Creating a CAM Joint For Model Engine Design

[Claudio_Eff]

I have been transitioning from SolidWorks and I have been having  difficulty with mates and joints, as compared with SolidWorks. I am having difficulty creating the Cam Joint in a digital model of a Fire Eater Engine. 

In SolidWorks I would use either a Cam Mate or a Tangent Mate with no issues. here I am having difficulty with contact sets, and joints seem to flip.

I have attached a file of for editing.

Thanks

[davebYYPCU]

Haven't studied the whole file, quick answer is to make Slider 8 Rest position - to be left of the position in the pic, 

As the Cam rotates it will push the Roller Assembly, away from the rest position, and the slider will follow back to the left again as it can.

Limit Contact sets to just the components you need them for.  

Might help....

[jhackney1972]

Contact Sets in Fusion 360 are very weak as you have discovered.  You will have to resort to a Motion Study since the movement of the slider joint is not a constant motion.  If it were you could use a Motion Link which are a lot easier to set up.  I have created a quick Motion Study to show you but if you take your time, I am sure you could get it a lot better.  The Motion Study is of course between the Rev 20 rotary joint (with I renamed Drive Me) and the slider joint 8.  To get the values to plug into the Motion Study you position the wheel at key points and then hover over the slider joint to get the positional value, then add it to the table.  Edit the Motion Study, set it to run continuously and see what you think.

Great design and very clean modeling!  I hope this helps a little.  Your modified model is attached under a different name.

[Claudio_Eff]

Thanks for the tip,

I have enabled the contact set for the cam and the roller and set slider 8 joint to the rest position. Immediately after, the piston assembly reversed, and I could still not get the follower to move. it does stop at the cam when it is in the rest and max positions.

sembly reversed, and 

[Claudio_Eff]

Thanks for your help,

Your file works wonderfully. I'm having a bit of a difficulty trying to replicate the motion study. I can't seem the to be able to select the motion curves as in the picture.

Once I get the motion study to work is there a way that I can get the motion to work correctly just by turning the flywheel?

I do like the fact that I can keep all of the parts/components in the same file. One step above SolidWorks.

Comparing both software suites, mating and animation the cam is a much simpler process in SolidWorks

Thanks

[jhackney1972]

The answer to your question first, NO, a Motion Study is restricted to being run from the Motion Study dialog.  It is one of the hardest and least effective methods of driving a model.  A motion link between joints is the best but this only works related two linear motions and the cam is not linear.  Contact Sets would be the answer but they are very weak in Fusion 360.

I agree, the selection of points on the Motion Study curves is difficult but once you do, you can change the location by the step dialog entry.  You first step, as I mentioned before, is to find key values between the revolve joint and the slider joint.  If you set the flywheel to a position, then hover over the slider joint icon, it will read out its position.  Make a table of these tests and put them in the Motion Study dialog.

If you decide to continue using Fusion 360, do not try and compare it to other applications, embrace the application for what it can do and work with it.

Do not forget to mark you forum post as solved when you feel you have your answer. This allows other users to find solutions to similar problems.

[davebYYPCU]

Me neither, I ran out of time, did not want to destroy the joint sets you already had, but figured you (would) know why the file would / does not behave as required.

Has worked as described in other files.

In the reasonable time spent, after my quick answer I was not able to demo my proposal working, but it should.  I came to believe the contact set is in conflict with other parts, but did not find any evidence.

To prevent the flipping you need some reasonable non conflicting travel limits

Might help....

[Claudio_Eff]

Thank You for your support, and the insights you provided. I'll keep working at it and post a final solution when I'm done. 

I'm learning more and more as I practice using the software.

[Claudio_Eff]

Thank you for your insights and support. I agree that the contact set/joint structure may be conflicting some where that I would never think to look. I'll keep at it and post a solution once I get everything to work.