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AndrewBeekman9108
Posts: 11
Registered: ‎01-19-2011
Message 1 of 6 (697 Views)
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How to generate a guide rail to control twist

697 Views, 5 Replies
09-18-2012 12:00 PM

Hello,

I am trying to model a forged steel table base so I can create some tooling to reproduce it.  See the attached photo of the base.  I am able to sweep along my 3D projected sketch path but there is a twist at the center that I believe I need a guide rail to control.  I have tried to draw a rail but it fails.  I suspect I am not drawing my guide rail correctly as to create the slight twist.  Any suggestions? I was considering drawing a shallow helix along the 3d sweep path but not sure that this is the beswt direction to head next.  I have attached the .ipt with the sweep (without guide path being used).

Thanks!

AB

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JDMather
Posts: 26,186
Registered: ‎04-20-2006
Message 2 of 6 (688 Views)

Re: How to generate a guide rail to control twist

09-18-2012 12:42 PM in reply to: AndrewBeekman9108

I noticed your first sketch was not constrained or making use of symmetry about the origin.

You might want to start here http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

 

Then here and here for information on 3D sketches

http://home.pct.edu/~jmather/content/DSG322/Inventor%20Tutorials/Inventor%2011%20Tutorial%207.pdf

http://home.pct.edu/~jmather/content/DSG322/Inventor%20Tutorials/Inventor%202011%20Tutorial%2014.pdf

Please mark this response as "Accept as Solution" if it answers your question.
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Contributor
AndrewBeekman9108
Posts: 11
Registered: ‎01-19-2011
Message 3 of 6 (674 Views)

Re: How to generate a guide rail to control twist

09-18-2012 06:21 PM in reply to: AndrewBeekman9108

I read through the tips, they were really helpful, thank you.   I still am confused about the guide paths though.  Since my profile is rectangular the bank/ twist is critical and I need to generate a guide path. Any reccomendations here?

 

Thanks,

AB

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GlennChun
Posts: 115
Registered: ‎06-10-2004
Message 4 of 6 (654 Views)

Re: How to generate a guide rail to control twist

09-19-2012 12:05 AM in reply to: AndrewBeekman9108

Hi Andrew,

 

See attached IPT.  It's far from perfect, but it should give you some idea of how to control twist using a guide rail.

 

2rail_sweep_fig1.png

 

2rail_sweep_fig2.png

 

2rail_sweep_fig3.png

 

Hope that helps,

 

Glenn

ASM Development

Autodesk T-Splines Component Development
Contributor
AndrewBeekman9108
Posts: 11
Registered: ‎01-19-2011
Message 5 of 6 (629 Views)

Re: How to generate a guide rail to control twist

09-19-2012 09:16 AM in reply to: GlennChun
Hi Glenn, Thank you- that was very helpful. How did you create the path and guide rail? It looks like you used your construction lines on the 30, 40 &50cm planes to lay out a free-hand spline. I was trying to create these paths using an intersection curve and had no such luck getting them to be "tangent continuous". Thanks, Andy
Employee
GlennChun
Posts: 115
Registered: ‎06-10-2004
Message 6 of 6 (623 Views)

Re: How to generate a guide rail to control twist

09-19-2012 09:58 AM in reply to: AndrewBeekman9108

AndrewBeekman9108 wrote:
How did you create the path and guide rail?

Hi Andrew,

 

I'm glad to hear that it was helpful. In addition to the 30, 40, and 50cm planes, there's an important plane at 60 cm above the floor ("table bot plane" in the browser). Here's what I did:

 

1. Roughly create free-hand 3D splines for path and guide rail. Each spline starts at a profile point.

 

2. Create 2D sketch points on the four work planes (Create a set of points on the +X side and then mirror them to the -X side).

 

3. Include the 2D sketch points in the 3D sketches for path and guide rail (Use "Include Geometry" command).

 

4. Add coincident constraints between the included points and spline points.

 

5. Right-click on the start and end points of each spline and select "Activate Handle".
a. Add a parallel constraint between each handle and Z-Axis.
b. Add a dimension to the handle.

 

6. Right-click on the midpoint of each spline (Each midpoint is located at 60 cm above the floor) and select "Activate Handle".
a. Add a parallel constraint between each handle and X-Axis (I forgot to do that in the attached IPT).
b. Add a dimension to the handle.

 

There are many different (and better) ways to model the two rails. My method above is just one example.

 

Glenn
ASM Development

Autodesk T-Splines Component Development

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