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new user - cable/pulley system

salmon

New member
Hello, I am trying to simulate an excercise machine that incorporates a set of eccentric cams/pulleys. What I want to do with Solidworks is to create this as either a model or sketch and create some relations that define the system. I am looking to create a set of relations in the sketch mode which will allow me totranslate one point and have the remainder of the sketch move accordingly to help me simulate a system (rotation and translation). The problem that I have is that I am trying to define an overall cable length to go over a set of pulleys and I cannot seem to be allowed to enter this value into Solidworks as it only works if I define a driving dimension on the sketch. The problem is that the driving dimension I want is the sum of the arc length on the pulley and the two lengths that come off tangent to the pulley. These threevaluesare always changing but the overall value is to remain the same.Does anyone have any expertise that may help me?


Thanks


Nick
 
Just to make sure I understand:


Driving Dimension = DD, Arc Length = AL, and Length 1 and Length 2= L1 and L2, respectively.


DD = AL + L1 + L2


It's easy to setdriven dimensions for L1 and L2.The problem is getting a driven arc length dimension- AL may need to be calculated and substituted into the equation:


AL =A * (pi/180) * r


Ais the included arc angle in degrees, r is the radius of the arc; both of which can easily be picked off the sketch using driven dimensions.


So the final relationwould be:


DD = A*pi*r/180 + L1 + L2


Is this what you're after?
 
That would work if I didn't have an eccentric elliptical pulley/cam system. The arc length becomes far more comlicated as it is not a constant radius curve. Possibly Solidworks cannot get the job done but I am hopful that it can. Thanks though for the reply.
 
Any other ideas. One I had but it was a mess was to created a bunch of tiny circles in sketch mode that had tangency relations with each other and an elliptical spline. These tiny circles had the same diameter as the cable that is to be used on the system. The problem comes when I have to unmate circles as I gowhen the rotationis occuring. Anyone ever had any success using the built in macros to help define a system? I hope Solidworks can help everyone out and make this task a lot simpler.





Nick
 

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