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Sometimes it's the last simple thing
Hi Folks, don't expect anyone to be up at this hour.
Earlier I finished an assembly I needed to finish a small machine, This was a centering device on a processing machine. it's supposed to adjust automatically when the substrate enters the machine and pull it to the middle of the entryway. My first assembly which I could swear I've made before didn't work and I can't think of why it fails to do what I want.
In the end I added a vertical element with a linear bearing and 2 links connected above the pivots to that to make the arms work evenly, That works fine but I originally wanted to have it simplified and not use that linear bearing in the middle.
so now I'm back wondering why this won't work like the mock up in the attached picture. Thee green elements are bearings for the pivots. the arms are mostly vertical with round elements on the top and there is a link connecting the arms together. The attaching points are the same distance from the pivots. one above and one below. These only have to be opened about 40° and not quite touch in the middle when in the closed position. My thinking was that as long as those distances between the pivot and where the cross link attached were the same on both sides then the arms would travel out and back at the same rate, but in this case one arm travels faster and further than the other... so it can be correct only in the closed or only in the open but not both? I thought I gave up on it too quick.
Hope this makes sense? [IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1175&stc=1[/IMG]