Unfolding a 3-d model into 2-d sections


#1

I’m very new to Sketchup. My apologies if this is an elementary question.

Suppose I model a simple dinghy: 2 sides, bottom and stern, along with all the resultant compound curves. I now want to unzip the intersections and unfold the model in order to cut the 2-d shapes out of plywood.

Or in reverse. Suppose I model all the 2-d plywood shapes needed to make my dinghy and then wish to join the edges together to model the resulting 3-d shape. How would I go about doing this?

All advice gratefully received. :slight_smile:


#2

There are some extensions such as Flattery which is in the Extension Warehouse could be useful. Keep in mind that the faces in SketchUp can’t be bent like a piece of plywood. You may find that you have to have gaps in the panel when you unfold it in SketchUp that wouldn’t be there in the plywood.

This would be more involved and would take a great deal of work to get right. You might be able to use something like Shape Bender but even that gets to be challenging with compound curves. I think your time would be better spent drawing the hull in 3D instead of trying to make flat planks and bending them to fit.

For drawing the hull in the first place you can set up frames and molds as you might with a real hull and draw curves to pass through points on each frame. Fredo6’s Bezier Spline would be handy for drawing the curves. Then his Curviloft or TIG’s Extrusion Tools would be good for creating the skins. Of course none of the extensions I referred to will work with the web-based versions of SketchUp so you’d either be doing it all manually or you’ll need to use the desktop client version.


#3

Thanks for that, DaveR. I’ll have a look at those extensions.

One more question. Does Sketchup allow you to measure the actual length of a curved edge, not just its projected length? If I make a model dinghy, then these actual lengths could be transferred on plywood.


#4

Yes. To a point. It depends upon the type of curve. There are some potential places for errors such as if a curve has been exploded. Since SketchUp represents curves with series of short line segments, the precision of curves may not be as high as you want. The more segments you use for the curve, the more precise the length measurement would be. When you select a curve, Entity Info will display its length.

Example:

I drew an arc, copied it and change the number of sides. the far one obviously has 3 sides, the center one has the default 12 and the near one, 96. Since by SketchUp’s reckoning they are arcs, the length is shown correctly as if they were real arcs and not a bunch of straight segments.

I exploded the arcs and then welded the segments. SketchUp now calls these curves, not arcs.


#5

I can see why you’re called Sketchup Sage… :sunglasses:

Thanks again.


#6

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