Cyclical constraint dependency detected?

[Denimoth]

G'day all!

 

So I made the jump to Inventor and started working on a small project. I have had no formal training in Inventor, but had some training in Solid Edge several years ago. Still, I'm fairly confident that I can do the majority of what I want to accomplish. Now I've bumped into a problem that has me stumped to figure out the answer. Hoping someone could offer some assistance here.

 

I'm trying to draw a sketch that will represent my vertical post locations for a railing I'm designing, with the intention of using frame generator to create the 2"x1/2" flat bar posts. I have drawn some construction lines to represent the top and bottom of my posts, and have now drawn 7 lines that are going to be my posts. I've constrained the line that make up the left most post and did the same for the right most post. No problem so far. Now I need to evenly space the 5 lines in between. I drew a dimension of both constrained lines, the dimension is a driven dimension (d26) which is fine. I'm using it for a reference. I'm now trying to dimension the lines in between to give it the equal spacing I'm looking for. I add the formula d26/6 (take dimension d26 and divide by 6) and an error pops up that reads as follows: |A cyclical constraint dependency was detected."

 

First of all, what is causing this error message? I'm pretty sure I have my constraints properly set up (but I've been wrong before).

 

And second, how do I go about creating equal spaces for my vertical lines if I can't dimension it?

 

I'm making it so that if I need to change something to the structure, my railings will adjust accordingly, hence why I'm trying to reference a driven dimension.

 

Anyone able to help me figure this out?

 

Thanks in advance!

Assembly.zip

[kencaz]

Can't open your file only have 2009 however, you may want to try a fitted array...as such:

 

 

KC

[Pablo Ferral]

Check out this tip from Garin Gardner:

http://inthemachine-autodesk.typepad.com/blog/2008/06/evenly-spaced.html

[Denimoth]

Thanks for the suggestions. I will have to try both ways suggested and see what I learn from that. I managed to get the spacing done on my drawing, but had to place another driven dimension between fixed points in the geometry, and then complicate the math formula a bit by adding and subtracting the other 2 dimensions that constrained the lines at each end of the ramp, and then dividing the sum of those into 6. It's basically doing the same thing that I was trying to accomplish before, but for whatever reason, inventor accepted the new driven constraint but still gave me the same error when using the original driven dimension. Weird...

 

And sorry for not mentioning I used Inventor 2010.

[kencaz]

Check out this tip from Garin Gardner:

http://inthemachine-autodesk.typepad.com/blog/2008/06/evenly-spaced.html

 

That just seems like more work to me...

[Pablo Ferral]

It depends on the situation. If I know how many items I need and I just want them to be equally spaced then I happily use the method outlined in Garin's Blog (or geometry with Equal Constraints). If I don't know how may element's I need, but I know what spacing I want, I will use patterning. However I prefer not to pattern sketches because it's really hard to edit them without messing everything up. In the case above I would pattern the Part - not the sketch.

 

It maybe more work but It leads to more robust model, so less repair work down the line.