Limiting Joint Movement

advertisement
TECHNICAL WHITEPAPER
Limiting Joint Movement
In my last white paper Assembling with Joint we went over the basics of how the Joint tool
works. In this paper we will take a look at the second tab in the Joint command, the Limits
tab. We will learn how to control the movement of rotational, slider and cylindrical joints to
make them move the way we want them to. We will demonstrate how limits can provide us
with a very robust model that moves how we would like.
Rotational
As discussed in my previous paper a rotational joint allows a part to rotate around an
axis. We will now learn how to control to control this rotational DOF. For instance if you
want to limit part rotation to an angle range Start by creating the rotational Joint. Select
the Rotational option type and adjust the gap or offset to suit your needs.
In This Paper
Rotational
Slider
Cylindrical
About the Author:
Chris Griffith
Once the Joint is placed you will see that the constrained component turns freely
about the axis. In this situation, this particular part should not rotate freely and
should have limited rotation to a set amount of degrees. Click on the limits tab and
assign these parameters to allow only limited movement.
February 2014
Once on the Limits tab you will notice that there are two
options, Angular and Linear. For the rotational limits we
will focus on the angular limits (note: the linear is not an
option in rotational limits). Under these two types are the
Start, Current, and End options.
We will start in the middle with the Current option. This
displays the current angle of the component as compared
to the alignment arrow. From here we will select the start
box as we enter in angles we will see a blue line showing a
preview of the Start angle we have entered. We will then
enter the End Angle and also have a preview. Adjust the
angles as needed until you reach the desired results.
Note: The flyout on both the Start and End boxes allow you
to use the measure command or previously entered angles
to reach your solutions also
Page 2 • Limiting Joint Movement
imaginit.com
February 2014
Slider
As discussed in my previous paper Slider allows a part to slide along an axis/plane. Here we will now learn how to add control
to this joint type. For instance if you have a part that needs to slide in a slot, you can add limits to control the length it will slide
on in the second component. Start by creating the Slider Joint. Pay special attention to your alignment in this step, it will
determine what axis/plane the component slides along. If you select the incorrect alignment have no worries it can be edited.
In the images below you will see that without limits we are able to move it past the stopping point of our slot. To remedy this we
will add a limit that only alows it to move as we wish. In this example the Angular limit option is not selectable, we will be
working with the linear limits only. You will see a blue line as a preview of our Start and End limits.
Note: The bolt’s visibility is turned off for ease of viewing.
Notice how when combined with other components that have Joints or constraints this assembly becomes a very robust model
with complex moving parts. In this example it allowed us to test a number of suspension positions. We will now continue adding
other joints to provide real world actions and limits to end with an assembly with very realistic movement.
Page 3 • Limiting Joint Movement
imaginit.com
February 2014
Cylindrical
With Cylindrical joints, as shown in my previous paper, you can apply both a rotational and planer type constraint used in
hydraulics or shocks for example. After the joint is placed notice how the rod slides in and out of the shock body and without
limits it has no beginning and end stopping point.
In the following two images you will see how limits are being assigned to allow movement in a linear fashion but only to a
certain extent. Also note the linear dimension previews associated with the limits assigned.
So that is an overview of the Limits option in the Joint command, and though you can see it is a very powerful tool and even
more so when combined with other joints, it is not the answer in every situation. So get started and explore the wonderful world
of joints and joints with limits.
Page 4 • Limiting Joint Movement
imaginit.com
February 2014
About the Author: Chris Griffith
Chris provides standard, custom, and advanced AutoCAD and Inventor training. He treats every class as a
learning experience for himself and the student, which allows him to focus on customer needs and what may
help them become a better draftsperson or designer.
About IMAGINiT Technologies
IMAGINiT Technologies, a Rand Worldwide Company,is the
world’s largest provider of enterprise solutions to the engineering
community, including the building, manufacturing,civil and
mapping industries. With 20+ years’ experience, and more than
45 offices throughout North America, we provide the expertise,
training and support to help companies realize the full power of
design technology, maximize ROI and gain competitive
advantage.
IMAGINiT is a leading provider of Autodesk software
solutions and the largest North American Autodesk
Authorized Training Center (ATC) partner. All of our locations
are supported by a vast pool of engineering resources
focused on developing real-life business solutions for their
local clients.
US/CANADA
800-356-9050
Page 5
5 •• Limiting
Performance
for Civil 3D 2012 (Part 1)
Page
JointTips
Movement
imaginit.com
February 2014
Download