4 bar hinge motion with dynamic blocks

[Anonymous]

I would like to attempt to create a block of a four bar hinge and have it move through its motion by linking the various movements. The bars would all be set lengths. There is one pinned point and one that would only slide along the x axis. Before I get to far along I was just checking to see if anyone may have done this type of motion before using dynamic blocks. Is this to advanced for dynamic blocks? I am running AutoCAD 2007 (just installed).

[whdjr]

I am not sure what a four bar hinge is but if you wanted to illustrate the blocka and the motion then I could help better.

Also if you post dwgs post as R2006/2004 so people not 2007 can help as well.

[Anonymous]

I have attached a file representing a four bar hinge. Typically used on awning or casement style windows. The motion is simple when you look at the drawing. All the individual parts are drawn as blocks. The four bars move as the window is opened. The track is stationary on the window frame. Link 4 (as defined as a block) is attached to the sash. The shoe slides in the track as the window is opened. The drawing attached shows the hinge in the opened position. When closed all of the bars are aligned with the track within the track length. I am looking at doing this to speed the process for determining stop bar length to control the open dimension of a window. So far when I link my actions they all rotate about the same point and not individually as I would like. Any help would be appreciated.

[tlindell]

Since you're not showing it with the dynamic stuff, I'm guessing, but you can assign a different rotate action to each component, and then in Properties->Overides->Base Type, you can change it to rotate from an indepent base point, separate from the rotate parameter basepoint.

[Anonymous]

I haven't shown any of the dynamic stuff with this drawing because I havn't been able to get it to work anywhere near the way I would like. I have attached another drawing here with some labels and I will try to explain my thoughts on how it should work. I'm really begining to think that what I am trying to do goes far beyond the dynamic block capabilities. Primary movement would be rotating link 3 about the only fixed point in the system. Dimensions a & b are equal as well as c & d being equal. Link 3 and link 1 are parallel as well as link 2 & link 4 (basically the bars create a parallelagram when link 3 is rotated and the shoe slides in the track). So by rotating Link 3 I would like to chain the movement of the shoe and the movement and rotation of the other links. I'm not sure if the rotations of each individual blocked link should be set at their block level then chained at the completed hinge block level. Also not sure how to set up a polar move based on the rotation of link 3 to get the pivot points of links 2 & 4 where they should be. Link 1 should move with the shoe and rotate to the same angle as link 3. I hope this isn't confusing anyone trying to help. I like to try things like this out but I am not extremely confident in my dynamic block skills yet. If anyone knows where I can go to get more info on chaining parameters I would appreciate it.
Thanks for helping....

[tlindell]

Well, I can make it work to the point of being correct in an open and closed state, but not at the distances in between. The swing of the blue components must have a variable rate of movement, which I can't account for. I think you would need something like constraints to make this ideally.

[Anonymous]

That works well for closed and open positions but as you stated it doesn't work for anything in between. So my guess is that this is a little to advanced for dynamic blocks to do. I have gotten close to making some of it work but always seem to miss something when nesting the parameters and actions for chaining the movement. It has been a frustrating experience. It seem's to me that most everything that dynamic blocks will do well has to do with architectural drawing and not mechanical. That's a shame, simple kinematics like this would be nice to reproduce using dynamic blocks. I know it would make my life simpler. Does anyone know of a software package that could accomplish this task? Someone I know said that Solidworks could do it.

[tlindell]

As far as other software, you should ask in the CAD manager forums if you haven't already. I'm sure some one there would have a few good suggestions.

[Anonymous]

Thanks for your help. I have found a plug-in for AutoCAD called Easy-Kinematics on the Cadopolis.com web site. It looks like it will do what I want. Just have to have it approved. The Cadopolis web site says it is compatible to 2002 I just hope it will work in 2007. If anyone has had any experience with it please post. Thanks again.