Bolts need length

[David Harrington]

Hi folks,

If you have a second I would appreciate a little formula insight. I need a formula that will drive a family for the length of a bolt.

So I have a bolt length (not including the head) and I have a thread length. Now the thread length can equal the bolt length or be smaller. It cannot be longer.

I must be missing something as I can’t figure out how to do the if statement that allows the thread length to equal or smaller than the bolt length.

Is this making any sense?

Any help would be appreciated.

[Steve Mintz]

If I understand correctly, you have the following parameters:

Thread Length: The parameter driving the length of the threads
Computed Thread Length: The result of some calculation (or label to a shape handle) specifying the Thread Length
Bolt Length: The length of the bolt

And you’re looking for a formula which looks like:
Thread Length=IF(Computed Thread Length <= Bolt Length, Computed Thread Length, Bolt Length)

But as you discovered, <= does not exist in Revit. However you can do the following instead:
Thread Length=IF(Computed Thread Length > Bolt Length, Bolt Length, Computed Thread Length)


I've attached a file demonstrating the above procedure (Method 1), as well as another option which provides obvious "feedback" to the user that what they want, cannot/should not be done (Method 2)


Speaking of "Should not", I sincerely hope you are not planning to model the bolt threads

[David Harrington]

Thanks Steve.

That assistance along with your many papers makes the issue pretty clear.

As for what I am doing, no, not modeling threads. But I could I suppose...

Nope, I'll stick to a 3D bolt family that just has the various types, washers, nuts, and controls for proper grip and length allowances.

[priitl22047477]

The topic became interesting for me when you started talking about bolts.
Sorry for being off topic.

How you model bolt holes or do you?

My way: I use symbolic lines in bolt family. So for views (steel beam shop drawing) that I only need holes, switch the detail level to that has no bolts. And then I have holes in the right place. If i move or change bolt then the holes are updated as well.

I am curious, maybe you have better way?