Simple Mini Engine

[Toptracks]

See attached JPEG, this is a simple and interesting engine that works off a bycycle pump. I am struggling to find the correct constraint that will allow the piston to move in the chamber. As you can see a simple align option does not work as the piston not only moves in and out but also rotates. This is made possible as the piston face is only 0.5mm thick.

I can get the engine to work with a pump but not in NX6. Any Ideas would be gratfully received.

 

[JohnRBaker]

I think you will find that the 'center' of the front face of your piston actually follows a straight-line that passes thru the axis of the cylinder. Therefore create a line in the Component of the cylinder down the center and add a point to the face of the piston. Now constrain, using align, the point to the line in the Assembly. Once the constraints are created you can hide the point and line and it should still work.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Toptracks]

John,

Thanks for your reply, what you have stated is logical. I have added a point to the piston face, however in the assembly it is not possible to select the point without double clicking the piston, once this is done I can select the point, however I cannot select the cylinder hole or any other part in the assembly.

Is there a way that I can see the point on the piston surface in the assembly? I have tried to ensure that all datums etc. are visable in view, however this does not seem to make any difference.

 

[JohnRBaker]

You will need to either set your Reference Sets for the Piston and Cylinder to 'Entire Part' or edit the 'Model' Reference Sets to include the Point for the Piston and the Line for the Cylinder. If you use the 'Entire Part' Reference Set approach, once the Constraints are created, you can change the Reference Sets back to 'Model' and the extra geometry, the Point and Line, will go away but the Constraints will still work.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.