Friday, November 4, 2011

Engine: 7 - conrod, part 1

In recent versions of FreeCAD you can find graphical tool called Loft. It helps to make an extrude based on two or more sketches.
Create a sketch with H-like shape, it will be our conrod cross-section.

Next create two copies by selecting the sketch and using menu Edit-Duplicate Selection. You should have 3 sketches: Sketch, Sketch001 and Sketch002.

Translate the Sketch001 (~80 mm) and he Sketch002 (~100 mm) along Z-axis. You have to change Placement-Position in Property view tree (the sketch should be selected during operation).

The sketches should be different, so change some dimensions.

Now you can open the Part workbench, and select menu Part-Loft... Then move all sketches in the Task view to the Loft field. Check also Create solid option.

If effect isn't good, you can re-edit sketches.

Download file.

Download RAW Video.

FreeCAD 0.12 5088 SVN


  1. For those working with french laguage menus, "menu Part-Loft" translation is "Lissage". Took me time to find out, so I share, just in case.

  2. I switched from French to English about 5 minutes after beginning to follow this tutorial - my recommendation to all French speakers!

  3. I wonder if the result I get in the attached screenshot is the result of a bug or of my own mistakes. Anyone has a clue to sort it out?

  4. Better late than never I guess.

    The loft utility has a "Create solid" option that you can check. Once a Loft object is created, you can also set this parameter under the Data tab, change the "solid" option to true.

    But I'm pretty sure it's not the problem here, because then you would have gotten a complete set of surfaces with open ends. This makes me think the problem lies with your sketches. Edit them and make sure the line endpoints are connected with a coincident constraint. To know if a point is connected or not, pick it while keeping the mouse button pressed, and drag away.

    Where the surfaces start is I believe where the profiles are open.

  5. I'm the one who translated Loft to Lissage. This is how it's called in commercial software such as SolidWorks and Solid Edge.

  6. Why? Just look at the icons! :P

  7. Thank you for the answer.
    My sketch is indeed under-constrained, yet I have tried to move every single point and none of them moved. Is there any way to display where a sketch lacks a constraint?

  8. Not at this point. It may be possible in a future release of FreeCAD.

    If you want you upload it somewhere and paste the link here or join the FreeCAD forum where you can attach FCStd files, and I'll have a look at it.