@team222badbrad (team222badbrad) posted a new topic, subject "Inventor Tetra Connector". It read:

   Ok I have tried to draw the tetra connector in the 2005 kit of parts from the dimensions given on the FIRST website. I tried everything I know of to get the whole tetra game piece assembly made in Inventor, but I found this very hard to do. I also found the tetra connector very hard to make :eek:
    
    If anyone has a whole tetra assembly made from inventor or one that can be imported to Inventor that would be great!
    
    Sheet metal parts, angles, and Inventor are not my thing…

After which, @Curt_Henderson (Curt Henderson) added

    Your not alone!!
    
    I have about 3-4 hours trying to model the Clover coupler so I am able to assemble the center goal.
    
    I can model the connector but when trying to assembly the tetra the constraints bomb.
    
    I have tried checking the angle of the three faces and all seems OK (the same). I am not sure if it is an Inventor fold command variance or errors in my sketch that produces angle error when the connector gets folded to the 35.3d angle.

To which @rmmlg (rmmlg) replied

    How did you bend the part 33.5 degrees. I thought it might be best to make the triangle in the center and the outer clover parts and mate them together, but there's got to be an easier way.

To which @Curt_Henderson (Curt Henderson) replied

    There is a drawing showing how the geometry is arrainged and on it it says to bend to 35.3d at the start of the radius that is between the Clover Leaves.
    
    I have tried bending it with the bend line at start, middle and end without success.
    
    I'm not sure where to go from here. I'll pobobly wait and talk to the Inventor Guru where I work and see if he has any more success.

After which, @rmmlg (rmmlg) added

    But where is this bend command to which you are referring.

To which @Stu_Bloom (Stu Bloom) replied

    Curt Henderson:
    
    > Your not alone!!
    > 
    > I have about 3-4 hours trying to model the Clover coupler so I am able to assemble the center goal.
    > 
    > I can model the connector but when trying to assembly the tetra the constraints bomb.
    > 
    > I have tried checking the angle of the three faces and all seems OK (the same). I am not sure if it is an Inventor fold command variance or errors in my sketch that produces angle error when the connector gets folded to the 35.3d angle.
    
    I can't say that I have a solution (yet) but I am sure the 35.3 degree angle is rounded off. I'll be continuing to work on it … until I have a solution or someone beats me to it …

After which, @Curt_Henderson (Curt Henderson) added

    The Fold command is in the sheet metal environment.
    
    I start the part as a sheetmetal part, created the clover leaf pattern and then created a bend lind as mentioned on the print.
    
    When you use the Fold command you have options as to where the bend line will be oriented. I had the best success with having it at the start of the bend.
    
    Good Luck

To which @petek (petek) replied

    I've attached our TH Connector Inventor part. I had to move the End of Part marker in the browser to get the file size below 100K. When you open the file, drag the End of Part marker to the bottom of the browser and save the file.
    
    It took a little thought to lay out, but if you do it the way Inventor wants you to, it isn't all that hard - just a little time consuming. The way I made it I was able to fully constrain the tetrahedrons to the connector using Insert constraints for all but the very last mate, which I used a Mate of the hole centers for.
    
    To make the connector “clover” I followed this procedure:
    
    Use the Sheetmetal template and set the thickness to .098 (in Parameters).  
    Start by drawing the 2.55 and 1.25 layout circle constructions. I recommend using the Fix constraint to nail down the origin of these circles at the origin of the sketch axes.  
    Then draw construction lines at 30, 90 and 150 degrees, intersecting the origin.  
    Draw the top “petal” 1.95 circle at the intersection of the 2.55 circle and the vertical axis.  
    Next, draw a 0.093 circle at the intersection of the 30 degree line and the 1.25 circle. Repeat on the other side at the 150 degree line.  
    Draw a line tangent to the 1.95 petal and the 0.093 circle.  
    Repeat these steps for the other three petals.  
    Trim the “extra” from the 1.95 and 0.093 circles.  
    You should now have the outline of the part.  
    Draw the 0.375 hole circles.  
    Exit the sketch and save your work.  
    Use the Face feature to “extrude” the sheetmetal thickness. If this fails, go back in the sketch and make sure you can close the loop.  
    Create a new sketch on the face of the part and draw the fold line as shown in the PDF.  
    Exit the sketch and use the Fold feature tool to make your bend.  
    The 35.3 degree dimension on the PDF is rounded from the delta/2 (=arccos(1/3)/2) If you want your connector to mate to the tetrahedron ends, use 2206593309 (or enter the formula in Parameters, like I did) - otherwise you'll get constraint errors.
    
    By the way, check out Math Forum's Tetrahedron info for the formulas for this beast.  
      
    2005-Arena-TH Connector.zip (81.8 KB)  
      
      
    2005-Arena-TH Connector.zip (81.8 KB)

To which @team222badbrad (team222badbrad) replied

    Thanks!!!
    
    The file works great.
    
    I have included a picture of the tetra using your piece.  
      
    
    
    c79c8f7c25de64d52e61919fa72bf818b140dc69.jpeg1084×612 26.5 KB
    
      
      
      
    
    
    c79c8f7c25de64d52e61919fa72bf818b140dc69.jpeg1084×612 26.5 KB

@Lucid (Lucid) replied

    It seems that you are all bending it on one line. In reality the clovers have a smooth curve. Have you thought about drawing the curve as a surface inb AutoCAD and importing it? This might be more than you want though.
    
    Lucid

To which @team222badbrad (team222badbrad) replied

    Lucid:
    
    > It seems that you are all bending it on one line. In reality the clovers have a smooth curve. Have you thought about drawing the curve as a surface inb AutoCAD and importing it? This might be more than you want though.
    > 
    > Lucid
    
    It does not matter how they look, just as long as they allow Inventor to make constraints that do not crash!

@SteveC116 (SteveC116) replied

    I'm not sure what you're making these models for, perhaps the animation? Anyways, if they are supposed to look like the tetras that will be on the field, there will be end caps on the pipe that the connectors connect to (team222badbrad - you just connected the connector directly to a pipe)
    
    Also, I met with Dave Lavery just the other day to discuss what materials and coloring will be on the field, and he told me the pipes for the tetras will be aluminum with a matte finish, while the end pieces will be a similar shade metal, but more glossy.

So @team222badbrad (team222badbrad) replied

    Yes I know they need end caps, but I do not have dimensions for those… 
    
    If anyone has those would you please share?
    
    I am personally not modeling them for anything in particular. I may eventually build a whole field just for something to do.
    
    I just build the model shown in this thread to see if the tetra pieces part on here, actually allowed me to make constraints in Inventor.

@Jeff_Waegelin (Jeff Waegelin) replied

    Could anyone post a full model of a tetra? I'm not the best with inventor, but I want one that I can look at and spin around and such with.

Then @system (system) said

    Jeff Waegelin:
    
    > Could anyone post a full model of a tetra? I'm not the best with inventor, but I want one that I can look at and spin around and such with.
    
    If you do post a file can you also post a .STP (STEP) file so that I can import it into SolidWorks. :eek:

Then @FarooK (FarooK) said

    thanks a million guys, we have completed the side goals, but are still in a dead end when it comes to the centre goal, as we do not have any drawings of the centre couplet or the base couplet.
    
    I will put up a drawing of the goal if we get how to make it, hopefully by tomorrow  
    In the meantime, any help on how to make them will be greatly appreciated

Then @petek (petek) said

    Jeff Waegelin:
    
    > Could anyone post a full model of a tetra? I'm not the best with inventor, but I want one that I can look at and spin around and such with.
    
    We'll post it on our website as soon as we have it (the site) set up for it - probably in a couple of days. The assembly is way to large a file to post as an attachment - the connector alone just made it under the 100K limit.

After which, @ajlapp (Anthony Lapp - Owner/Operator 221 Robotic Systems) added

    please do post the completed tetra…better to share our resources than try to build one from scratch.

Then @Pat_McCarthy (Pat McCarthy) said

    I tried opening that one that was posted, but when it opened, I could not see the part. Mousing over the model parameters, I could see the outline, but how do i make it visable?
    
    I'm using Inventor 8 Pro

Then @team222badbrad (team222badbrad) said

    You have to open the file.
    
    Once it is open drag the little red circle with a white X named END OF PART to the last place on the list.
    
    This is located in the browser bar. If you do not see the red circle click view, then toolbars and then click on browser bar.
    
    I will try to post the tetra without the end caps…

To which @FarooK (FarooK) replied

    we are trying to create a centre goal to test our robot design, but we are having problems with the base couplet (flat surface) and the middle couplet (four attachments)  
    has anyone been able to create that? FIRST did not provide the design in their manual  
    help on making them would be greatly appreciated  
    CAD, Team 1241

Then @petek (petek) said

    Here's the link to our Inventor 30 in. Tetra (http://www.cybersonics.org/cybersonics/awardentries/2005/inventor2005/30inTetra.zip)

To which @ajlapp (Anthony Lapp - Owner/Operator 221 Robotic Systems) replied

    my version of inventor won't open the tetra file. any chance you can post a step file or anything else so i can use it unitl i get the newest stuff. thanks.

@petek (petek) replied

    ajlapp:
    
    > my version of inventor won't open the tetra file. any chance you can post a step file or anything else so i can use it unitl i get the newest stuff. thanks.
    
    I probably won't be able to post it until Friday, but I'll let you know when the STEP file is up.

@wayne_05 (wayne 05) replied

    Hey guy the ifirobotics web site has full cad models of the tetras the center goal in step
    
    http://www.ifirobotics.com/first-2005-field-parts.shtml


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