It isn’t.
Same number of segments in each arc, different swept angle.
There’s only one arc result in SketchUp, depending on the number of segments you set the tool to and the angle. These segments are equally divided over the angle you draw your arc.
- decreasing the angle makes the arc smoother
- and/or increasing the number of segments also makes the result smoother.
(nicely demonstrated by @DaveR above)
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I think I’ve made this point earlier, What I am doing is simply a different method of creating an arc, and specifically suited to certain types of modeling.
Hi Jim,
It looks as you are not familiar with the basics of SketchUp.
SketchUp uses lines to create all type of curves.
This method is not used in other CAD software I know. If you want to draft, you may try Layout for SketchUP or use a different software like ArchiCAD or Vectorworks.
Non of these softwares are the same, they have advantages and disadvantages. One size doesn’t fit all. This is why most of us use many softwares on our workflows.
I can not see the point that you are trying to demonstrate with the ARC, but keep experimenting and read the Topics on this site as one of the best thing about SketchUp is its community support.
Good day.
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Back in the 1980s (Holy Moly, that’s forty years ago? Sheesh.) when I first began to transition from pencil/pen on velum/mylar 2D drafting, when I got my first 8088 monochrome computer and a copy of Drafix, the terminology describing the technology was Computer Assisted Design and Drafting, or CADD. Detractors (those who couldn’t manage without a #2 Ticonderoga and a roll of tracing paper) prefered the term “electric pencil.”
I had access to AutoCAD 9.0 and got a more powerful computer (with a color monitor) and bought AutoCAD 10, then 11, then 12, then 13…and finally, I happened on that little baby Gee Whiz upstart called SketchUP. (Seriously? I thought. It couldn’t possibly be as powerful as AutoCAD, I thought. Anyone who agrees with this should have an in-depth conversation with DaveR.)
A year later, I let my license for AutoCAD expire, because I was using SketchUP almost exclusively for both drafting AND design work. I still sketch preliminary ideas on paper, but I develop the design and produce working models on the computer.
Does the lack of mathematically accurate circles and arcs bother me? Yup. Enough to generate complaint to the authors of SketchUP? Nope. Why not? Because most of what I do, from architecture to furniture to 3D printed miniatures, is there anywhere NEAR the necessity for curves that are more precise than SketchUP’s default 24-segment circles. I suppose that in very large scale CNC work, more precision is called for (a 24-segment circle five feet in diameter is pretty crude), but for what most of us do, the model on the computer isn’t the final product. It’s a guide for the crafts person producing the product described in the model. And said crafts person will fair the curves to the necessary smoothness with non-computerized tools . . . such as sandpaper.
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What year(s) was this? (just out of curiosity)
AutoCAD 10 was released in 1988. @Last came out with SketchUp in when? 1999, I believe. Someone gave me a disk with version 1 on it. I played around with it on and off, but the muscle memory for doing things the ACAD way was strong, and it wasn’t until Google bought SketchUP that I found it more convenient than messing around with ACAD’s powerful but difficult to use 3D modeling. I skipped the upgrade to ACAD 14, and when I had to buy a new computer, as I was no longer in a situation where I had free access to even reinstalling ACAD 13 (and because Autodesk stopped selling perpetual licenses), I said to hell with it and have been using SketchUP ever since. (Well, there were a couple of years in there someplace when I was given a copy of FormZ, but it’s expensive and other than lack of a few features such as built-in rendering, SketchUP does just about everything I needed FormZ for.)
AutoCAD features I miss: Native rounding and fillets, true arcs and circles (representing them by straight lines is fine, but getting an accurate tangent in Sketchup is often impossible), and the ability to use multiple keystrokes for shortcuts. [A is fine for arc, but there are three arc types and I’m out of easy-to-remember key combinations using just shift, control and alt modifiers. How about AB (for arc with bulge), AC (for arc with center), A3 (for 3-point arc), for just a few examples.]
Maybe when such conveniences will happen before I drop off the twig. In the meantime, I manage.
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Hi Jim9
Jo Here .
Yes create the circle/ curve. Then goto there top menus, select window from the menu the scroll down to Entity Info . Select the circle or curved line you’ve created then in the Entity Info menu change the amount of segments you have in what ever your drawing. By adding more segments, the more you add the smoother the shape becomes . But. note the more segments you add the bigger the file may be too ?
Hope that helps.
Best
Jo
You know you can simply type the number you want with an s and hit enter after you have created a circle or arc. Or type the number and hit enter after choosing the circle or arc tools before creating the circle or arc. I’m not sure I have ever needed to change the segments in Entity Info.
Example of very efficient sequence of keystrokes
Not exactly the same but true circular guides and true arc guides would help to find accurate tangents and accurate intersections. Something that has been asked for by many of us (@jean_lemire_1 for one). A big plus would be that these types of guides wouldn’t make geometry itself that more complex. It’s the math for these guides that has to be dealt with (by SketchUp itself!) in the same, though “parallel” 3D modeling environment.
“Delete Guides” … removing guides after having been useful.
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Because I’m old enough to remember…CAD means computer aided design.
Of course, SU is a CAD program. I can still sense AutoCad sucking the oxygen out of the room.
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The comments about increasing the number of facets can work, but it can greatly increase the file size when doing it multiple times in complex geometry.
Also after creating the curve you can use the smooth tool for a smoother appearance.
Your question and thousands like it are addressed by https://youtube.com/c/SketchUp
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Oh, it does, it does, always has, and likely always will … But SketchUp is a welcome breath of fresh air. For way more reasons than power.
I would welcome selective guide deletion. For example, I place a guide point (rarely a guide line) at locations in components where I want to join them with other components that may have such complex geometry that other alignment methods are extremely tedious. Fortunately, guide points seem to have as much “magnetism” to the cursor as end points. These guides I want to remain; they never get in the way of rendering, or of transferring models to other formats, but the “Delete Guides” command wipes out ALL guides even those nested in components.
To the moderator: I just realized this post is veering away from the topic posed by the OP. I will not be unhappy if it’s better moved to another location. Thanks.
+1 for keeping guide(point)s that are within a locked environment. A locked group of component container should protect all entities inside. There is an extension FAIK that enables selectively deleting guides.
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tpdes’s comment about SU guiding further work, as opposed to being the end product, is a good one. I’m a woodworker and mostly use it to design and plan furniture and architecture. Sometimes my work is very geometric, and I often need accurate tangents and intersections.
Unlike tpdes though I am often inconvenienced by segmented curves. It’s so much easier and more accurate to plan and measure from the dimensions given by CAD than to construct or draft full size. A couple minutes at the computer can save an hour or more of time. I can’t count the occasions I’ve had to pause in my drafting to compute the optimum number of segments, and the proper orientation, for a particular arc or circle to give me the information I need to set a rip fence or crosscut guide.
I used to do this in Canvas, the late great all purpose drawing/photo/text program, which could also export/import a decent DXF file. Sadly, computers that can even run it are ten years old now.
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Select the guide point and delete or use the eraser.
Because there are limited native tools for drawing curves, I’ve done my best to really understand how the arc tool works. At least in my experience, I’ve found it needs “help” to make curves tangent to lines. By that I mean I need to guide the arc tool along the lines, and in some cases use “helper triangles” to get the tangents I want.
Here’s an example involving the wires found within electrical cables. The end result is like this
And the process to make the twisted wires is like this:
The key in each case is how to make “s-shaped” curves which are tangent to the desired lines. Here is step-by-step explanation of the above screen recording:
To make each of the twisted cylinders, draw…
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a line between each end circle
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a short perpendicular line from each circle
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a line connecting each perpendicular
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remove line (1)
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a helper triangle with sides perpendicular and parallel to the end circles
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an arc from the triangle corner to the middle of line (3)
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an arc from the middle of line (3) to the other triangular corner
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remove unneeded and use follow me tool
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