﻿ Step 7.4: Edit the Dimensions in the Design Set

# Step 7.4: Edit the Dimensions in the Design-Set

### Edit the Design-Set.

The objectives are to edit the Design-Set to:

 • Make the radius-of-curvature of the two cams have a minimum value of 20mm
 • Make the radius-of-curvature of the two cams to have equal maximum values.

Measure the Cam Radii of Curvature

 1 Add two Cam-Data Function-Blocks to the graphic-area.
 3 Link the Cam-Data Function-Blocks to the 2D-Cams with the rollers on the left and the right.
 4 Connect the Cam Radius-of-Curvature output from the two Cam-Data FBs to two different input-connectors of the Graph FB
 5 To indicate to which Cam/Roller the Cam-Data FB is linked, rename the Cam-Data FBs to Left-Roller and Right-Roller.

Note: You can also use a Measurement FB and measure between the centre of the cam and the cam contact-points.

Display the Graph:

 1 Double-click the Graph FB icon in the graphic-area. The Graph-Plot opens.
 2 Select the correct Radius-of-Curvature [1 or2] for the the two cams with the Y-axis data-channel drop-down boxes [to the right of the graph-plot area].

Important Notes:

Each 2D-Cam has two Cams: Cam 1 and Cam 2. Thus, you can plot: Radius-of-Curvature 1 and Radius-of-Curvature 2.

For each Cam, use the Y-axis data-channel drop-down [to the right of the graph-plot area] to select which Radius-of-Curvature you want to plot.

For this model, with two different cams, there is a small '2' next to their contact-points. Thus, we want to plot the Radius-of-Curvature 2 for the two cams.

 3 Move your mouse-pointer to the graph-plot area
 4 Drag your mouse when it is plot area of the graph.

As you drag in the plot area of the graph...

 • the Vertical Bar moves with your mouse-pointer
 • the MMA updates so that it equals the Vertical Bar and the kinematic-chains follow the MMA - of course
 • The DRO shows the exact value[s] of the graphed variable at the red cursor

You can edit the Minimum and Maximum graph-plot values in the Graph Settings dialog-box.

I have changed the maximum and minimum of the two graphs to ±100.

 1 Drag the Vertical Bar to put the kinematic-chain in the Dwell Segment of the motion at the maximum or minimum radius of the cam.

Do Steps 1 and 2 again for the other Dwell Segment

Edit the Design-Set

 1 Double-Click the Design-Set in the Assembly-Tree or graphic-area

Edit the dimensions to make the Radii-of-Curvature equal.

 1 Make sure the Design-Set is LOCKED.
 2 In the Design-Set dialog-box, click the Element-Name with the dimension you want to edit, to make it the active Element-Row.
 3 Edit the Property-Val/Dim-Val with the Spin-Box tool

The model updates as you edit the dimension in the Design-Set.

If it does not, then click the Rebuild icon in the Design-Set.

Experiment. You will find many solutions for the design objectives.

Note: It is best to put the Number-of-Steps parameter in the Machine-Settings dialog-box to ~100.

See Edit menu > Machine Settings > Cycling Parameters > No-of-Steps.

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