- [Instructor] So now I need to make the modifications
to the rib.
That rib is basically an extrusion
that was drafted and removed from the core block.
So I want to go back to the original feature
to make those modifications.
I don't want to add features if I don't have to.
But in case I do have to add a feature,
I want to make sure I follow along
with the methods that I used to initially
put the rib in place.
I would add the feature to the core block
so the core block does the final removal.
Now, when I double click on this Extrude,
you're going to see it's a symmetric 1.25.
It is the thickness divided by two.
What the system is doing is it's taking this line,
offsetting it 1.25, 1.25, so I have a total
rib thickness of two and a half.
It's actually a little thicker down at the bottom
because of the draft that I have put in.
Now, I want to modify this.
So we'll go into the formula,
this is going to be a ratio.
Engineering will probably give you a ratio
or the manufacturer will give you a ratio.
What is your basic minimum or maximum wall thickness
for your ribs?
It's going to be 50% of wall thickness,
60% of wall thickness, 70% of wall thickness,
whatever that's going to be, it's going to assure
that you don't get those little sinks on the A side.
And depending on the material, you could use
a thicker wall or you may need a thinner wall.
If it's a high glass fill, those don't have
a tendency to show or sink as much on the A side
so you could probably use a one to one ratio
wall thickness to rib thickness.
Whereas if it's something like a nylon, a poly pro,
it could potentially sink a lot
so you may need to use 50%, 60% of the wall thickness.
In this case, I'm going to go to divided by four,
which will give me a 50% overall on that rib.
And again, it's going to be a little thinner at the base
where it comes into the part because once again,
it's being drafted.
So down at the very bottom it's going to be slightly thicker
than that 50%.
So I'm going to go check wall thickness,
and I want to rerun this.
Now to make sure I get an accurate display,
I'm going to turn off my draft analysis.
We'll go to Rolling Ball, and this time I'm going to
calculate the thickness.
As I calculate that thickness, it's going to go through
and verify, you can see it's calculating down below
that what I have is acceptable.
And you can see here,
there's very, very faint traces, almost nothing
on that A side, so that's a good sign.
This is telling me that I don't really have to worry
too much about sinks.
I may actually have to go a little thinner
depending on, again, the type of material,
but this should be an acceptable condition
to get this molded and make it look nice.
Because there's really, it's almost imperceptible.
You'll notice here in those corners that
I have potential for issues, again,
that's because it's a sharp corner.
You may break these or, again, depending on material,
that may not be an issue in the future.
So verify that you have good wall thicknesses
to make sure that whatever it is that you're molding
does not have any issues with sinks,
witness lines, on the A side.