Barrel Cams need three Planes and three Mechanism-Editors

Image of Barrel Cam after it has been transferrred to SolidWorks.

Image of Barrel Cam after it has been transferrred to SolidWorks.
[The Oscillating Cam-Follower and the 'Frame' are not exported].


With reference to the image to the left:

1s   A Plane for the Cam-Follower and Cam-Follower Roller

2s  A Plane for the rotating Barrel-Cam

3s   A Plane for the Barrel-Blank




This tutorial designs a Barrel Cam with a Cam-Track.

It is also possible to model a Barrel Cam with a Rib - see image to the left - so that the Cam-Followers engage with the two sides of the Rib.

Contact us for help if you need to model the Barrel Rib Cam.

The Five Elements for a 3D-Cam:


There must be five elements in the model before you can use the Add 3D-Cam command. The Command-Manager needs you to select the five elements. You must add the elements to three different Planes. The elements are

1.The Part that is the Cam-Follower 1s
2.The Profile that is the Cam-Follower Roller 2s
3.The Part that is the Barrel Cam 3s [Green, in the active-Mechanism-Editor]
4.The Profile that is the Barrel Blank 4s
5.The Sketch Line that is the Barrel Blank Rotation Axis 5s

The five elements are on different Planes. Thus, to see them, you must use 'Show other Sketch-Elements'.

tog_minus        Plane 1: Add the Barrel Cam as a Rotating Part


In this case, the Barrel Cam rotates with constant angular velocity.

Thus, it is a simple Crank. It is best to put the Pin-Joint at the Origin of the Mechanism-Plane.

STEP 1: Add a Mechanism – use the XY (Front) Plane
STEP 2: Edit the Base-Part to add a Line – make it coincident with X and Y-axes
STEP 3: Exit the Part-Editor
STEP 4: Add a Part and Pin-Joint
STEP 5: Add a Motion-Dimension FB and Linear-Motion FB
STEP 6: Rename the Mechanism to 'BARREL' and the Part to 'BARREL-PART'

tog_minus        Plane 2: Add the Cam-Follower Part and the Cam-Follower Roller


The Cam-Follower Part

Add a Plane for the Cam-Follower Part. It is offset from the Model 'XZ' Plane, or the 'Top' Plane2.

STEP 1.Click the Model tab
STEP 2.Click Add Plane in the Model menu or the Model Local Toolbar
STEP 3.Click the Horizontal Plane in the graphic-area or Plane2 in the Assembly-Tree.
STEP 4.In the Add Plane dialog-box, enter 100mm, click OK.
STEP 5.Click Add a Mechanism in the Model Menu or Model Local Toolbar
STEP 6.Select the new Plane for the Mechanism
STEP 7.Click OK in the Command-Manager

You will jump to the new Mechanism tab.


STEP 8.Rename the New Mechanism to CAM-FOLLOWER

Here, I have changed the 'Background colour' to 'White' with the Application Options dialog-box | Colours tab

STEP 9.Select Show Other Mechanisms in the Tools toolbar or Tools menu

This helps you see the relative location of the two mechanisms.

STEP 10.Use the View Front to view the Mechanism normally.

To the left, we have rotated the view to show the relative positions of the elements on the two planes. It is easier to add sketches in the 'Front View'.


STEP 11.Add a Sketch Line and Dimension it so it starts at (-100,0) in the Mechanism Coordinates1s-red
STEP 12.Add a Part and Pin-Joint. Edit the Length of the Part to be approximately 105mm long.
STEP 13.Rename this Part to CAM-FOLLOWER-PART
STEP 14.Add a Motion-Dimension FB, Motion FB and Linear-Motion FB
STEP 15.Edit the Base-Value of the Motion-Dimension to -30º
STEP 16.Connect the Function-Blocks
STEP 17.Edit the Motion in MotionDesigner to give it a RDRD with a Rise of 60º

I have rotated the view in the image above (use your keyboard arrow keys) so that I can view the Barrel Part and the Cam-Follower Part together.


The Cam-Follower Roller

STEP 1.Edit the Cam-Follower Part
STEP 2.Add a Circle Sketch for the Cam-Follower Roller to the end of the Cam-Follower Part.
STEP 3.Dimension the Circle to be 30mm diameter (15mm Radius)
STEP 4.Close the Part-Editor
STEP 5.Add a Profile. Use the Circle as the Sketch-Loop
STEP 6.Edit the Profile with the Extrusion dialog-box to edit the Extrusion Offset to -15mm and the Extrusion Depth to 16mm

I use 'Show Model in Mechanism' to show the Extrusion of the Cam-Follower Roller.

Note: In 3D-Cams, MechDesigner can model only Cylindrical Cam-Follower Rollers.

tog_minus        Plane 3: Add the Cam-Blank and Rotation Axis


Add the Cam Blank Sketch-Loop and Profile, with Rotation Axis

Think of the Cam-Blank as the material before you start to machine the Cam. You cut the Cam into the 'Cam Blank'.

In CAD, you will find a command you can use called 'Revolve'. For this command, you will usually need a closed sketch-loop and an axis or rotation.

In this step, you specify the Cam-Blank cross-section and the axis-of-rotation.

STEP 1: Add a Mechanism to the ZY Plane - see image to the Left.
STEP 2: Rename the New Mechanism to BARREL BLANK


STEP 3: Edit the Base-Part in the BARREL BLANK.
STEP 4: Add sketch-elements as a Sketch-Loop that will encapsulate the motion extents of the Cam-Follower Roller.

It is important that the Sketch-loop is 'clean'. That is, it does not have 'Branches' or sketch-elements that are not part of the sketch-loop.

It is useful to Cycle the Mechanism so you can see how far the Cam-Follower Part and Roller Moves. The image to the left shows the Cam-Follower Roller at one end of its motion.

STEP 5: Add a Line as the Rotation Axis of the Barrel Blank.

The Line should be horizontal and align with the X-axis. The length of the Line is not important.

Do not join this Line to other sketch-elements.

SOLIDWORKS® will use this Line as a Rotation Axis for the Barrel Blank.

STEP 6: Close the Part-Editor
STEP 7: Add a Profile. Use the new Sketch-Loop

tog_minus        The Model ready for Add 3D-Cam


To the left, you can see all the elements to select when you use Add 3D-Cam.

You might also add a Circle and Extrusion to the Barrel Part to give the general shape of the Cam.

Help Files for MechDesigner and MotionDesigner 11.1 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd