Using Constraints to Stretch multi lined arc.

Ok, so here is my delima. Hopefully I can explain this properly...

I have created a couple of dynamic blocks for profiled window surrounds for both a square top window and arched window. I have accomplished the square top window, but creating the arch top has proven quite difficult.

What I need is roughly the same setup as the square top, using the XY parameter set and entering the width and height so the window stretches accordingly, however on the arch top, I am needing to add a parameter to enter the "chord" dimension. I basically need another user imput parameter to facilitate the peak of the inside radius (currently shown at 4'0-5/8") in the attached drawing bordered by "DYNAMIC BLOCKS." I am not sure on which parameter to add to stretch the arch at the designated "arrow." and even once that is figured, how to make the arches that are stacked above it to stretch properly. I added Horizontal Dim constraints which seemed to work, however upon further review once stretched, the outer arch doesnt stretch properly (Review Example 1). It is supposed to be like "2" and "3". Basically as you offset the inside pline out 6" the intersection is supposed to adjust and not stay stationary.

Also on a side note, I added vertical constraints and Dim Vertical Constraints to the "legs" of the window profile because as the inside arch was stretched the legs would not produce logical results.

I dont know how else to explain it, but I hope someone can help.

WINDOW EXAMPLE.dwg

After messing around with your file, I've come to the conclusion that you are trying to do too much at once with the arch topped window. In your effort, did you try constructing a single line window with the parameters correct, then a 2 line window with the parameters correct, etc, slowly building up to the final 5-6 line window block?

[rambling thoughts...] Scale is used to keep an arc constant to the width. The other lines would be a set distance from the scaled line. If constraints are used to set constant distances, can you use an underlying frame (the critical points that need to remain constant to each other) on non-printing lines in your block and tie the arcs to that ?

I'm also left wondering...

-why isn't the base point for the stretch command on the center of the sill. The way you have it set up, you'll have to constantly bump a window over as it is centered on a particular wall. When ever I see plans, openings are typically measured to the center, and the width of the opening is its own measurement.

-is the arch a fixed distance compared to the width ? #2 and 3 don't really match...and if the arch isn't fixed to the width, how/where do you spec that to the window mfg?

I did try constructing a single line arch top window and it seemed successful (I was too hasty to actually put it in the Block Tester) so I decided to move forward. I didn't think about baby stepping through the process as I am a "learn by doing" kind of person. I have read a few guides and watched a few examples and thought I could...well...wing it. I should probably start back at the beginning and slowly move forward as you have suggested.

Regarding using the Scale parameter, I did not even think to try that yet. As I am still new to the Dynamic block, I realize how much of a headache it can be. I won't even get into the "don't know where to begin" question that I have once I can accomplish this step.

The reason the base point for the stretch command was at the center of the sill was more a direct thought based off of how I draw the windows manually...say I get field measurements in and the window measures 3'-0" wide, 4'-0" at the "leg" and 5'-0" at the peak of the arch. I would draw my width, put a leg on one side and mirror it, and draw a guide line from the midpoint of the width to the distance of the arc peak thus giving me my radius and rise.

Now for a back story on what this is for...I am a draftsman for a cast stone company that does various cast stone masonry for residensial and commercial buildings. The most common things I draw are rectangular window surrounds and arch window surrounds. My goal (which I was mostly able to accomplish with the square window dynamic block) is to speed up the process of the standard windows so I can focus on the more complex cast stone entries.

The multiple lines you were wondering about will make more sense once you see the pictures I have attached.