Compound, complex curves

Ken Close

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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
 

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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.
 
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 :wave:,
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.:D
Shaz
 
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
 
Oops, my mistake. I thought you were interested in doing curves in SketchUp. :eek:
Hi Dave:wave: ,
I thought so too:D ! 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! :thumb: :rofl::rofl:
As always,
Stan :)
alias
Shaz
 
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
 
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!
 
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;)
 
Dave: I am getting confused by the replies.
Hi Ken :wave:, It is not your fault, ( it is dave's :rofl:) I just find Dave a real pleasure to interact with. Sorry..:(..Shaz :)

Ken

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! Hi Ed :wave:, Thank you for the clarity. It is just a fun thing that "Ollie does" every so often! :rolleyes: He means no harm, Do ya Ollie? :D:rofl::rofl:

You are good for other people's mental health Ollie! Now, Where did you say that piano was? ( looking around :huh:)..:rofl:
Stanley :D
 
You are good for other people's mental health Ollie! Now, Where did you say that piano was? ( looking around :huh:)..:rofl:
Stanley :D

L%20&%20H%20Music%20Box.jpg
 
Say Dave/Ollie:

You said:

» I don't find any limitations in doing this sort of thing in SketchUp.

I wonder if you could look at the attached picture of a baby crib. The front edge of each side/leg is a multi-curved piece that is the one giving me the fits and which led to this entire thread. Even with the Bezier tool (which I found in the Draw menu not the plugin menu:doh:) I find that creating the curves, knowing where the centers are (to facilitate machining the part) and making sure of tangencies, says to me that this kind of curved piece is just not suited for SU. However, that is my inexperience talking and I am sure that an experienced SU user like you can bat something out in no more than two minutes. Care to try and comment along the way? No problem if you do not have time or inclination, just thought I would toss it up there.

Ken

PS: I am designing and want to make a companion baby changing dresser and have it match somewhat in style to this crib design.
 

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Ken, you found the Bezier tool in the Draw menu as I said although the Bezier.rb file is in the Plugins folder. Good.

I'll give your crib profile a go but right now I'm trying to reassemble a transport ventilator. Life support equipment needs to come first right now. I'm sure you'll understand.

Dave/Ollie
 
Dave: the crib is listed at 48Hx39Wx55L. For the design I am working on a stile would just be 36in high. Whatever you can do and whenever you can do it would be a great learning experience for me.....thanks.

Ken
 
Alright, the vent is reassembled and the bonus is that it works! :thumb::D

Here was a quickie. I found a different picture of the crib showing more of the end and used that picture for PhotoMatch.
crib.jpg


I placed a bunch of intersecting guides to mark out straight edges and important landmarks on the leg including the center of the circular detail at the top of the leg. I used the center of that circular detail to create the profile at the top of the leg--another circle. Then I added straight lines down the back and across the bottom, an arc from the bottom of the leg to the back with a very shallow bulge, another one at the top and the back edge was completed.

A 4th degree Bezier curve was used for the bulge on the front and a couple more arcs to connect the bulge to the bottom line and top circle. A little clean up, Push/Pull and scaling to size and done.

Is this close enough to give you some ideas?

criblegs.jpg
 
Very nice....it certainly gives me some more specific ideas to try my own. Guide lines are certainly important. I still am not very comfortable with drawing the Bezier curves (still have not figured out how to change the default 3 points---is that what you meant by a 4th degree Bezier curve?). Ah, now I have it--have to hit enter after changing the number of points) Still, this gets me going in the right direction.

I sincerely thank you for taking to the time to work it out and share it.

Ken
 
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Glad it helped Ken.

BTW, when you are working with the Bezier curves, you might find it easier to start with a large face. Think of it as a sheet of paper to draw on. Then add your guides, draw the curve, manipulate it as needed (select the curve and right click. Choose Edit Bezier curve.) and once you're happy with it, delete the face. Or draw the rest of the profile on there as well, delete the waste and Push/Pull as desired.

The Bezier tool will draw 3D curves so starting out with a face is useful.
 
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