1. Member
Join Date
Sep 2007
Posts
69

## Compound, complex curves

I am looking for help in drawing/constructing complex curves (in a single plane). An example could be the starting profile for a cabriole leg. I have seen and understand several videos (one from the Tauton site) on making the leg after having or drawing the complex shape in a single plane. How to draw the shape is what I need to know how to do.

There are other various smooth, gentle undulating surfaces one could make that have large radii, radii which are different in dimension and which are tangent, and radii which are drawn from opposite points. As this is somewhat a confusing word description, below is a hand-drawn example of what I am talking about. How do you draw this using the drawing tools?

Thanks for any pointers.
Ken

2. Ken, there are a several ways to do complex curves in SketchUp. One would be to simply combine circular arcs and line segments to create the shape. Another would be to use the Bezier plugin. A third would be a combination of the two.

Keep in mind that you can scale individual elements--arcs, Bezier curves--if needed.

After creating the complex curve but prior to running Follow Me or Push/Pull, use the Weld plugin to weld the segments together and save yourself a bunch of softening work after the extrusion.

3. Originally Posted by Ken Close
I am looking for help in drawing/constructing complex curves (in a single plane). An example could be the starting profile for a cabriole leg. I have seen and understand several videos (one from the Tauton site) on making the leg after having or drawing the complex shape in a single plane. How to draw the shape is what I need to know how to do.

There are other various smooth, gentle undulating surfaces one could make that have large radii, radii which are different in dimension and which are tangent, and radii which are drawn from opposite points. As this is somewhat a confusing word description, below is a hand-drawn example of what I am talking about. How do you draw this using the drawing tools?

Thanks for any pointers.
Ken
Hi Ken ,
I am thinking you are asking for input that Dave Richards can help with on the computer.
If you are drawing on paper, I would scale 1" to 1" on paper the height. Mark off a straight vertical line to full height.
Determine the narrowest distance to be had in your shape (laterally) from that line.
Draw a parallel vertical line.
Next determine the widest dimension of your design from that first vertical line.
Draw a parallel line at that width vertically.
(you now should have 3 vertical lines, the first denotes the back of your design the next is the narrowest dimension of your design, and the 3rd line is the widest or outtermost dimension of your design at the widest point.
Have I been clear so far?
At some point down the road I am going to use a large french curve.
Once you have the lines done, decide on the vertical line where you want to put the narrowest dimension, and the also decide on that vertical line where you think the widest point of the design should be. The lines merely serve as limits to the size and points of reference for your design.
Then get your self a large french curve and have fun. Make your transitions graceful.
I hope this is understandable, if not, highlight all, PRESS Backspace.
Shaz

4. Member
Join Date
Sep 2007
Posts
69
Shaz: Gulp. I indeed was thinking of SU on the computer, but your description got me thinking.....somehow it came to mind that I would find a large compass and strike some arcs. It also reminded me of creating the parts for a 10 foot bridge I built out of 2x12s across a small swale in the backyard. The radius on the arcs I needed was around 21 feet, but I anchored a string and measured out 21feet, attached a pen and struck the arc....but this digresses.

I went to a tool demonstration yesterday at ClermontWoodWorking (http://www.clermontwoodworking.com/ ) in Clermont County Ohio (you can look it up on google). The owner is a member of the Cincinnati Woodworking Club and held a meeting there. In talking with the owner, who is a Master of Woodworking and has studied under a bunch of world class woodworking experts, I asked him about how he designs his projects and which CAD package he uses. He laughed and said that after experimenting with several including AutoCAD, he junked them all in favor of hand drawings full scale. He said it was the only way he could get a "feel for" the joinery.

Not my cup of tea but you can see some of the most beautiful custom furniture on his site.

Thanks for the description.

Ken

5. Oops, my mistake. I thought you were interested in doing curves in SketchUp.

6. Originally Posted by Dave Richards
Oops, my mistake. I thought you were interested in doing curves in SketchUp.
Hi Dave ,
I thought so too ! I was bored and felt like sharing the old french curve deal anyway. Surprising, sometimes things are okay..I knew you would know how to do it the Sketch up way. You're brilliant Ollie!
As always,
Stan
alias
Shaz

7. Originally Posted by Robert Schaubhut
You're brilliant Ollie!
As always,
Stan
alias
Shaz
Thanks Stan. We should go move that piano now.

8. Member
Join Date
Sep 2007
Posts
69
Dave: I am getting confused by the replies.

I AM interested in making these compound curves in SU.

I am using SU6 and the bezier.rb does not work because it needed a sketchup.rb which will not work with ver6. I have ver5 so I will try it there.

I just made an approximate compound curve in two drawing programs and imported DXF files into SU and pushed the shape, so that looks like the easiest way to get the profile on the part I want.

Overall, it seems there are some limitations to doing this in SU, or at least it is more difficult, but the import option makes it easier.

Ken

9. Hey Ken. Don't let Laurel and Hardy confuse you.

Dave, aka Ollie, is the one to ask SU questions to and is extremely helpful. Shaz, aka Stan, is also very helpful in the traditional methods!

10. Originally Posted by Ken Close
Dave: I am getting confused by the replies. Sorry.

I AM interested in making these compound curves in SU. Oh, good. That's what I know how to do.
I am using SU6 and the bezier.rb does not work because it needed a sketchup.rb which will not work with ver6. That's not correct! Bezier.rb works just fine with SU6. I use it all the time. In V6, sketchup.rb lives in the Tools folder under Google SketchUp 6. If you put a copy of sketchup.rb in the Plugins file you will have problems. sketchup.rb should already be in the Tools folder. If you haven't already done so, go to Window>Preferences>Extensions and click all the boxes. Delete sketchup.rb from the Plugins folder if it is there. Close and reopen SketchUp and Bezier Curves should be available in the Draw menu. I have ver5 so I will try it there. Or you can just do that if you prefer not to have it working in SU6.

I just made an approximate compound curve in two drawing programs and imported DXF files into SU and pushed the shape, so that looks like the easiest way to get the profile on the part I want. Or, since you have other applications to do it you can do it that way.

Overall, it seems there are some limitations to doing this in SU, or at least it is more difficult, but the import option makes it easier. I don't find any limitations in doing this sort of thing in SketchUp.
Ollie

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