>> This is a tutorial for part A of lab 3.
This is the geometry we're going to create.
We start with a new file that is in metric then we create,
start by creating a circle at the origin, center is zero,
zero and radius is 20 and then creating another circle the same
center of radius 40, and then finally create another circle
at 0,75, seventy-five, also radius 20.
Let's pan this towards the center and zoom
in a little bit using our scroll in our mouse.
Then we're going to create 2 circles
but this time it's using tangent tangent radius
because the circle we're looking for is tangent to this circle,
tangent to this larger circle and then radius of 100.
Okay, repeat the same thing, you need to click
on the approximate location of the points of tangency
so circle, tangent, tangent, radius.
Okay, and then radius is 100.
Next thing we're going to do is we're going
to start trimming things that we don't need, okay?
Using this circle up here, the small one on top and this
on the bottom as our boundaries, press enter.
Click this part of the 2 big circles that we want to trim out
and then we repeat that trim command again.
This time our boundaries are the 2 arcs of radius 100,
press enter, and click on this part of the 2 other circles
that we want to trim away.
The next thing we're going
to do is we're going to create a key way.
Let's zoom in on the location of the key way.
I'm going to first construct a vertical construction line
passing through the center and to make sure
that it's vertical I'm going to use the ortho.
Ortho means you can only go vertical or horizontal.
So that line is perfectly vertical and then I'm going
to offset that construction line,
the length is not important, 5 units to the left
and 5 units to the right, okay?
And then I'm going to create a line from this intersection
to this intersection because that line I can now offset
at a distance of 5 as well so that tiny little line,
select that line to offset above it,
that's the upper part of the key way.
Now, all we have to do is clean it up by trimming.
So let's trim.
Using this horizontal line and this horizontal line
as our cutting edges, press enter,
and then trim away the parts of the vertical lines
that we don't need in the picture.
And then we need to do another trim,
this time with the 2 vertical sides
of the key way as our cutting edges.
Press enter in between and then click on the part of the circle
that we want to trim away
and then we just delete this little line here
and the construction line, the vertical construction line
and there is our key way.
Next thing we need to do is to convert this into a block
by going to insert and then create block, okay?
Let's select points to be included in the block.
All we're doing is we're trying to create a single entity
that combines everything here
into a single object called a block and it's asking
for a name of the block.
We type cam and then we select a base point, just say pick point,
and then we want the base point of this block
to be center of the circles, which is also the origin, and then we're done.
All it did, now everything here is now 1 entity or 1 block
and it's called a cam.
Very similar to polyline.
Next thing we do is to create a circle above the cam.
So create, go back home and create circle, center radius
and the location of the center is x equals zero and y is 120
and it's a radius 25, okay?
So it should end up tangent to the R20 below it.
Then we're going to create 2 other smaller circles
in the same locations as the center, one is a radius 12
and the other one is a radius 5, okay?
And then we're going to create 2 vertical lines
for the ... follower up there
so it's going to be vertical line.
To make sure it's vertical I'm going to click on, on,
on ortho so it's vertical.
I'm going to assign a length of 85 to that.
The length is arbitrary so I just type the length.
And then the next thing I'm going to do is I'm going
to offset that and make a copy of that to the right,
which is 24 units, a slight offset on the right side, okay,
and then I'm going to connect the top of this too.
The next thing I'm going to do is I'm going to create a block
for the followers, insert create block,
name of the block is follower, and then select the entities.
It looks like I'm in the lasso so I'm going
to lasso everything, that includes the follower, okay?
Press enter after I selected my objects
and then pick the base point.
It will be the center of the circles and then press okay
and just to verify it is, indeed, now a single block.
Okay, next thing we're going to do is we're going
to create the 2 rectangles that are hatched that serve
as the guide, the guide for the followers.
So create a line.
We're going to make sure that they are horizontal
and vertical by doing ortho.
So I'm going to create a line of arbitrary length here
and then I'm going to create another line vertical
arbitrarily, let's say the length is 16 units.
I'm going to type 16 on here.
And then for the third closing site I'm just going to offset
by 16 because that vertical line is 16, this upper part here
on this side here, and then I'm going to mirror those 3 lines
to the other side so press enter
and then my mirror line will be a vertical line passing
through the center of the follower.
Okay. And then no, I do not want to erase
and then I'm going to hatch.
Okay, it's ANSI13 okay
so select hatch the areas inside and then I'm done.