Curviloft surface of 2 arcs in 2 different planes

I want to create this surface using Curviloft as shown in the image attached


Do you mean the cheek of the block? Curviloft would be a good choice. I would draw a quarter of it and get the surface. Then copy and flip to make the rest of it.

This is just a quickie from eye balling the photo. It could use some refinement and it would be nice to know what the real dimensions are.

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I have drawn 2 arcs. One is in the xy plane and the other is in the xz as shown in the attached image using the loft by spline tool and the result is incorrect. Not sure what you mean by drawing a quarter of it. Are you drawing 2 arcs?

The real dimensions are 4" by 2 1/2’ by 1 1/4" thick

I used 4 curves, actually. Three are Bezier curves and an arc at the bottom since the cheek doesn’t come to a sharp point. Then I used Skin Contours to create the surface.

!-1/4 in. thick for the entire block? How wide is the sheave?

The sheave is 1/2" wide and the block is 1 1/4’ thick at its thickest point in the center just as you’ve modeled it. I am looking to 3d print this and sand cast the part in bronze. There will be a 1/2" cylinder at each end of the block slightly inboard of the end.

You can draw it as a single piece rather than drawing just a quarter of it. You’ll likely run into the small faces issue so plan on using The Dave Method to get around that.

Well, that was a fun diversion that kept me from working on what I should have been doing. :smiley:

Too lazy to draw the shackle.


Hi @DaveR

Liking this a lot.

A full understand the process but one thing I’m trying to get to grips with, (and I more often than not confuse myself in my own head), is the bezier curves, and making them meet so there is not a point. Tangential I believe is the correct term.

Kind regards


Thank you, Mike. I used odd numbers of segments so there’s a flat where the curves meet.

Something I’m going to have to play with. I’ve been using the Bezier Curve extension, by Fredo. Very good, but I need to experiment with the control points to make sure the ends are tangential to the next component.


That block looks fantastic! Would you be able to post the sketchUp file so I can try to figure out what you did?



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