Circular Array Parameters

[raymondjdawson925863]

Can anyone explain how to set a parameter for the radius of a circular array? I am building a circular table family that has brass buttons arrayed around the outside edge of the top. I can add the parameter to the number of arrayed items but when I flex to a larger table diameter I need the array diameter to change as well. Thanks

[damon.sidel]

I just tried a test: after you create your circular array, select one of the objects in the array and the arc that defines the array shows up. Click on the arc and it should give you some arc-length and a radial temporary dimension. Click on the symbol to make the radial dimension a real dimension, then turn it into a parameter. Should flex for you. If the radius of the array is different than that of the table, just create a new parameter and give it a formula to relate to the table's radius. You could even relate the number in the array to the radius. Finally, if you haven't already, make your brass button a separate family and nest it in your table family for better performance.

[raymondjdawson925863]

That worked perfect. I am having a hard time writing my formulas. I am new to writing the formulas. I am thinking I want the number of buttons to be a function of the distance of the radius. So I can tie the number of buttons to the radius of the array and the radius of the array to the radius of the table top. That way I only have to change table top radius and it all fits...Am I looking at it in a good direction? Thanks

[damon.sidel]

Yes, that's exactly right. Let's say you have three parameters:
Table Radius
Buttons Radius = Table Radius - 3"
Number = Table Radius / 12"
See if that works for you.

[Alfredo Medina]

If it helps, I just wrote a blog for another topic, (parametric polygons) but it explains how to control the radius and the number of items of a radial array. The blog article is at :

http://planta1.com/forum/entry.php?7-Easy-parametric-polygons-in-Revit

[raymondjdawson925863]

I am able to set a parameter to the radius and I have connected that parameter to the table so it moves perfectly. The problem I can't solve is to get the number of buttons to change with the radius. The formula I am using for number of buttons is =radius * 20. So if the radius is 3 feet I get 60 buttons all the way around. But because radius is in feet it has an error because the units don't match.

[damon.sidel]

I think you should be able to just say =radius * 20/1' to make it unit-less.

[jsteinhauer]

Raymond,

If you want the number of buttons to be calculated by the size of the table your formula would look like the following formula examples. You need to calculate the circumference of the table and divide that by the diameter of your buttons. You may want to build in an instance parameter to tweak your formula if it doesn't look correct.

#_of_Buttons=(Pi*Table_R^2)/(Button_D)
or
#_of_Buttons=(Pi*Table_R^2)/(Button_D)+Button_Tweak

#_of_Buttons = Integer Parameter
Button_D = Dimension Parameter
Table_R = Dimension Parameter
Button_Tweak = Integer Parameter

Hope this helps,
Jeff S.

[damon.sidel]

Jeff,

Those formulas will definitely give you better control over the number of buttons around the table. Don't you still have to divide by 1unit? For example, let's say:

Table_R is in feet
Button_D is in feet
#_of_Buttons=(Pi*Table_R^2)/(Button_D)
#_of_Buttons=(Pi*feet^2)/(feet) will be in feet

Raymond, I'd definitely use Jeff's formula, but divide the whole thing by 1foot to make it unit-less.

[jsteinhauer]

Technically yes, because you are squaring the Radius, and the one division for the button Diameter would not cancel out the square. If you have one unit of length and divide it by another of length, it should work without the additional division of 1'. This works for any unit of measurement, not just length.

Still having trouble getting Revit to use Pi in formulas. Any help out there on that?

Jeff S.

P.S. Do any monitors out there think this thread should go under the families forums instead?

[Alfredo Medina]

...Still having trouble getting Revit to use Pi in formulas. Any help out there on that?


It is strange that you don't remember about Pi, since the answer is in this other thread that you started some time ago: :)

http://forums.augi.com/showthread.php?t=112384

[jsteinhauer]

Missed that one. Must have gotten buried when I wasn't looking... PI() got it. Thank you Alfredo!!!

Jeff S.

[zbrown]

If it helps, I just wrote a blog for another topic, (parametric polygons) but it explains how to control the radius and the number of items of a radial array. The blog article is at :

http://planta1.com/forum/entry.php?7-Easy-parametric-polygons-in-Revit

Thank you this post was very helpful. It helped with a lineat array problem that I was having.

[Alfredo Medina]

Thank you this post was very helpful. It helped with a linear array problem that I was having.

Thanks. I am glad to know that my blog article was helpful.