Set side of a tangent constraint

[robertmarteau]

Hi,

Trying to create a parametric design of a metal bender (the idea is to have fusion compute the height setting of the mobile roll for a particular bending radius), I faced an issue I can't quite solve. Not that it's really surprising, since I'm not very proficient with Fusion, but still...)

On this sketch, the big circle is the metal piece being bent (thickness : 40mm, diameter parameter set to 920mm) and the 3 smaller circles are the bender rolls.

The inner side of metal piece is set to be tangent to the upper roll, while the outer side is tangent to the 2 lower rolls. So far so good...

But if I set the bending radius to a smaller value (say 200mm, for a 400mm circle diameter), i get this:

Of course, the constraints are still respected, since the center (previously upper) roll is still tangent to the inner side of the metal piece, but it's now on the wrong side of it...

--> Question: how can I specify to Fusion that the tangent relationship should not "switch sides" ?

Thanks in advance for your help,

Stan

[g-andresen]

Hi,

Please share the file.

File > export > save as f3d on local drive  > attach it to the post.

günther

[jhackney1972]

You may have to drop back to using a little geometry instead of sketch constraints.  In the supplied model, there are two parameters.  Change them to see the sketch reaction. 

[robertmarteau]

@g-andresen: here's the file. Sorry, it's a bit of a mess since it's a file I use for various "miscelleanous" stuff. It's in sketch26...

@jhackney1972: what do you mean by "drop back to using a little geometry"?

[jhackney1972]

Open my attached file and change the parameters to see the tangents are maintained.  I am using geometry instead of sketch constraints.  Mainly change the large circle OD, or course within reason.

[TheCADWhisperer]

@robertmarteau 

Examine the Attached file.

Notice the color of the sketch entities (fully defined).

The reference dimensions shows how high to place the center roller.

[robertmarteau]

Thx! I'll look into it this tomorrow when I get back home!

[TheCADWhisperer]

@robertmarteau 

Blue lines and white dots should keep you awake at night.

If necessary - add intersection sketch points as demonstrated by @jhackney1972 

Take advantage of anchoring to the Origin.

Take advantage of symmetry about the Origin.