Better, But Sheesh


I’ll have to check my shop notes, but I think this trestle took as long to draw as it did to build in wood. The precision of CAD does not lend itself easily to curved, compound shapes. My head hurts so much that I want to build a birdhouse in CAD to decompress. That’s sick.

— Christopher Schwarz

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13 Responses to Better, But Sheesh

  1. Kinderhook88 says:

    How did you solve this problem? Did you cut length off the top, or remake them?


  2. davidcockey says:

    ” The precision of CAD does not lend itself easily to curved, compound shapes.”
    Depends on the particular CAD software. Some CAD such as Rhino excels at shapes with multiple curvatures.


  3. jbgcr says:

    Perhaps raise the decorative piece above boot height so the round parts with holes don’t get kicked off. Maybe mortise this part into the legs.


  4. Max Eskin says:

    Do you use SketchUp? There are better programs out there.


    • I use SketchUp because it is the common tongue of the industry I work in. I’ve used many, many drafting programs in my career – some better and some worse.


  5. calebjamesplanemaker says:

    I felt a bit like that after drawing the bent arm bow of the continuous arm chair for Curtis. Mind melt.



  6. davidcockey says:

    With SketchUp as the software of choice for the enthusiasts and at least some of the professionals, will the capabilities and limitations of SketchUp influence furniture design and what is published? Will designs be modified to conform to SketchUp?


    • Probably no more than the table saw or any other tool that favors 90°….

      As mentioned earlier, I don’t use SketchUp to design. I like designing with a pencil. I use SketchUp to communicate the design after the project is complete. I think there’s a big difference in that approach.


      • dpthew says:

        And that is how draughtsmen originally worked. My first mentor used to have to create drawings from what the “mechanic” built. Now the world is back to front, I draft and then it is built.


  7. jenohdit says:

    davidcockey has it right, it isn’t the precision of SketchUp that is its problem, rather its lack of precision compared to programs like Rhino.

    There are no curves in SketchUp, only straight line segments.

    A “circle” in SketchUp typically is made up of 20 or so (variable by choice, but still limited in number) short straight parts. It’s really a 20-gon. That’s fine until you need to do something simple like find where 2 circles intersect, draw a tangent to a circle, etc.

    Mathematically speaking if a circle of radius A and a circle of a radius B are at a distance A+B apart they meet in a single point. In SketchUp they might not meet at all. Only the endpoints of the line segments in the simulated circle are at the specified distance from the center. The 20-gons can be rotated so their vertices meet, so a simple cyma can be drawn as a continuous curve relatively easily. Adding an 3rd circle of a specified radius and location might not allow continuity.

    I’m rusty on SketchUp but I’d spend less than 30 minutes to draw that in Rhino which I’m also a bit rusty on. I don’t say that to brag, someone good would do it in less than half my time in either application. Just like cutting dovetails, it’s a matter of practice, technical know-how, and the right tools. Given SketchUp as a chosen medium, the BezierSpline plugin is a must have if you don’t. That will save tons of time over connecting arcs.

    The quickest way to draw something like those stretchers is to scan or photograph it straight on and draw directly over that imported image. Trace and scan if it’s too big for the scanner. Draw half and then mirror if it’s symmetrical. Draw using principle views and then move to position and tilt as necessary.

    It’s tempting to draw from the detail to the whole in any medium, but it’s always best to draw general overall layout lines (or planes or points) first. That can help avoid problems like legs crashing together late in the game. In SketchUp you can do that quickly on a layer that you turn off. Make them components since they will stick even when not visible.

    Also, those reversed faces like the tapers at the tops of the legs can cause all kinds of confusing problems. It’s always good to fix that as soon as you notice it.


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