# Thread: How to Draw This?

1. ## How to Draw This?

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Can someone please tell me how to draw a continuous curve like below pic (the blue curve) start from point A through point B and end at point C.

The one I had drawn on above pic is not continuous at point B. It's like a two different curves, the A-B curve and B-C curve, joined together at point B.

2. There are a few ways to get that done, but the important point is if you want it to be continuous the two arc centres should be on a straight line that passes through the tangent point. I placed the yellow dashed circles first to find the lower arc's center point, that gives you 2 points for drawing the straight green line, then you just have to find the point on that green line for the upper arc.
Tan.jpg
And this way starting from the top arc
Tan2.jpg
The dwg is for the first method, I'll let you figure out the points for the second

3. Originally Posted by steven-g
The shape of B-C arc is not what I want.
The shape is too concave.
As you can see, the B-C arc intersect C-E hidden line at D and C-D arc is exceed the C-E hidden line.
This is not what I expected.
The one I expect is that the B-C arc does not exceed the C-E hidden line.
From what I see is, you draw the A-B arc first than next you draw the B-C arc.
What about if I draw the B-C arc first then next the A-B arc?
Can you show me this method by an image like above?
This is the dwg file for you.

4. Use the same method as the first option if you use the ray command pick the start point as the center of your arc and the second point is B, then the center of your arc AB is somewhere on that line.

5. It is easy enough to draw continuous arcs, but there are many solutions to the measurements shown in your diagram.

You need to give more information or another dimension to get it how you want it to look.

6. Originally Posted by eldon
It is easy enough to draw continuous arcs, but there are many solutions to the measurements shown in your diagram.

You need to give more information or another dimension to get it how you want it to look.

The blue arcs is the same as steven-g made, no.

The shape of magenta arcs is weird.

The green arcs is my best choice.

Can you show me how to make the green arcs continuously?

7. Originally Posted by basty
Can you show me how to draw the green arc?
How about you follow the advice that was given first? "You need to give more information or another dimension to get it how you want it to look."

8. I offset the top line upwards by 1 (the actual offset distance is not important) so that point A is vertically above point B. This ensures that the tangent at B is vertical.

Now draw a line from A to B. End the line command and start the arc command. When the start point is needed (look at the command line), just press Enter. The arc will now start drawing from B with the tangent vertical. The endpoint of the arc is point C. Start the arc command again, and again when it says "Specify start point of the arc", merely press enter. A new arc will start, tangential to the previous arc. The end point is D.

Erase the temporary line AB.

9. Originally Posted by ReMark
How about you follow the advice that was given first? "You need to give more information or another dimension to get it how you want it to look."
All dimensions were already provided in post #1.

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Originally Posted by eldon
I offset the top line upwards by 1 (the actual offset distance is not important) so that point A is vertically above point B. This ensures that the tangent at B is vertical.

Now draw a line from A to B. End the line command and start the arc command. When the start point is needed (look at the command line), just press Enter. The arc will now start drawing from B with the tangent vertical. The endpoint of the arc is point C. Start the arc command again, and again when it says "Specify start point of the arc", merely press enter. A new arc will start, tangential to the previous arc. The end point is D.

Erase the temporary line AB.

Can you show me how to draw these green arcs by graphical method like steven-g did in post #2?

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