Solidworks Layout Sketch in Assy question

[MattBD]

I made a simple layout sketch and blocks to show the motion of a piston. In the layout sketch, all the members move as they should. The horizontal member remains fixed, the angled bar pivots, and the piston moves vertically.

I made parts from each block. At first, when I went to move the parts, they behaved much like the layout sketch. However, I don't know what happened, but now the parts move independently of the layout sketch. If I drag them, their motion is not constrained. Yet, a rebuild snaps them back to the layout sketch. Likewise, if I move the layout sketch and rebuild, the parts will snap accordingly. It's just the actual part motion that no longer works and I have no idea why.

Can anyone help? SW 2008 assembly model linked below.
-Matt

http://d.cl1p.net/engtipsswmodel/

OR

http://download.cl1p.net/engtipsswmodel/?t=470711719&FILE=26284

 

[SincoTC]

When you made the parts from the blocks, did you select "Project" or "On Block" in the Block to Part Constraint options? The latter Constrains the part to be co-planar with the plane of the block in the layout sketch. Also the parts need to be constrained to the layout sketch.

The (virtual) parts in your assembly don't appear to be so constrained, I added a few coincident mates and slaved them to the sketches so they can't be dragged out.

I have used blocks and layout sketches quite a lot when designing complex mechanisms, but once I've finished the iterations and feel that it's going to work OK, then I open and save all the virtual parts as the basis for real parts and create a conventional mated assembly, then you can dynamically drag the actual parts around in real time and not have to drag the layout sketch and wait for the update.

I only really use layout sketches (in the manner that you are trying) for non dynamic situations, for example, when I have a lot of components to "lay out" on a tray or PCB. I can block and create all the virtual components then locate them with the sketch so that I can see how they might fit without messing with loads of distance mates.

Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

SW2007x64 SP3.0 Pentium P4 3.6Ghz, 4Gb Ram ATI FireGL V7100 Driver: 8.323.0.0
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