Hello everyone. Today in class, the teacher gave us an assignment. Let’s try to connect 2 red lines with height d = 0.5, but without using the green curve. I did some research and found out that there is a script (paid) that can do this. However, is there any tool on RHINO that can do this quickly? Please help me. Thanks.
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Are you asking for someone to do your assignment for you?
No. No. I am trying to find a way. I can only do it with the blue line. As for the 2 red lines I still don’t know how to do it. I tried using 2 edges to fillet but the teacher still said it was wrong.
Just draw a line with snapping on from the tip of one red curve to the tip of the other red curve, then they are “connected”.
There are several, probably lots of, ways to do what you ask. I suggest you think about what you were being taught in the lesson when this task was set and see if that material can be applied to the problem.
What is the deadline for submitting your answer?
Unfortunately you have missed the height (sic) criterion…
(Please don’t take this as a challenge to do the OP’s homework for them!)
Sorry, I seem to have expressed myself a bit poorly. I understand how to draw the blue line and use the sweep connection curve very simply. However, the exercise is: In RHINO, can you connect the two red lines with an arc d=0.5 without drawing any other lines? (Only 2 red lines and no 3rd line allowed)
Deadline is 10/6/2026. Connecting and drawing an additional line is very simple. I can do it completely. But the score for the assignment is not high. The teacher needs someone who can do a method to connect those 2 lines with a certain height. But drawing additional lines is not allowed. :(. I have studied a lot of videos on Youtube and forums but most of the popular ways people use are drawing additional lines. This way anyone can do it.
I am thinking that instead of drawing additional lines, I will use a surface to fillet.
if this is about drawing in Rhino and learning the drawing aids, then you should look into Smarttrack and Osnap
I don’t understand why people misunderstand that I asked everyone to do my homework for me. My classmates and I have discussed with each other (including the seniors) and they still don’t know how to do it. For a beginner with software with too many commands like RHINO, it is really difficult. 
You need to find the radius point of the top of the 0.5 curve use the command _MarkFoci to find it. Then do a surface revolve using the radius point of the 0.5 arc as your revolve axis, use the red line as the line to revolve and then both lines as start and finish points.
RM
You’re still not expressing yourself clearly enough… What do you mean by “connect” ? Connect the line ends with an arc curve? Connect the two lines with an arched surface between them?
Arc with 3 point option?
It’s easy to find the center of the arc, then the vertical arc surface could be created either by extruding the arc itself, of revolving one of the vertical lines.
But sadly you aren’t following the rules:
Let’s try to connect 2 red lines with height d = 0.5, but without using the green curve.
I followed the quoted rule from the original post. But even if it’s prohibited to create any new curve, the same operations shown in my video could be made by using SmartTrack. No big deal. 
In case that the 0,5 mm line could be used as a reference to snap to, then a line (or a temporary projection vector with SmartTrack) could be created starting from the former until it reaches the opposite vertical line. Then the middle of the line (or the temporary vector) could be used as a 3rd reference point to create an arc with the ! _Arc _StartPoint or ! _Arc _StartPoint _Pause _ThroughPoint tools.
An alternative is to create a line between both vertical lines, then create a 0,5 mm lone from the middle of the first line and use one of the aforementioned arc tools to create the 0,5 mm tall arc.
Maximise the front view. Zoom to max out the two vertical lines. Take a large set square and a sharpie, and draw a horizontal line on your screen. Carefully snap start and end of the arc to where the lines intersect.
If I understand correctly, there is a radius associated with the circle that has a chord with midpoint that is d=0.5 away from the perimeter of the circle. Using that radius and the proper Arc command the desired arc can be made without using the green arc or the line. I’m not going to reveal what that radius is since it seems to be part of the assignment.
If you cannot draw any construction lines then you need to turn to geometry to calculate the radius of the arc:
r = h/2 + w^2/8h
where h = arc height = 0.5 and w = distance between red lines = 2.018.
You can then use the arc end, end, radius tool to construct an arc if that is what you need or cylinder three point (using the radius option for the third point) if you need a surface, then using the red lines to trim the cylinder.
Hi
I couldn’t figure out what the op wanted, I thought he wanted a surface which I expressed how to make without any additional lines. Interestingly the guy in the video does it similarly to what I came up with. I thought it was funny he has grid snap on, and if one has different snap settings this way won’t work, though you could move the point manually.
Also you could use “arc start end radius” and use smart track to find the point where they intersect diagonally.
Bobi used a revolve too which was my first guess. I opt for the construction lines technique to get the job done better to be safe than sorry. I don’t trust smart track or shortcuts like this. One needs to be sure and to have a way to check your work.
RM
