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intersecting two arcs to find a point (triangulating to find a point)
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* December 22, 2009, 02:55:19 PM
Hello,

I am new to CAD, as you may see with my question.

I have marked a random (non-radius) curved line on the ground that is for a new fence that is to be installed.

I need to now create a scaled drawing of that curved line for the fence contractor, so he knows how to build the fence in his shop.

I marked a series of points on the curve, then took triangulated measurements, so I could re-create in the office.

QUESTION:

Does TurboCad have a feature where I can swing an arc of a certain length from each end of the curve - to see where they intersect - and thus re-establish that point(s) on paper?

Thank you,
Jamie

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* December 22, 2009, 06:52:38 PM
#1
Hello,

I am new to CAD, as you may see with my question.

I have marked a random (non-radius) curved line on the ground that is for a new fence that is to be installed.

I need to now create a scaled drawing of that curved line for the fence contractor, so he knows how to build the fence in his shop.

I marked a series of points on the curve, then took triangulated measurements, so I could re-create in the office.

QUESTION:

Does TurboCad have a feature where I can swing an arc of a certain length from each end of the curve - to see where they intersect - and thus re-establish that point(s) on paper?

Thank you,
Jamie

Not sure I understand the problem, Jamie. TCad can certainly swing an arc of a given radius from a point whose coordinates are known, but is that really what you need to do? Your description of the project leads me to believe that you have a set of data which consists of the coordinates of a collection of points that lie on your random curved line on the ground -- and that you want to re-create that curve to scale in TCad. Please clarify.

Henry H

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* December 23, 2009, 04:52:21 AM
#2
Henry,

Yes, your description is exactly what I want to do.

Jamie

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* December 23, 2009, 09:03:13 AM
#3
Henry,

Yes, your description is exactly what I want to do.

Jamie

How to draw a curve through a set of points whose coordinates are known: Insert a "Point" object anyplace into your drawing (use a Cross, and in its Properties dialog make it large enough to be easily visible); select it; TAB to the Pos X field of the Inspector Bar and type the correct X coordinate; TAB to the Pos Y field and type the correct Y coordinate; press Enter and the point will move to that location. Repeat for each of your known points. Then activate Spline by Fit Points and, using Vertex snap, click on each Point object in turn. Right-click to open the Local Menu after snapping to the last point and, if your fence line is a closed curve, choose "Close"; otherwise choose "Finish."

Henry H

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* December 25, 2009, 10:37:03 AM
#4
Henry,

Thank you - this is working out well. 

I have a couple of follow up issues:

Once I have made the crosses large enough to see, and laid down the curve, the crosses are now a distraction. 

Is there a way to select all the crosses at one time, so I can make them small enough to not be in the way, without having to change the cross properties one by one?

Or perhaps there is a way to create layers, so that the crosses are on one layer, and the curve on another.


A second issue is that a couple of the points do not seem to be entirely accurate, and seem to distort the curve a little bit. 
Would it be better to simply delete that particular point, or is there a way to drag that point around a bit so that the perceived distortion is adjusted out of the curve.

Thank you!
Jamie


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* December 25, 2009, 11:33:48 AM
#5
Is there a way to select all the crosses at one time, so I can make them small enough to not be in the way, without having to change the cross properties one by one?

Or perhaps there is a way to create layers, so that the crosses are on one layer, and the curve on another.

Press Ctrl+T, which opens the "Select by Entity Type" dialog, scroll down the list to "Point" and click that entry, then click OK. The dialog will close and you'll find that all Point objects in your drawing are selected. While they are still selected, you can either open the Properties dialog and change their characteristics en masse, or create a new Layer and place them thereon -- or both.


A second issue is that a couple of the points do not seem to be entirely accurate, and seem to distort the curve a little bit. 
Would it be better to simply delete that particular point, or is there a way to drag that point around a bit so that the perceived distortion is adjusted out of the curve.

Select the curve, right-click to open the Local Menu, and select "Edit Tool" (might be called "Edit" in some TCad versions). You'll see a bunch of little blue squares and maybe some green ones, depending upon what kind of curve it is. These are all nodes, which you can click on and drag to adjust the shape of the curve. Press Esc or the Spacebar to exit the Edit mode.

If the curve is a Spline by Control Points, you'll probably see that it doesn't pass through all your Point objects anyway; adjust it with the Edit Tool to make it do so if you wish.

Henry H

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