Constraints

[dtiemeyer]

Is there any way to constrain the distance between 2 objects.  I have multiple lines routed in parallel 12" apart. I would like to be able to pick one grip and shift the entire lot of them. I don't see a constraint for that. Am I missing something?

[john.vellek]

Hi @dtiemeyer,

Have you considered using an ARRAY for this?"

Otherwise you can set this up for two points at a time but I don't think that will be very efficient.

Please select the Accept as Solution button if my post solves your issue or answers your question.

[dtiemeyer]

AFAIK array does not allow the lines to be on different layers, which is necessary.

[john.vellek]

Hi @dtiemeyer,

Perhaps change your lines on multiple layers to a dynamic block.

[dtiemeyer]

Then they cannot be filleted, trimmed, etc.  This is for a piping layout with multiple different piping systems needing differing layers, as well as different lengths, the ability to be broken (for valves,rises/drops,etc). All I really want to do is be able to lock the distance and maintain a parallel relationship between 2 or more lines. I don't believe this is something the constraints can do, but I'm no master. Could you confirm they cannot do this?

thank you!

Dustin

[john.vellek]

Hi @dtiemeyer,

Two lines is easy. More than two is where the feature doesn't work.

For instance, start with two parallel lines. Then from the Parametric tab, you can select AutoConstrain and pick the two lines. The constraints I got included vertical(since that is the original orientation) and parallel. So far so good. Then you can add a linear dimensional constraint. This however only allows you to select endpoints of the two lines (not more).

Perhaps someone in the customization forum has created a way to resolve this for you.

Please select the Accept as Solution button if my post solves your issue or answers your question.

[dtiemeyer]

Thanks for the follow up on that John. Actually you can then daisy-chain a 3rd line to the 2nd, and so on. But I noticed that that group (of lines and constrains) can be rotated, but the resulting behavior is wonky (technical term) and not as expected. It appears the dimconstraint is remaining in the orientation it was originally created, and not rotating with the elements it is meant to constrain. Bummer.

[beyoungjr]

You are headed in the right direction.

You can constrain line lengths and use the constraint manager to mathematically control one line to reference the other one (d1 constraint gets a value of =d2).  You can also use the = (equals constraint to have one line equal another or even one circle equal another.  Try creating a constraint to force the endpoint of one line to be horizontal to the endpoint of the other line (both lines having a parallel relationship already).  Also, instead of parallel you can let each line itself be horizontal or vertically constrained (this would really screw up rotating though).

I think you might find some good options in experimenting with the constrain manager.  You can control objects using expressions.  You can get crazy and control several object's relationships.

Many good references to help you dig as deep as you like but here's the starting point that I point students to after we cover the quick & dirty details in class.

                  @ the ACAD Knowledge Network

Good luck

[john.vellek]

Hi @dtiemeyer,

I am checking back to see if my post or @beyoungjr's helped you with your problem. Please add a post with how you decide to proceed and your results so other Community members may benefit.

Please hit the Accept as Solution button if a post or posts solves your issue or answers your question.

[dtiemeyer]

Hey John,

I was never able to get this working efficiently. I know my users will think it's too cumbersome to re-create the dimension constraint for every situation. If it could be copied and rotated in a way that the results cause what the users would anticipate the behavior to be, then it might be useful. Unfortunately I'm using AutoCAD MEP which doesnt seem to have the Constraints tab, so everything I did was via Command Line, and I couldnt find the key-in to get the Constraints Manager as the other gentleman mentioned.  That being said, I just dont think it's intuitive enough that my users would adopt it.

Thanks though, for the suggestions. I'll keep an eye on developments in that area.

Dustin

[john.vellek]

HI @dtiemeyer,

I revisited this just now and I think it is faster to set up than I anticipated. I did not use the Manager component at all. I don't work in MEP so I don't know where he Parametric tools are located for constraints but i bet they exist somewhere (I will dig if you need me to find out).

I created two lines and assigned a parallel constraint to them. 

Then I added a linear distance constraint between the two lines.

So far so good.

Next I copied one of the lines and added another parallel constraint

When I add the distance constraint, I set the value to D1

I did this again and copied two lines this time.

The constraints were quick to apply

Again, I assigned the distance constraints on these lines equal to D1

I think you might want to revisit this too!

Please select the Accept as Solution button if my post solves your issue or answers your question.

[Anonymous]

How about a Dynamic block with a stretch parameter??

[beyoungjr]

Pretty much what I wanted to convey.  You presented it better than my description above.  Hope it works for him.

[marco_martinez · Accepted solution]

Hi @dtiemeyer,

Look at this, I think this is what you need

Send you the .dwg so you can check it out too

Tell me is there´s anything else you need so I can help you

[dtiemeyer]

thanks @marco_martinez  That is what I'm looking for! Using that option it does not apply any vertical/horizontal settings, only the dimension, and can be rotated.  Also a quick test shows that the constraints will go into blocks, so I can create typical 'starting point arrangements' for my engineers. Cheers!