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## Closed and Ground Spring - Alternative to Helical Sweep

Edit 07/25/2014: Please see the linked thread for information on Wrap issues using some equation curves.  Another equation curve approximation error

A not so quick video on the technique of creating springs without fussing with the helical sweep and multiple pitch setting.

I found it difficult to create a good representation of a closed end spring, and also the closed and ground version.

This video shows how to make a closed and ground spring and how to quickly tweak it to the exact shape you want to show.

There are several techniques throughout this video, so don't miss the little detail...

• How to define the initial sketch finding the core diameter vs the known ID or OD.
• How to manage the known parameter.  In this case, the OD, height, and the wire dia. were all known's.
• Using the Coordinate system in the Wrap Section.  You might even opt for sketching in the section starting at the bottom of the cylinder.
• Using Pi*D*No. of Turns to manage the overall swap.
• Remembering to save the hidden layers.
• Tweaking the Wrap Section to maximize accuracy.

Of course, if you make a lot of springs, you want to use more relations to automate this process somewhat.

Hope you find this video useful.  Please -like- this document if you do.

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14 REPLIES 14

## Re: Closed and Ground Spring - Alternative to Helical Sweep

Hmmmm, somehow this looks real familiar......

## Re: Closed and Ground Spring - Alternative to Helical Sweep

Great minds think alike, Frank

## Re: Closed and Ground Spring - Alternative to Helical Sweep

What are the OD & ID?  I couldnt really understand what your doing with the Relations & Wrap command?

Length = .595

Material Dia = .048

Correct?

## Re: Closed and Ground Spring - Alternative to Helical Sweep

Sorry Kaci.  OD is outside diameter and ID is inside diameter.  I use the mean diameter as through the center of the wire diameter.  Most often, springs are defined by either the ID or OD.

Lengths for springs are free length (uncompressed)

Working range (typically the installed height in your assembly model)

and maximum compressed length (height).

A test of all these values will tell you if the model is robust or not.

## Re: Closed and Ground Spring - Alternative to Helical Sweep

I'm sorry, I mean OD & ID of this particular spring?  Also what does drawing the sketch in wrap command do?  So in the relations formula what exactly are we doing? Can you please break this down for me, sd21=((.804*6)*pi)?

## Re: Closed and Ground Spring - Alternative to Helical Sweep

I see what you are asking.

In extrude 1, I am controlling the OD of the spring at .9" and a wire diameter of .048" (1:30)

This leaves a mean diameter of .804" (ref dim).

The height of the surface quilt is .595"; the height I want the final part to be.  I extruded equal in both directions as a personal preference (1:40)

DTM4 is to help make sure the wrap is made where I want it.  You can make it on the center plane, but you cannot control the direction of the wrap from there.  (2:00)

The sketch for the wrap is internal to the feature (optional) and you see me place the coordinate feature 1st (2:25).  This is often forgotten but controls exactly where the wrap begins.  Otherwise, it can offset if the sketch is not symmetrical in any way.  Always use the coordinate system!

Then I align the ends to the quilt at 2:35.  This sets the height I originally defined with the quilt.

In order to make a spring closed and ground, the pitch changes.  This is controlled by the horizontal ends and the radius.  This may require tweaking later, but for a quick feature, you can place it and adjust later. (4:00)

I can control exactly how many wraps of the wire I get around the quilt using the circumference formula pi*D.  Recall the .804 diameter reference dimension.  Therefore, pi * .804 * 6 equals 6 full wraps.  You can use any formula here.  Wrap is very accurate about transferring properly.    I know the ends will be right on top of each other and they will be aligned with on of the vertical planes.  (4:50)

You can see how this operation can make some very specific pitch variation for springs.

Next is a simple sweep using the wire diameter determined in Extrude 1.  (5:45)  Here I make sure the wire does not intersect itself.  I then tweak the wrap sketch to get a good closed end.  (6:00-7:00)

Next, I trim the spring using the original quilt to determine the centers of the top and bottom wire ends.  This is the "ground" requirement of the part.  Notice how the part is now too thin at the ends.  (@ 8:30 was an error in defining the extrude cut) The wrap section is again tweaked to make the ends a little more substantial.  10:30)

Much of this can be automated by using relations.  You can even make this more universal with control of the straight and round in the wrap sketch.  In general, this is an -on the fly- version of a spring.  If you work with these a lot, and others also need to create them, it might be good to invest the time to make a universal version that can be set in the relation or added to family tables.  It takes a bit of extra effort to ensure success as a universal model.

## Re: Closed and Ground Spring - Alternative to Helical Sweep

One last question how do I hide this extruded feature that was used for construction?  I tried hiding it but everytime I save a open it agian it shows up.

Thank you so much! This helped me understand this so much better.

## Re: Closed and Ground Spring - Alternative to Helical Sweep

My pleasure, Kaci.  In order to keep things hidden, you go to the layer tree and use the right mouse button in the tree area, and select "Save Status".

If you have forgotten to save the layer status, you will get a notification whenever you save the part.

You need to have more than one line in the message area to see it.  You can do this by adding this to config.pro to make it default to 3 lines (or more):

visible_message_lines 3

...but you can also drag it manually.  I set mine as a default since good information gets hidden easily.

## Re: Closed and Ground Spring - Alternative to Helical Sweep

Oh, and on drawings, you can manage layer view specific.

View dependent layer settings are saved in the same way.

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