Inventor General Discussion

Inventor General Discussion

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Valued Contributor
AnthonyPaul2010
Posts: 55
Registered: ‎07-19-2010
Message 11 of 15 (86 Views)

Re: Contact sets keep breaking - how to fix?

03-28-2012 03:40 PM in reply to: RayFeiler

Yeah I've tried angles of just less than 180 and it works so I'm almost convinced it has something to do with the z direction of faces used for constraining.

 

When you place an angle constraint which method do you use of the three choices?

 

  1. Directed
  2. Undirected
  3. or the Explicit Vector Reference (which is the default selection).

 

I'm assuming because EVR is the default that this is the one you are supposed to use the most.

 

I'm thinking that if I learn the proper application of each of these three choices then maybe it might help me solve the problem.

 

What type of angle constraint do you use the most?

Anthony Paul (from Cairns, North Queensland, Australia)

Product Design Suite
Inventor Premium 2012 - SP1 Installed
HP 8760w I7-740M Laptop
Windows 7 Professional 64
12 Gb DDR SDRAM
AMD FirePro M5950 Graphics Card
Valued Mentor
RayFeiler
Posts: 402
Registered: ‎10-07-2008
Message 12 of 15 (78 Views)

Re: Contact sets keep breaking - how to fix?

03-29-2012 07:06 AM in reply to: AnthonyPaul2010

When I use angle constraints I always use directed. Maybe someone with more experience can help you with the other choices.

Directed.png

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harco
Posts: 879
Registered: ‎02-16-2006
Message 13 of 15 (69 Views)

Re: Contact sets keep breaking - how to fix?

03-29-2012 01:42 PM in reply to: AnthonyPaul2010

Yes use EVR it was introduced to overcome the flipping problem.

It positively tells Inventor which way is up so that positive and negative directions can be specified.

Generally apply the 2 selections of edges or faces for the required angle and then select another edge or face perpendicular to the plane of the first 2 selections.

 

On a side note I'm not seeing how you are slewing you assembly using the ram that's flipping, it looks like a lift ram to me.

If this is so then surely you are hitting overcentre at 180º and serious loading.

 

Can you simulate the problem with 4 very simple basic parts, an arm, a turntable, a rod and cylinder.

Sometimes it's a bit trial and error trying to get a set of constraints to perform the function you want, especially if there are multiple movements.

It can be the order in which Inventor solves the constraints too, I have seen things not work and delete an early constraint but put it back in later on and the assembly then works.

Try not to drive the ram itself but drive the pins it is attached to then the ram follows where the pins go.

Hope these suggestions help.

Contributor
feame
Posts: 11
Registered: ‎06-29-2011
Message 14 of 15 (59 Views)

Re: Contact sets keep breaking - how to fix?

03-29-2012 04:55 PM in reply to: harco

harco wrote:

Yes use EVR it was introduced to overcome the flipping problem.

It positively tells Inventor which way is up so that positive and negative directions can be specified.

Generally apply the 2 selections of edges or faces for the required angle and then select another edge or face perpendicular to the plane of the first 2 selections.

 



Still doesn't work. My cylinders and assemblies still flip inside out. I'm sure I'm not the only to find that.

 

Valued Contributor
AnthonyPaul2010
Posts: 55
Registered: ‎07-19-2010
Message 15 of 15 (57 Views)

Re: Contact sets keep breaking - how to fix?

03-29-2012 04:58 PM in reply to: feame

After spending nearly a week on this problem I am convinced there are other IV users having the same problem.

 

I am convinced that it is a bug in the software?

Anthony Paul (from Cairns, North Queensland, Australia)

Product Design Suite
Inventor Premium 2012 - SP1 Installed
HP 8760w I7-740M Laptop
Windows 7 Professional 64
12 Gb DDR SDRAM
AMD FirePro M5950 Graphics Card
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