Make a coil follow a path

[Bruce Kieffer]

I'm trying to model a spring that follows a path. This is an exercise for our user group's 5th annual Solid Modeling Challenge. The spring is in a stapler, and it travels straight for 1-1/2", then turns a slight curve, and then goes straight for 1//2". The angle of the long section is 20° relative to the short section. The curve between the two sections is about a 1/4" radius. Any suggestions how to model this?

[AlanW]

Do you need to use extrude along path for the whole object??

Because the sweep command will create a great spring then just use EAP for the other bits and then Add Solid it all together.

Edited January 11, 2016 by Alan Woodwell

[Andy Broomell]

What about creating a straight spring then using the Deform tool from the 3D Modeling toolset to add the bend?

Edited January 11, 2016 by AEB

[Benson Shaw]

Bruce, can you post a photo of the spring?

AEB's idea could work.

I twisted an extruded circle for the coil. It flattens the profile, so EAP would probably be better choice. Controlling the bend could probably use a better guide object than my center cylinder. But, just tried it for fun!

-B

Edited January 11, 2016 by Benson Shaw

[AlanW]

Is this what you are after?

What i did was create the spring with the sweep command then extracted the curved line using the extract iso-parametric curve (3d tools extract) then added the additional lines and joined them and then EOP to get this narrow coil spring.

HTH

Edited January 11, 2016 by Alan Woodwell

[Bruce Kieffer]

Benson, Here's what the spring looks like with the cover partially open.

Spring in Partially Open Stapler

I will try the deform tool. Thanks everyone for the suggestions.

[PVA - Admin]

Deform in Bend mode should work, just make sure to disable "Symmetric" mode near the end of Deform's tool bar. Otherwise you wont be able to make that bend in just the end it would try to bend the whole spring from end to end.

[Benson Shaw]

Ah, Now I understand the shape. The bend tool will form it. The closed position of the stapler lid would deform the spring even more.

So, it's worth trying to model this with a straight spring made from a Sweep with pitch (pitch value = wire diameter plus a little extra) or an EAP of a helix. Then bend with the deform tool.

If the bend at a finite length is too sharp, break the coil into segments and apply the symmetric mode to the portion needing a bend.

Anyway, I'm looking forward to seeing the assembled model with components from your user group!

-B

[Benson Shaw]

OK, Now I'm miffed. The Deform> Bend tool apparently cannot bend lots of objects. I tried lots of base objects: Sweep (pitched), Expansion Spring, Helix (3d Power Pack), an EAP of the helix, A NURBS conversion of the helix, and the various ungroupings, extracted edges, etc, etc of those higher level objects. I also tried different combos of the Bend modes on all the above.

The only thing I found that would model this bent spring is to make a twist of an extrude, bend the twist, extract the egde and EAP that edge. Whew!

Anybody else get this to work more easily or more predictably?

-B

Edited January 12, 2016 by Benson Shaw

[Kevin McAllister]

Benson,

That's a lot of leg work. Really it shouldn't be this difficult. Sounds like the Deform tool needs some improvements.

Kevin

[Benson Shaw]

Sympathy accepted.

Certain limitations of the Deform>Bend tool sort of make sense. For instance it would seem weird to bend a door or a window.

A bend in the coil requires spreading the outer components and, depending on the center of the bend, possibly compressing the inner components. That might present some difficulties in the programming, but somehow the tool manages to bend the twisted extrude.

I always thought NURBS curves were pretty mutable. But I couldn't bend a helical NURBS curve with the Deform>Bend tool. Generic Solid versions of the Sweep or the EAP were also unbendable in my trials. Most objects present a promising live preview of the bend as the spine and bend extent are dragged around on the drawing plane. But final click yields a fail message. Maybe there is some radius limit or other factor I missed.

This was a quite a challenge. For me anyway!

-B

[AlanW]

Hi,

Computer didn't like it but I created a helix spiral from the 3d power pack and I could deform this and then converted it to 3d polys and EAP. Computer said NO, but went black so left for a few moments and came back like this. Kept saying invalid path object if you move but does not fall apart but eventually stay like this.

The helix spiral is a good place to start then EOP.

The #3 is a Nurbs Curve and convert to a helix spiral then EAP.

Finally #04 is the easiest.

Simply draw a polygon with a few bends then vertexs to get a nice radius, then create a Helix spiral and use the polyline and then adjust the setting of the Spiral to get the desired shape.

Coil-04.jpg I think this was the simplest and the computer didn't spit the dummy. It was all very quick.

Explanation in short video here.

Edited January 12, 2016 by Alan Woodwell

[Bruce Kieffer]

Thanks for all the input. I will present these solutions to our group tomorrow night.

[Benson Shaw]

Alan -

#4 - Perfect! So simple and obvious. I forgot the helix could be formed from something other than a straight line!!

Regarding bending a helix spiral - My Deform tool will not recognize/select the helix (or a NURBS curve) to deform it.

I made another attempt at bending an existing coil EAP. Extracted the whole surface and converted to NURBS surface. Deform tool failed to bend it.

You mention converting the helix to 3d poly prior to EAP. I am able to EAP the helix spiral object without prior conversion to 3d poly.

-B

[AlanW]

Thanks,

Started with polygon and when you convert to helix the path becomes a Nurbs curve so later you want to change the path you click on spring and edit path then right click again and edit and you get back to the Nurbs curve. Moving the nodes around had some limitations which will not always allow you recreate and I am not sure but it could be to do with overlapping geometry after moving the path.

[PVA - Admin]

To all in this thread:

Please posts some of the sample objects that failed to Deform when you have a moment, Engineering wants them for tests.

[Benson Shaw]

Here is v2016.vwx file in Front view.

Spring PIO series on left. Helix PIO series in middle.

These all failed during Deform>Bend.

Twist series on right side, shown in screen shot above.

Twist formed a generic solid.

Deform>Bend successful on the generic solid.

-B

[mattOC]

Hi,

this has been a super helpful thread, thanks to all that have contributed. I'm in a situation where I'm trying to create a 1/4-20 internal pipe thread. I've been trying to master the sweep (as instructed in this thread https://techboard.vectorworks.net/ubbthreads.php?ubb=showflat&Number=135304) to no avail.

Anyone have another way of creating the an internal pipe thread?

thanks a bunch,

M

[AlanW]

There is a whole section in VW dedicated to engineering and nuts and bolts and threads.

Could you use something from here? it's a tool palette.

[mattOC]

Hi Alan

I'd love to, but those ( at least what I've found) are external threads. I need to create internal threads into a custom diameter rod.

[AlanW]

Hi,

Not near a computer to test this for a bit but what I would try is to get an external thread that I wanted and create a cylinder of the external pipe and place them together and subtract solid and remove the bolt, you should end up with a tube with an internal thread.

You may have to explode the bolt first to do the subtraction.

HTH

[Benson Shaw]

@Matt

This is Alan's suggestion with a set screw instead of bolt. No need to explode or convert the screw. Note that lots of these in a file can make the file laggy. So if many are needed, either convert the solid subtractions to Generic Solids, or make a symbol for every type, or convert & symbol.

-B

Edited June 8, 2016 by Benson Shaw

[Marissa Farrell]

The solid subtraction would also have been my suggestion.

(Other than Marionette, but that would be slightly more time consuming )