[V8i/SS10] Place quarter ellipse tangent to something?

I could swear I used to do this, but I could also be mistaken.

Is it possible to place a half or quarter ellipse tangent to two lines?

Parents
  • I would suggest possibly using the Tangent Snap may be effective in performing this operation.

    Snap Mode Toolbox

    Regards
    Andrew Bell
    Technical Support
    Bentley Systems

  • Andrew, I am aware of the Tangent snap. It doesn't work for half or quarter ellipses - go ahead and try it.

    When I place an arc, I have the option to place it "Start, End, Mid" which allows me to snap tangent to the first line and tangent to the second line. This gives me a dynamic arc that I can "pull" about to get the arc I want. I use this often to create an arc that approximates a line string that looks like an arc, but is a bunch of tiny segments around a corner.

    There are no options - none - for placing a quarter or half ellipse. And the snaps don't work in the same way.

    The first prompt for a quarter ellipse is "enter one end of the ellipse quarter". Right here, I know I am in trouble. I don't know the specific point for the end of the ellipse. I only know that I want the ellipse tangent to this element over here. I can use the tangent snap if I like, but the point accepted does not save the tangency constraint. It only uses the location, not any tangency.

    The next prompt asks "enter point on axis". This is essentially looking for the center point of the ellipse. I don't know that, because i am looking for something more dynamic (like the arc). But I can enter a point, just to move on with the exercise.

    The third prompt is "enter endpoint". I do have a semi-dynamic element, fixed at the first point and the "center" I chose. At this point, I can't use the tangent snap. It's not allowed. I have the little "no" symbol over the top of what would be my snap.

    I don't use this tool often, and I can see why. I hope I am missing something - some step, some setting, getting the prompts wrong?
    Perhaps I am remembering the tool wrong and it was never possible to create tangent half/quarter ellipses and I did something else instead...

    MaryB

    Power GeoPak 08.11.09.918
    Power InRoads 08.11.09.918
    OpenRoads Designer 2021 R2

        

  • Hi Mary,

    It's quite simple to do, you just need to think about the task differently because the tool dictates the task. Tangent Point Snap doesn't work for this task so just stick with Key Point Snap.

    To do it:

    1. Draw your Tangent Element (linear element works best)
    2. Activate the Ellipse tool and snap to an end-point of the element.
    3. Left-click to set the first point of the ellipse
    4. Select Accudraw and press R then E, hover the line and left-click.
    5. Now pull the cursor perpendicular to the element and (optionally press Enter to engage smart-lock) left-click to set or type the primary axis value
    6. Finally set the Secondary axis value and you will have an half/quarter ellipse that is tangential to the first element.

  • great but  how do you do it to two existing  lines?

    Lorys

    Started msnt work 1990 - Retired  Nov 2022 ( oh boy am I old )

    But was long time user V8iss10 (8.11.09.919) dabbler CE  update 16 (10.16.00.80) 

    MicroStation user since 1990 Melbourne Australia.
    click link to PM me 

  • The longer I think about it it seems there's something overlooked. A quarter ellipse needs two lines being rectangular to each other. Therefore there's no need for a second tangent.

    I guess you'll need to draw parallel lines to find the center of the ellipse and then go ahead.

  • But a quarter ellipse could be tangent to two lines with floating endpoints, as in, I know I need an ellipse tangent to two lines, but i may not know what the axis lengths need to be. This means that I don't know the exact points to click. It would also be possible for a quarter ellipse to be tangent to a line, just not at the quadrant.

    From time to time, i need to draw fillets with unequal scaling. I work in drawings that may have an exaggerated vertical, like 1H:5V. There are a few ways to place fillets like these, but I thought that placing a quarter ellipse might be a faster option:

    I had to draw this quarter ellipse off to the side and move it into place because I can't wrap my head around the calculations to figure out where either endpoint is. Even now, I'm not certain if the ellipse is actually tangent to the slanted line because I have problems getting "Move to Contact" to work the way I expect, but that's another discussion for another time.

    It's OK if this can't be done with the tools as they are. As I said, I have other ways of constructing what I need. 

    MaryB

    Power GeoPak 08.11.09.918
    Power InRoads 08.11.09.918
    OpenRoads Designer 2021 R2

        

Reply
  • But a quarter ellipse could be tangent to two lines with floating endpoints, as in, I know I need an ellipse tangent to two lines, but i may not know what the axis lengths need to be. This means that I don't know the exact points to click. It would also be possible for a quarter ellipse to be tangent to a line, just not at the quadrant.

    From time to time, i need to draw fillets with unequal scaling. I work in drawings that may have an exaggerated vertical, like 1H:5V. There are a few ways to place fillets like these, but I thought that placing a quarter ellipse might be a faster option:

    I had to draw this quarter ellipse off to the side and move it into place because I can't wrap my head around the calculations to figure out where either endpoint is. Even now, I'm not certain if the ellipse is actually tangent to the slanted line because I have problems getting "Move to Contact" to work the way I expect, but that's another discussion for another time.

    It's OK if this can't be done with the tools as they are. As I said, I have other ways of constructing what I need. 

    MaryB

    Power GeoPak 08.11.09.918
    Power InRoads 08.11.09.918
    OpenRoads Designer 2021 R2

        

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