Creating a zig zag pattern

[Dhegderx]

Hi Guys, 

I am trying to draw a certain geometry but failing every time.  Please anyone can guide me how to draw this attached geometry.  they are  metal bellows and need to be revolved in 3D.

[BDCollett]

Can you link your attempt?

It looks like for a start, you have an open sketch profile.

[Dhegderx]

Hi the 2D sketch was drawn by someone else and it works perfectly. I want to replicate the same with different ODs and IDs but not been able to do so.

[BDCollett]

Please attach the file here so we can help you.

[Dhegderx]

Here you go ...

[BDCollett]

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@Dhegderx wrote:

Here you go ...

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The reason this will not work is because there are multiple lines on top of each other, the sketch is an open profile and is completely unconstrained. 

You really only need to draw one section, revolve it and then pattern that.

Try and have your sketches fully constrained, they give you visual feedback by changing color.

When you go to select the profile, if it is closed then it will highlight.

If it won't, you need to look at your sketch and see what went wrong. Drag points, delete lines etc until you can work it out.

[JDMather]

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@Dhegderx wrote:

…they are  metal bellows and need to be revolved in 3D.

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Do you have picture of similar real world part?

Is the geometry really sharp points as shown in your image?

Is the sheet metal really not uniform thickness as shown in your image?

[johnsonshiue]

Hi! Another approach is to create a V-shape sketch. Revolve it as a surface. Then pattern it based on the span. Lastly stitch the surfaces into one quilt and thicken it as a solid body.

Many thanks!

[JDMather]

@Dhegderx 

Where did you go? 
I can show you a more efficient technique that is fully parametric, but first I wanted to be sure of your true Design Intent.

[Dhegderx]

Sorry for late response..

(This is a rotary mechanical seal unit) 

Design intent is purely for manufacturing purpose only... 3D model and 2D manufacturing drawing will be sent out for manufacturing. 

32MM is the overall free length and 28MM will be the compressed length. 

Thanks 

[BDCollett · Accepted solution]

I am going to assume you are not trying to have the actual seal manufactured, but need a representation for a design?

The bellows will look quite different to a the "ZigZag" you have drawn.

They would look more like this; the sketch is more complicated.

Do you need to have the part actually flex or just be static in an assembly?

[Dhegderx]

This is exactly how it looks... I wanted to draw it like you did but I never understood how its done.

1- The seal will be manufactured, till now our company just used to indicate metal bellows with zig zag pattern and the supplier would understand that its metal bellows.

2- I am not doing any assembly of this , so flexibility is not needed.

Can you make a short video of how its done , it would be very helpful for me for the future work. we deal with these seals a lot and If I represent it in the way you have done it will be more clear and understandable. 

[BDCollett]

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@Dhegderx wrote:

This is exactly how it looks... I wanted to draw it like you did but I never understood how its done.

1- The seal will be manufactured, till now our company just used to indicate metal bellows with zig zag pattern and the supplier would understand that its metal bellows.

2- I am not doing any assembly of this , so flexibility is not needed.

Can you make a short video of how its done , it would be very helpful for me for the future work. we deal with these seals a lot and If I represent it in the way you have done it will be more clear and understandable. 

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I see, so you only need a representation of the bellow.

The design is really just understanding basic sketch geometry. If you wanted to reuse the shape you can make a sketch block and then easily add it to other designs with the same bellow.

I do not have time right now to make a video, I will try to do so later on and share this file with you.

I did not completely finish this one, as the sketch contains a lot of curves it needs more work to constrain it while allowing parameter changes to update the shape correctly.

[Dhegderx]

Thank you so much for taking such an effort … Really appreciate your help

Cheers to all the mentors in the forum. 

[Dhegderx]

can you help me with this? ....

[BDCollett]

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@Dhegderx wrote:

can you help me with this? ....

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Sorry I didn't get time to go more in to detail with this. 

I have attached the file for you so you can take a look anyway. I hope it helps.