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Mates in an Inverted Barrel Cam

Question asked by 1-7RQIVH on Jul 31, 2010
Latest reply on Aug 1, 2010 by Tom Helsley

Hello everyone.

I´m relatively new to Solidworks, and this is my first post on this forum.

I´m designing a mechanism for my thesis, and  at this point I´m very frustrated with Solidworks.

The mechanism consists in what I have named as an inverted barrel cam.

The intention of this mechanism is to convert linear motion into rotational motion, in a very compact way.

It´s similar to a barrel cam, but with two long helicoidal grooves made on opposite sides of the barrel.

This helicoidal grooves made just 3/4 of a turn on a lenght of about 83 centimeters.

Since the barrel is made out of a thick walled tube, the ideia is to have a cilindrical rod passing through the

center of the barrel, perpendicular to its axis, and through both grooves, forming a cross.

Now, the rod will be limited in it´s motion, to just linear motion, parallel to the barrel axis.

It cannot rotate in any way, in relation to himself or to the barrel's axis.

And, by moving that rod in it´s unique degree of freedom, the barrel will rotate proportionally.

I was able to simulate this on Solidworks using Physical Dynamics, but it´s frustrating, because this feature

doesn't seems to be very deterministic.

Some times it works fine, some other times it simply refuses to work, and from time to time, it crashes everything

when I try to use it, even if I simplify the physical dynamics simulation by selecting only the barrel and the rod to

be the only intervenients in the process.

And, the more subassemblies the project has, the worse it becames.

So, my big question for all of you is:

Isn't there a way to achieve the same result using only mates, instead of the buggy physical dynamics feature?

I spent this last week trying to do eaxactly that, but without any success.

I tried the coincident mate, the tangential mate, the path mate, and in every way that I remembered, but

nothing seems to work for me.

If someone has the slightest idea on how to achieve this with mates, please give me a hand, because at this moment

I really dont know what else can I try.

I have attached an .SLDASM file with that part of the project, for those of you interested in taking a look.


Any help will be of huge value for me.


Thanks in advance.


Francisco Simoes