CV Joint Mechanism

I have very little experience with Mechanism, and yet I am trying to assemble a custom designed CV joint, which is a very complex joint. Can someone lay down some ground rules for mechanism for me, since I am running into what seem like assembly problems. I keep getting the error "The mechanism constraints can not be satisfied. The Mechanism can not be assembled." when I try to run a mechanism analysis. It seems like mechanism doesnt like more than one constraint on these joints, and I cant capture the motion I need with one constraint.

OK, so maybe my first question was too general, here is a specific problem I am having; I'm using a pin constraint, but I need additional contraints to reference an assembly axis to hold the part in its correct position while in motion, but each time I try to add a constraint in addition to the PINto any assembly features using ball, cylinder etc,I get the dreaded warning"The mechanism constraints can not be satisfied. The Mechanism can not be assembled." Any suggestions on how to make reference to assembly fetures like axis or datums that wont lock the motion? There must be a trick to this? In wildfire 3 there is a General constraint, can these be used and still maintain motion?

Q. There must be a trick to this? In wildfire 3 there is a General constraint, can these be used and still maintain motion?


Ans. yes


just attach your parts/assembly and I will fix it for you.


Israr

I ran across a similar problem. The CV Joint that I was utilizing had one side that could rotate and the other side could rotate and slide in and out. My solution was to take the cage for the slipjoint and constrain it into the bell with a sylinder connection, allowing it to slide back and forth. Then I createe two Datum Points on the center shaft and two Datum Point, one within the cage and the other within the other bell. Then a ball conncetion between the two allows the required motion.
Good luck, hope that helps,
Jim Giacchi

Unfortunatley the design is a proprietary one, so I can;t let it out of the office. But, why am I getting those annoying warnings, "The mechanism constraints can not be satisfied. The Mechanism can not be assembled."


It seems like the only time I can get movement is when the parts only have 1 constraint on them, when I fully constrain the part, I get the warning, and I've tried every combination of different constraints I possibly can. General and cylinder, pin and general, cylinder and ball, ball and general etc. Nothing works. What am I doing wrong?

You may need to delete some constraints to get the mechanism to solve. Then you can add more constraints while verifying that the mechanism can still be solved. You should add any gear pairs and slot or cam followers at the end.

What i've found that worked for me was leaving components partially constrained, then using additional component that were added later in the assembly processto finalize the constraints. For example I used a pin joint in a few places, but that didnt fully describe the motion I needed, so I later added a slider and a general alignment that constrained it for proper motion. With ahuge amount of trial and error I got it working.


It seems to be a bit of a blackart to get complex assemblies like CV joints to work, I suppose thereare some logical rules to it, I don't fully understand them, perhaps with more practice.

start with Kutzbach Criterion. work on redundancies. things start falling in order