# Another Boolean union question

This is a link for a necklace I am working on. The parts consist out of stainless steel, riveted together with gold rivets.
In order for me to be able to do a proper “Flow along Curve”,

I have to do a Boolean union of the parts, otherwise this happens. In this example the parts are in a Group.

You can see the major distortion of the individual steel parts very well in the top link. The three steel parts are supposed to be in a straight line. The gold rivets are also slightly out of place.

When I do a Boolean union of the stainless steel parts, this distortion does not happen and all the steel parts stay straight, the way they are intended to. The gold rivets are still slightly out of place.

When I Boolean union the gold parts to the steel parts, the resulting part is either all gold or all steel. I have not been able to avoid one or the other from happening.

My question is, is there a way to do a boolean union so the individual parts keep their characteristics, or is there a way to glue them (a term from my previously used 3D modeling program), or group them together, so that when I do a Flow along curve this distortion does not happen.

A very quick test with a rather simple models seems to indicate that this works if you turn the link into a block and copy the block.
(but it might have something to do with the settings in the flow command as well, I suppose - have you played with these?)

Try the Flow option Rigid = Yes to keep the links from deforming. Also Record History to be able to update the target curve or the base link spacing for adjustments.

I do not quite understand what you mean with this. Do I first take the link and turn it into a block, and then copy and paste to make the chain. And then do Flow along Curve?

I can easily do what you show in your image without any distortion in the individual parts. Your example does not contain additional materials, only one material with elements that one can easily boolean union. I have three different materials that seemingly I can not do a boolean union with. The red sphere is obvious of course, because it does not intersect with the other parts.

As far as Flow settings are concerned, I used the Rigid option, otherwise all the links in the entire chain curve. However since I cannot boolean the gold parts the the steel parts without losing one or the other characteristics, the placement of the gold parts gets distorted. I forgot to mention, the placement of the red spheres is also wrong in many places after Flow. Because of movement the steel parts go right through it.

a longshot but it might work

have you tried `ArrayCrv` on a single necklace component?

it should array the component along the curve at a spacing of your choosing without the deformation.
that said, i don’t know whether or not you’ll be able to get them to interlock properly through various bends.

Yeah, I guess we need a ‘respect groups’ option if Rigid=Yes - but the Block workaround is a good one for now- the block instance is kept intact as a single object.

http://mcneel.myjetbrains.com/youtrack/issue/RH-29990

-Pascal

Yes. You turn one complete link into a block, place copies along each other to make a straight chain and then flow.

The block command worked! Thank you. However Record History does not seem to work in order to center the chain nicely around the curve.

This is what I did. I first clicked history > Pick the chain > Flow > Choose Base Curve > Target Curve. As soon as I choose the target curve History dims in the top tool bar, and Curve Edit Tools > Adjust Close Curve Seam does not work to pace the chain.

That’s odd, it works here as shown in the attached file. I am using 5A751 and tried it with history on a curve and also a deformable circle. The command CrvSeam allows the seam of the circle to be changed and the flow updates. Maybe there is something different about your target curve. Try it with a box block like I did and if it still doesn’t work, please upload the file here and I’ll try it as well with the same geometry.
flow_history.3dm (79.3 KB)

I downloaded your sample file. The same thing happens. The moment I click the target curve, the History highlight turns off on the tool bar, and adjusting the seam does not reflect in the geometry of the parts.

I am working in version 5A713. I did not want to work in version 5A751 yet, because of some rendering I have done with Toucan, and I’m not ready to completely relearn rendering with Rhino Render yet.