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 - offset from the Top Plane*

2s   A Plane for the rotating Barrel-Cam - if possible, make this the Front Plane*

3s   A Plane for the Barrel-Blank - the Right-Plane*

* Use these Planes, if the model is to design a 3D-Cam, and does not need to include other machine elements.


Rib Cams.

This tutorial designs a Barrel Cam with a Cam-Track, a groove, to guide one roller with a cam-flank on each side of the one roller.

It is also possible to model a Barrel Cam with a Cam-Rib - see image to the left. In this case, there are two rollers, with each roller against a different cam-flank.

Contact us, if you need help to model the Barrel Cam with a Cam-Rib.

The Five Elements for a 3D-Cam:


You need five elements in the model before you can do Add 3D-Cam. 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 Rotational Axis 5s

The five elements are on three Planes. Thus, to see them, you must use Visibility toolbar > Show other Sketch-Elements.

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


The Barrel Cam-Shaft

In this case, the shaft for the Barrel-Cam rotates with constant angular velocity. Thus, it is a simple Crank.

Add a Mechanism-Editor to the FRONT Plane for the Cam-Shaft, and put Pin-Joint of the Crank at the Origin of the Mechanism-Plane.

STEP 1: Click Model toolbar > Add Mechanism to the Front-Plane
STEP 2: Edit the Base-Part, add a horizontal Line; make the start-Point at the Origin of the Base-Part X=0; Y=0
STEP 3: Exit the Part-Editor
STEP 4: Add a Part and a Pin-Joint
STEP 5: Add a Motion-Dimension FB and Linear-Motion FB

Rename each Mechanism-Editors, to help you identify each later.

STEP 6: Rename the Mechanism to 'BARREL and the Part to 'BARREL'

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. In this case, the Plane is offset from the Top Plane in the Model-Editor.

STEP 1.Click the Model name-tab at the top and left of the graphic-area
STEP 2.Click Model menu >Add Plane [or Model contextual toolbar> Add Plane, which is to the left of the graphic-area
STEP 3.Click the 'Top' [Horizontal] Plane in the graphic-area or Plane2 in the Assembly-Tree.
STEP 4.In the Add Plane dialog-box, enter 100mm, click OK-tiny-13-17.
STEP 5.Click Model Menu > Add a Mechanism  [or Model contextual toolbar >Add Mechanism to the left of the graphic-area
STEP 6.Select the new Plane for the new Mechanism
STEP 7.Click OK-tiny-13-17 in the Command-Manager

You will jump to the new Mechanism-Editor.


STEP 8.Rename the new Mechanism-Editor to CAM-FOLLOWER

Note: Edit 'Background colour' to 'White' with the Application Options dialog-box | graphics tab : display colours. This helps us see the two mechanisms.

STEP 10: Use the View toolbar > View Front to view the Mechanism along the Z-axis.

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 horizontal Line in the Base-Part. Put its start-Point at X=–100, Y=0 [Mechanism Coordinates1s-red ]. Exit the Part-Editor
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
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 with Wires
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.


The Cam-Follower Roller

STEP 1: Edit the Cam-Follower Part
STEP 2: Add a Circle at 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: Do Solid toolbar > Add Profile. , click the Circle , and OK-tiny-13-17 in the Command-Manager
STEP 6: Edit the Profile/Extrusion with the Extrusion dialog-box : 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 3D-Cams can also model Tapered 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 this step, you specify the cross-section of the Cam-Blank and its axis-of-rotation.

STEP 1: Add a Mechanism to the YZ 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 extend 'wider' that the motion extents of the Cam-Follower Roller.

It is important that the Sketch-loop is 'clean'. That is, it does not have sketch-elements that are not part of the Barrel-Blank's sketch-loop. It is useful to Cycle the Mechanism so you can see how far the Cam-Follower Part and Cam-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 and coincident with the X-axis of this Mechanism-Editor and Base-Part. 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 to the new sketch-loop

I often edit the Extrusion [child of the Profile] to make the Extrusion-Depth = 2mm and the Extrusion-Offset = -1mm.

tog_minus        The Model is ready for Add 3D-Cam


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

You must use these two tools:

Show Model in Mechanism
Show other Part Outlines and sketch-elements.


Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd