and they are there for you to be able to

see basically everything we're gonna talk about right now.

But I'm just gonna talk through some of them

to help you.

Now,

also,

in section 5.7 of the guidebook where engineering part drawings are discussed,

this page,

the page you're seeing right here shows 28 standards.

22 of them are industry standards and 6 of them are company standards

and this concept is important to understand.

Please go look at this

and try to follow along with these standards and the pictures that follow them

where each of these standards are sort of discussed,

and

pointed out.

Though I'll tell you now,

this part of the guidebook will be way more understandable if you

stick with this video and watch it through to the end.

Plus speed it up and watch it as fast as you can,

OK?

All right,

the example used in this visual guide

is the clamp shown here,

which is a Bessey 6-inch clamp.

We

modeled this

and chose it specifically because it could be used to demonstrate all of the

engineering drawing standards,

OK?

Before we talk about the standards though,

super valuable for you to know that, "Above all,

drawings should be clear,

complete,

and unambiguous."

Now it's valuable to create drawings that are also pleasing to look at

and require the least amount of energy to be correctly understood,

and that's what the standard is all about.

OK?

But to understand the standard,

you're gonna need to know

the following words.

First of words you're gonna need to know are.

You're gonna need to know

what a Sheet Format is?

That's

basically the overall sheet size

and its format,

which is like these lines around the side,

OK?

And then the Title Block,

which is this thing down in the bottom right-hand corner.

All right,

what else are you gonna need to know?

You're gonna need to know that

these things in this area are called isometric,

excuse me,

called orthographic views.

These are orthographic projections.

In this area right up here,

these are our isometric views,

OK?

And then we have Auxiliary Views such as these,

but there are many kinds of auxiliary views.

This is called the Detail View.

The Detail View is being pointed out right in this area

with the A

and then it is zoomed into that area right in here,

and we can see what's going on.

But

there are also

Section Views,

Scales Views,

Cutaway Views,

all kinds of views can be done.

These are all called Auxiliary Views.

You need to know those

words as well.

All right,

other thing that's going on here is that there is an Assembly Drawing,

and there are Part Drawings.

Assembly drawings,

as shown on the left are a collection of a whole bunch of parts,

and a really important part of the assembly drawing

is the bill of materials or the parts list.

It is sometimes called,

and it's this thing that's right here.

And each one of these parts in the Parts List

refers to

another

CAD model.

And it has

its own drawing like what we see right over here.

So,

the Assembly Drawing is just the assembly

of all the pieces,

and then all the parts are separate

drawings.

OK,

they're controlled differently and so on and so forth,

they're separate drawings.

OK,

next piece.

Alright,

we just talked a second ago about the bill of materials or the parts list,

which is a list of all the parts and the quantity

of those parts in the assembly.

And then

in the Part Drawings and Assembly Drawings,

we have notes.

Those notes always appear directly above

the title block.

Another really important thing, in the title block is the title block tolerances.

The title block tolerances specify

how precise a part needs to be made,

and in our title block that we use for the class,

both inch and millimeter are specified in the same one,

and

this helps us to know the precision of the parts that need to be made.

All right.

Now,

a few more things you need to know before we even get into the standards,

some vocabulary,

this

is called a Dimension Line.

The dimension line has an arrow on the end of it,

and it always has a dimension in the middle of it.

An Extension Line is the thing that the arrow is pointing to,

and it always

comes close to but does not touch the part.

See,

like right there's a little visual gap,

OK.

We also have things that are called Detail Markers.

These are usually circles with a letter next to them,

but they can also be squares and other things,

but the default is a circle,

and that's called a Detail Marker.

In this case,

it's Detail A Marker.

OK,

then we also have Part Line.

The part line means that it is a line connected to the actual part,

the geometry.

Now,

in this image,

you can see that the Dimension Line,

this one,

and the Extension Line are somewhat gray.

And so, you can sort of tell the difference between a

Part Line and sort of an Annotation Line,

but

sometimes these both appear as black and sometimes have very similar line weights.

And

so,

it's,

if you follow the standards,

you can tell what the differences are between them,

but be aware that there is a Part Line and

then there are Dimension Lines and there are Extension Lines.

Now Leader Line is another kind of thing and it

is sort of like a dimension and an extension

line all put into one for arcs and circles,

OK?

We also have two more things going on here that we need to know,

and that's the Hidden Line.

The Hidden Line,

of course,

is the dashed line

that appears on things,

and then we have our center line.

And our center line is

or the center marker,

right,

this is probably better said as a center marker,

but that points to the center of the circle in this case.

All right.

And then,

here is the Center Line.

This is probably what we should have said before.

The other page was Center Marker.

This one is a Center Line.

The Center Line is a long,

short,

long,

short,

long,

short dash line.

And it represents the center of anything.

In this case,

it's the center between what we

would guess,

you know,

these two lines are equally

separated from that center line.

All right,

a few more things we gotta know in terms of understanding

our vocabulary.

OK.

This is a section view.

I know it's a section view because it has cross-hatched material.

That means if we sort of slice the product

right down this line,

that's right here,

whoa,

that's horrible,

and

then look in the direction of A,

A and A we will see

section A-A,

and this is section A-A.

It's being specified right there.

And anytime there's a cross-hatch,

that means we're looking at solid material,

and anytime there's no cross-hatch like in this hole,

we know we're looking at air,

OK,

which is exactly what's happening when you're,

you can look right down here at this,

OK?

There is a hole in the middle of that and so that's what we're seeing right there.

All right,

wow,

I can't really see what's going on.

Let me get rid of some of these,

let's

get rid of some of this.

OK,

what else do we have on here that we need to look at?

OK.

We

have already said that, that up at the top is the section view.

We have the section view title and scale.

OK,

the scale auto-populates in there.

OK.

And then what else do we have?

We have the Section Line and the Section Marker.

We've sort of already talked about those ones.

OK,

those were the

vocabulary that you need to know

as we start to get now into the

drawing standard.

I'm not going to read every word that's on these slides.

These

are in the style guide,

which

is

online for you to see for

the drawing standard under the graphical standards.

But

I will just step through them and try to make them clear for you.

All right?

So,

first of all,

all of the drawings you create in this class need to be made on B-sized drawing.

That's 11 by 17.

You'll never be asked to print,

so it's OK.

You're just going to turn in these digital ones at 11 by 17,

OK?

So please,

do not do them on a smaller sheet.

Do not do them in a portrait sheet.

Yes,

always do them in a

B-sized landscape

view.

All right,

all MeEn 272 drawings should use the provided MeEn 272 B-sized landscape sheet format.

And maybe we just ask ourselves why.

Actually,

we have taken a traditional

sheet format that you might find in industries such as this one,

and we have simplified it down to just the

core things that are important for this class.

It's the one we get right down here,

and it's actually easier for you

to not have to go seek a whole bunch of approvals,

but instead just have one person check your drawing,

and it's just easier,

easier,

easier to use the formats that we have given you.

Use the Getting Started Link in Learning Suite if

you haven't figured out yet how to do this.

All right,

hidden lines

should be shown in standard orthographic views of part drawings.

Let's see what this looks like.

OK?

Yes,

we should have hidden lines.

You can see all the hidden lines in these standard orthographic views.

These are really helpful for us to understand what's going on in the product,

and they're expected to be there.

All right,

hidden lines

should not be shown,

however,

if they're too busy.

All right,

and here we can see in this view down here all the hidden lines have been removed

because it's already super busy and what does it

look like when the hidden lines are there?

It looks like this

and it becomes virtually unusable.

So, in some cases you may choose to turn off

the Hidden Lines in a particular view if it is

obscuring the view and making it too, too busy.

All right,

hidden lines should not be shown on isometric

views nor on section views of part drawings.

All right,

so here we go.

Here's our isometric view.

We should not show hidden lines in this view.

Instead,

they should appear like this.

Why?

Because it's just too busy and too hard to

understand where those hidden lines are actually at.

Now in the cross-sectional views,

we also do not look at hidden lines.

So, this is what a cross-section view should look like.

It should not look like this one that's up here.

Why?

Because the section view is trying to show the detail at the section.

It doesn't want to show the detail everywhere else.

Hidden lines should not be shown in assembly

drawings, unless visual or technical clarity requires it.

So,

for example,

this is a pretty good view

of the

Bessey 6-inch clamp.

Here is a not-so-good view.

It is produced just extra information that isn't super useful

necessarily.

Now I think one exception for this might be in this region

where you want to sort of figure out

how far does a metal shaft go into this wooden handle,

but for the most part,

we do not put hidden lines on assembly drawings.

Views should be selected to minimize the number of hidden lines.

OK.

Let's just see how this works,

OK?

Here's the handle of the Bessey clamp.

In this particular view,

I have

a front view and I have a top view,

and then over here is a section view,

obviously,

and

by its orientation

up in this area,

there are all kinds of hidden lines.

But if I flip the whole thing around

and have my front view here,

and this is my top view,

now,

I have no hidden lines.

So,

we always want to choose the orientation of

views,

such that

the number of hidden lines is minimized.

All right,

the most descriptive view of the product should be chosen as the front view.

Why is this important?

Well,

first of all,

it's just natural.

So, this is all really good right up here.

This is what I deem to be the most descriptive view of the product,

not this.

OK,

this is not the most descriptive view of the product.

So,

we do not want

to choose this.

We want to choose the most descriptive view,

like this one

to be the front view.

That is the standard.

All right.

Isometric views of parts should be placed in the upper right area of the drawing.

Now this is a good time for me just to pause and say that in the

section of the guidebook there are two kinds of standards that are described.

One is the industry-wide standard.

One is the company-wide standard.

This one is not an industry-wide standard,

but it is the standard I want you to use in this class,

which is that the isometric view goes up into the top right view.

Not down here.

Not

off to the side over here,

not anywhere else,

want to have it right up in this area.

I'm liking it right up in that area because in the olden days when these kinds

of things used to be printed and there still are some people who print these,

this would be bound along this side,

and you would want to thumb through

the sheets without opening up each sheet to get a very

quick view of what it is. And having it in this area

with the title block also on the right side

helps to know what the drawing is all about with having to open up the entire sheet.

Views should not be shaded or rendered on any drawing.

OK,

this is also a company standard actually,

but

it is derived from the notion that

in

the olden days when drawings like this would be photocopied,

information

would become obscured

in these dark areas.

So, it's better,

just much better to not do that

and just have

no shaded views in there.

So, this is how we want it to be.

We don't want this,

we do want this.

All right,

each part must be fully dimensioned and no redundant

dimensions should be present in an engineering drawing.

So,

take a look at this one for a second,

see if you can see why

one of these is good and why one of these is not

good.

OK,

even I'm having a hard time with this one.

Let's see.

OK,

so that's the same on both drawings.

Oh yes,

OK,

we are missing

this one

is one that we want,

and it's not present over here,

so I don't know how to make this with

unless

I have it specified on the drawing.

So,

I need to have all my information there,

and then I do not want to have redundant information.

So,

this is redundant information,

as you can see in this area right here.

It's redundant because

1.05 plus 0.6 is equal to 1.65.

So, this dimension is redundant and should not be there,

or frankly,

any one of these.

This one could be redundant,

this one,

all three of these are redundant,

maybe is the way to say it.

For two dimensions that apply to the same dimension,

one should be indicated as a reference dimension with the parentheses or

with the notation "REF."

OK,

so

for example,

let's see if we can find this,

OK?

We

can,

whenever there's a parenthesis like this one,

it means it's a reference dimension.

It means there is a redundancy associated with this,

but it may be useful

for someone to know this dimension,

so they don't have to calculate it out

or

the word "REF" is typed in there.

Dimension lines should be placed so they are easily understood

and do not interfere with the part or assembly lines.

So,

let's see how we did here.

This one's looking pretty good.

This is the Cap that goes on the end of the

clamp,

so you don't mar up the wood or whatever soft material you're touching.

All of these

extension lines,

we're talking about extension lines.

I'm gonna go

extension lines for a second,

yeah.

So,

yes,

that's

good.

Let's look at the bad version of this,

OK?

Here,

the Leader Line is not clearly pointing to one feature for this,

so that's really bad.

And then over here

we have the Dimension Line,

which is the one with the arrow on it interfering with the Part Lines.

That's not good.

We don't like that.

We don't like that at all.

OK,

dimensions should not be placed on isometric views.

They should not be placed on isometric views because

we know that if we draw a circle

in an isometric view,

it's shown as an ellipse

in the isometric view.

And so,

if we try to dimension things in

an isometric view,

we are not

measuring their true size,

it's some other thing.

And in solid works,

if you try to do it,

it will tell you,

it will automatically put this word "TRUE" in front of it,

but I don't want you to ever do that.

It's

not good,

it's not part of the industry standard

to dimension

isometric views,

we never want to dimension isometric views.

All right,

dimensions should be placed as close to the part.

For successive dimensions,

they should be close to each other.

So, here's an example of this.

We

do not like this,

OK?

This is like, these parts,

these dimensions are so far away from the part it's uncomfortable,

just super uncomfortable to look at.

Instead,

we want to place them neat and tidy

and near each other

like this.

OK,

this is also a good time for me to just remind you that

I did not make up these standards.

These standards are ones that have been used for decades,

but they are good,

right?

They do help to make it so that every time you see an engineering drawing

in the future,

it will not feel as foreign as it does to you right now when you're learning.

Instead,

you start to see the common things again and again and again and

it will start to feel natural and be easier to read over time.

All right,

on to this next one then,

which is that dimensions should generally be placed between orthogonal views.

So, just take a look at what's going on here.

All of these dimensions are placed in between this view

and this view.

So, we call these two views orthogonal because they're 90-degree projections

of each other,

and the dimension is placed between them

as opposed to what's going on over here

where the dimensions are not placed between them.

The reason why this is valuable is that

if you just take a look at what's going on right here

in this area,

there are two hidden lines,

right?

If I want to know which

dimension

this,

you know,

which hidden line this dimension is applied to,

it's a little bit easier for me to do when that dimension has extension lines that are

going near this other view.

OK,

so can

I figure that out?

I don't know.

See,

this is the bottom of the cutout,

and this is the top of the fillet.

OK,

so this,

if I could draw a straight line,

which I don't know if I can,

but

basically that's what's going on there.

That's easier to tell than when I'm over here,

you know,

I get to the same line because I already know what it is now,

but

we want to sort of put those dimensions in between them,

it allows for the dimensions to be more shareable across the orthogonal

views.

Dimension lines should not cross,

and should not cross part lines or extension lines,

OK?

Yeah,

we don't want to have a bunch of lines crossing each other.

So, let's go look at what's going on here,

OK?

This one over here is obviously looking good.

OK.

I

have extension lines that are crossing each other and we'll see

maybe in a second,

I think there's a standard that says that that's OK,

at least I know that it's OK,

but we do not have dimension lines crossing each other.

Dimension lines,

the ones with arrows should never ever cross each other.

Nor should the ones with arrows be located on top of the part.

Here's located on top of the part.

Instead,

they need to be moved off of the part.

We also should not have dimension lines,

so this Leader Line is a Dimension Line for an arc,

and it is crossing

these,

these

extension lines,

and they should not be doing that.

How could all this be arranged?

Sometimes it's a little puzzle and you just got to do it until it works out,

and this one right over here is the one where we get that working out just right.

All right,

extension lines may cross,

but should not coincide with part lines.

This is what I was saying a minute ago,

is that the extension lines may cross each other.

Yeah,

let's see if we can find,

I

guess there's not

an awesome example of this.

We

saw that on the last one though,

but what we are seeing on this one

is that the extension line should not coincide with

the

part line.

So,

for example,

this line that's right in here,

that one,

OK,

and this one are colinear,

but they don't occupy the same space.

OK,

in this one down here,

they're occupying the same space.

They're literally on top of each other.

We do not want that to happen,

we want to have the extension line come off of the part,

not be on the part.

So, here we can see the Leader Line is on top of the Part Line.

We don't like that.

That's not

good.

It's not just we don't like it,

it's inconsistent with the standards.

Dimensions should be made to visible lines,

not hidden lines.

OK.

Here we are dimensioning what is going on here?

OK,

in this area,

we are dimensioning to actual lines that are not hidden

in these other areas that are orange,

we

are dimensioning to hidden lines,

which is

not appropriate.

It's wrong,

OK?

Now,

this one,

we are coming right down and measuring on,

we're measuring

to

the actual part lines,

but frankly,

these arrows should not be

on top of the part,

they need to be pulled off somewhere else.

It is,

however,

hard to know where we would pull them off to,

because if we pull them off,

we're gonna end up with line just underneath this one and just underneath this one,

and it's going to start to become less clear

what that dimension is pointing to.

If we have the dimension come off to here

like this,

this might be in a more appropriate place to have it,

but

we would not want to do it at the same time we're trying

to do these because that's gonna get too complicated in that space.

So, this is where we remember our original

goal which is that above all engineering drawings should be clear

and concise and correct.

And in this case,

this may be one reason

to

go with this

even though it's technically a violation.

Dimensions

should be placed in views where the feature has its true shape,

and is most clearly shown.

So,

for example,

here on the diameter of this outside circle that's right over here,

we want to dimension it where it appears as a circle.

We do not want to dimension it where it does not appear as a circle.

That's to help make it extra clear.

Angular dimensions should point to extension lines,

not to feature lines.

OK.

In other words,

it should look like this.

OK,

right up here at the top.

I've got an extension line off this face,

an extension line off of here,

and I've got a dimension in between it.

Over here,

I am pointing to part lines,

not to extension lines or in this case the

extension lines are coinciding with the part lines,

which

is not good.

Sometimes, it can be hard to know how to do this if not doing it this way,

but nevertheless,

this is a violation of the standard.

Holes

should be dimensioned in views where they appear as circles.

They should use the diameter symbol before the

dimension or the notation "DIA" after the dimension,

and the location dimension should come from the centerline of the circle.

OK,

so

this is appropriate.

This is appropriate.

OK,

these ones here are also appropriate,

even though I'm on my

no-thing,

OK.

But

what's not good here,

OK?

So, first of all,

we are dimensioning to the center of the circle,

which is good.

Here we are attempting to measure to the side of the circle,

not good.

Why do we do

that?

Largely because holes are put in with drills and the center of the drill is known,

really not the edge of the drill.

So, we want to go place

it based on the center.

All

right,

that's

that.

OK,

when there are multiple identical features,

dimension only one feature

and indicate the number of features to which the dimension applies by,

for example,

"6X" preceding the dimension.

OK,

let's go see what we got here.

OK.

Well,

first of all,

look,

I got this one,

which is good.

OK,

that refers to this,

this,

this,

and this.

But

there's some things here that are not good,

OK?

That's this one,

this one,

this one,

and look at this super messy one

right down in here,

right?

We do not want to do that.

Let's just simplify the thing

and

just go get ourselves

4X

R.1,

OK?

That's a lot better,

a lot better than what we had otherwise.

Rounds

and fillets should be dimensioned by radius,

not by length or

diameter.

So,

for example,

these

radii

are all shown as R.13, that means it's a radius.

We do

not do this.

We only dimension with diameter symbol when it is a full circle.

When is an arc or something else,

is dimensioned with a radius.

it

This is the standard.

OK.

What are we looking at now?

Oh,

this is the same thing,

right?

We do not try to dimension

radii

with

linear dimensions.

We use an arc command,

you know,

like a radius command.

All right,

in dimensions,

excuse me,

chamfers may

be dimensioned by horizontal and vertical distances,

or

by horizontal dimension and an angle.

All right,

see if we got an example of that on here anywhere.

OK,

so here's one,

OK,

right up here.

That's acceptable.

This is acceptable,

and this

one I'm circling right now is the most common way to do it.

OK,

a horizontal dimension,

so this dimension,

plus the angle.

Use

the proper number of significant digits for the desired implicit tolerance.

This is

really important and something that many of you will overlook

if you're not careful about it and thinking about it.

OK,

so,

take a look at what we have going on right here,

which is the length of this clamp,

the length of the bar of this clamp.

OK,

it is listed as 10.2 inches.

Now,

there is a tolerance associated with this,

and it comes straight from the title block tolerance,

OK,

which we find right down here,

and we can see that when we are one decimal spot in,

then it is going to be plus or minus 20,000 of an inch.

OK,

so this over here is plus,

minus,

I don't know why I'm trying to write this,

0.02 inches.

That's horrible.

It's really hard to do that with my trackpad.

All right,

that just looks so stupid.

Anyway,

that

is telling us the tolerance of that.

Now,

the default tolerance

for solid works

is this number.

It is,

excuse me,

2 decimal

spots,

2 digits past the decimal spot.

So,

this would mean if we were to leave it that way,

that we need

this to be plus or minus 10,000 of an inch.

And so, you need to go in and you need to adjust

the number of significant digits for

the tolerance that you need.

All right,

that is all we're gonna go over today.

That's been 30 minutes,

and those are the

drawing standards.

You're gonna need to stick with them

and

you're gonna need to understand them,

and I've just given you a bunch of yes/noes,

yes/noes,

yes noes to try to help you visualize

the difference between it being done right

and it not being done right.

OK.

Good luck.

Tie this to what you're reading in Section 5.7

of the guidebook.

You

do this,

you spend some time now learning it and it will stick with you,

and it's gonna serve you well as you

work all the engineering drawings for all the projects

that will be turned in for this class.

OK,

thanks everyone.