Partial Arc Lengths...again!

[isaacc]

I'm posting this again because nobody, even our reseller's support team and Autodesk support can't figure it out. Really, nobody has a response to this problem. So, here is another instance of the "Arc lengths are impossible sometimes" problem. When I want to do a partial arc length (viewport or viewbase doesn't matter), which is very often, they always snap in the opposite direction. I have turned all snaps off and anything I can think of that would interfere with the placement of these dimensions. Here is what happens: I click the arc length dimension button, it asks me to pick an arc. I pick the arc and type P and space for "Partial" to do a partial arc length. This is the crazy part... I shows me the measurement and I can move it around freely to place it anywhere I would like. The problem is, when I actually put it where I want it and click the mouse, it always goes around the other direction! It shows me the length as if it were a full circle and I wanted to know the length of the whole thing except the small section I selected. It doesn't even work if I do a full arc length and try to modify it to only show the partial. In addition to this, sometimes they will be perfect but I can move the dims and viewport/viewbase and they will all snap opposite! See the attached pictures. One is before I click to place and one is what happens after I click.

[nestly2]

Can you post the portion of the drawing shown your screencaps (including the dimstyle)

[Charles_Shade]

So this is what you are seeing happen:

 

[isaacc]

Pretty much, that's what happens. But, it always works in model space. Also, I don't resize them like that. I do partial and pick the points, it shows it fine until it clicks there and it snaps all the way around. I just want it to actually go where it shows it will go. Here is the DWG

[dbroad]

It depend on where you pick the dimension line location. If you pick outside the extension lines, you should get the long arc. If you pick between the extension lines, you should get the short arc.  At least that is what happens when I try.

[nestly2]

Like dbroad, I don't have any trouble placing the DIMARC text where intended.  I am curious what method you are using to pick the points since your dimension that's "flipped" to the wrong side is only partially associative.

[isaacc]

I move the dimension where I want it, i.e. inside the extension lines. The problem is that while it shows the correct placement (inside the lines), when I actually click it always goes outside the lines (opposite). Like I said in the original post: I pick the Arc Dimension, I pick the line, press "P", press "Space bar", pick the end of the arc, pick the point on the arc where I want to measure to, move the number (inside the extensions) where I want it, it looks good so I click and it goes opposite. In the pictures I attached in the original post, the first is what it looks like, then the second is what happens when I click it. If I was clicking outside the extension lines, the dimension shows outside the extension lines. As for the associativity, I have no idea what's up with that. Only about 50%, if that, of my dims are associated...on any drawing.

[steve216586]

The trouble is with the size of the arc length you are trying to dimension. It is not just the arc length dimension, any dimension would place the text on the outside. Try it on a longer arc length and I bet you don't have a problem.

[isaacc]

Please look at the pictures in the original post. I don't care if the text is inside or outside or wherever the program wants to place it, that's not the problem. The first picture (one where it shows the number value) is where it shows the text going before I click. It's fine that way, I understand the text will be outside the the lines because it is so small. But, that is not where it goes after I click. It goes opposite like the second picture. I need it to measure the arcs I pick, not the entire non-existant circle except for the arc I pick. Any ideas?

[steve216586]

"I need it to measure the arcs I pick, not the entire non-existant circle except for the arc I pick."

I can't duplicate that problem.

[nestly2]

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@isaacc wrote:

As for the associativity, I have no idea what's up with that. Only about 50%, if that, of my dims are associated...on any drawing.

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I did it about 20 times both on your drawing and my own, and only once did I experience it "snapping" to the opposite side, and it happened when I was being intentionally careless about selecting the arc and the points to dimension.  What is the "116" dimension in your screenshots,  because I'm not finding any actual geometry, intersections, or working points that are exactly 116 units radially along the arc in that area.  This goes back to my previous inquiry about what Osnaps you're using for the endpoints of the dimension, and also why your dims are not associative.

[isaacc]

Thanks for checking it out! Try this: I have attached pictures of each step. So, try to measure from the end of the arc at the bottom (it's around 6.2mm from the end of the tube) out to the center point of the diagonal tube. This what we do when building the item, the welders will measure from their tube clamp out the arc length and make a mark to line up the center of the diagonal tube. This measurement should be what it says before you click it, but for me it never works. Not even one time.

[dbroad]

Partial Dimarcs can never be made associative.

See video for how to dimension your drawing in paper space.

This video demonstrates how to fix your misplaced dimension.

[isaacc]

Thanks for the videos, but that dimension I do not have a problem with. It is the dimension I gave directions to:

Somebody already posted the video here on how to fix one that is flipped around. Please try the dimension I have shown above.

[nestly2 · Accepted solution]

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@dbroad3 wrote:

Partial Dimarcs can never be made associative.

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I'm not sure I agree with that (see video)

  I think the problem the OP is experiencing is because the points selected are not coincident with the selected arc.  In the first part of the video,  I can replicate the problem by picking the endpoint and the "center" of the tube.  The dimension flips and become partially associative as described by the OP.  However when using Endpoint and the Intersection of the arc and the line representing the centerline of the tube,  the dimension is placed where expected and it is associative.

http://www.screencast.com/t/Rv45E9dgH

[isaacc]

Awesome! That's exactly it!  So, when I pick the points, the point has to be associated with the line. It makes sense because the center of the tube is not really touching the arc, so picking the apparent intersection it associates it! Sweet!

[nestly2]

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@isaacc wrote:

Awesome! That's exactly it!  So, when I pick the points, the point has to be associated with the line. It makes sense because the center of the tube is not really touching the arc, so picking the apparent intersection it associates it! Sweet!

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Well, I can't say I use DIMARC very much, and even less when I use "partial" but yeah, it makes sense to me that the dimension endpoints would have to be coincident with the arc being dimensioned (even though AutoCAD doesn't actually "require" that they are)

I learned something new here myself  🙂

[dbroad]

The partial dimarc might report full associativity but IMO, it is a false report.  Even the tiniest change in an arc can disassociate the dimension from the arc.  So what is the associativity really worth?

A full dimarc is much more robust.  Partial dimarcs are too fragile for reliable associativity.

See:  https://chronicle.autodesk.com/Main/Details/c7548094-37b1-4b7d-aedb-11c78223d8f4

[ivovelickovski]

hello, can somebody hepl me and explane how to create continue arc lenght ???