Constraint for came follower
- Thread starter Antonin
- Start date
Ken226
Alibre Super User
No.
It sure would be handy.
Everything else I would need to get the valve train working in this engine is there, except for that one constraint. The cam ring to lifter roller constraint is currently just circle to circle, so the lifters won't respond to the lobe.
Maybe someday!
Last edited:
Old Geeser
Senior Member
That is a cool work around Ken226. Thanks for the lesson.
Karl
Karl
Don't know if the following is of any help. I'm not exactly an advanced user and am normally the one asking for help.
I looked up an old cam follower tutorial I've got, after seeing this thread.
The cam in that tutorial was basically made with an elipse, and the follower can be made tangent to the ellipse.
However, most cams are not an ellipse so I tried making a custom cam shape from circles, ellipses, etc, then clipping to leave the finished cam shape.
Problem with that is I could not make a tangent constraint to the entire periphery of the cam lobe. Only certain "sections" of the periphery would select.
So then I tried to make a cam from a spline, and just like with an elipse, I could constrain a circle (follower) to the full cam periphery.
As per the tutorial, I rotated the cam with "Precise Placement" and the follower moved up and down, maintaining tangency to the cam.
Of course this requires you design the cam from a spline.
Tutorial attached and a screenshot of the "spline cam" and follower I did as a test.
I looked up an old cam follower tutorial I've got, after seeing this thread.
The cam in that tutorial was basically made with an elipse, and the follower can be made tangent to the ellipse.
However, most cams are not an ellipse so I tried making a custom cam shape from circles, ellipses, etc, then clipping to leave the finished cam shape.
Problem with that is I could not make a tangent constraint to the entire periphery of the cam lobe. Only certain "sections" of the periphery would select.
So then I tried to make a cam from a spline, and just like with an elipse, I could constrain a circle (follower) to the full cam periphery.
As per the tutorial, I rotated the cam with "Precise Placement" and the follower moved up and down, maintaining tangency to the cam.
Of course this requires you design the cam from a spline.
Tutorial attached and a screenshot of the "spline cam" and follower I did as a test.
Well done beefy! Works beautifully! If you set the rotation increment to 1 degree, you get a nice smooth animation. I'd completely forgotten that tutorial. There's so much that can be done using Precise Placement. I've never understood why it doesn't get more attention. See also: https://www.alibre.com/forum/index.php?threads/coil-spring.24881/page-3#post-169039
In case anyone wants to try this. You can drag the cam but it only works correctly with Precise Placement. Click the Apply button to gain focus on it and then hold down your Enter key to drive the animation. You can change the speed and also the rotational direction of the cam, whilst it's moving, by changing the Angle Degrees entry increments of Rotation Entry (using the up-down buttons or your mouse-wheel) Obviously, a 0 degree angle pauses the animation but it starts again once you have a negative or positive entry. Checking Reverse also changes the direction of the cam, even when it's going at full speed : )
I think it needs the implementation of an additional constraint from the D-Cubed 3D DCM
plm.sw.siemens.com
D-Cubed 3D DCM | Siemens Software
D-Cubed 3D Dimensional Constraint Manager (3D DCM) is a geometric constraint solver that increases design productivity in modeling, sketching and simulation.