9 Replies Latest reply on Jan 7, 2018 9:27 AM by Andrew Kernan

Change direction that two parts of a sketch are pushed apart

Andrew Kernan Dec 21, 2017 8:33 AM

I'm creating a parametric drawing of a cylinder and I've run into some issues with how the case inserts are dimensioned. The screenshot below shows the how the cylinder looks in its default format.

But when I increase the cylinder length it pushes the head insert upwards, instead of the case insert downwards.

How do I set the cylinder length dimension so it pushes the case insert downwards, whilst leaving the head insert fixed at the radius? Its worth noting that the number of fins increases with cylinder length which is why there are more fins in the second screenshot.

Re: Change direction that two parts of a sketch are pushed apart

Deepak Gupta Dec 22, 2017 8:28 AM (in response to Andrew Kernan)

Add a relation between upper sketch entities and origin such that head insert position is fixed and then any changes in the value should push the case insert downwards.
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- Re: Change direction that two parts of a sketch are pushed apart
  
  Andrew Kernan Dec 22, 2017 11:16 AM (in response to Deepak Gupta)
  
  If I select the top entities of the sketch to be fixed or colinear, e.t.c... then my sketch becomes overdefined and if I change the cylinder height the insert stays where it is supposed to but the radius remains fixed even when it should be increased.
  
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  - Re: Change direction that two parts of a sketch are pushed apart
    
    Deepak Gupta Dec 22, 2017 11:25 AM (in response to Andrew Kernan)
    
    Will have to check the file (if possible to share) else check which other relation can be removed.
    
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    - Re: Change direction that two parts of a sketch are pushed apart
      
      Andrew Kernan Dec 22, 2017 12:13 PM (in response to Deepak Gupta)
      
      Ok, I'll attach the file so you can have a play around with it.
      
      Cylinder.SLDPRT.zip 866.2 KB
      
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      - Re: Change direction that two parts of a sketch are pushed apart
        
        Deepak Gupta Dec 22, 2017 12:34 PM (in response to Andrew Kernan)
        
        Your model is not correct. Cylinder length, case insert length, etc. are controlling the fin number which is not correct as top features should be driving the lower features and not other way round. I have made some changes in the model but you may have to work with number of fins equation and probably the gap between them.
        
        Cylinder-Updated.SLDPRT.zip 169.6 KB
        
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        Re: Change direction that two parts of a sketch are pushed apart
        
        Dustin Perreault Dec 22, 2017 1:00 PM (in response to Deepak Gupta)
        
        I am in agreement with Deepak. When modeling with dimensions that are driven by equations, you have to really plan out your modeling and even then I have found that you need to be creative with how you dimension in order to stop them from flipping or doing other strange things. Limit the features freedom to move anywhere but where you want them to go.
        
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        Re: Change direction that two parts of a sketch are pushed apart
        
        Andrew Kernan Dec 23, 2017 7:00 AM (in response to Deepak Gupta)
        
        Thank you very much for the help, the fin number equation definitely needs some tweaking. Just so I'm completely clear what changes did you make to the model?
        
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        Re: Change direction that two parts of a sketch are pushed apart
        
        Deepak Gupta Dec 24, 2017 1:11 AM (in response to Andrew Kernan)
        
        I've moved the case insert feature before the fin pattern. The file is attache din above post if you want to look at
        
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        Re: Change direction that two parts of a sketch are pushed apart
        
        Andrew Kernan Jan 7, 2018 9:27 AM (in response to Deepak Gupta)
        
        Just thought I would update you that I got the cylinder working properly, I was able to change around a couple of dimensions and I used an if statement to get the fin number correct.
        
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