Blend with tangency - simple solution? 2

[Phim]

Hello,

I've been using Wildfire 3 for about a year now (5 years of Solidworks before that) and I'm still regularly having problems creating the simplest of geometry, exactly as I intend it, without going through an elaborate sequence of steps.

I have attached a couple of parts to this post. One shows the geometry that I would like to create and the other shows the sketches that I would like to be able to use (and should be able to fully define!)this geometry, using some sort of blend.

As can be seen from the required shape geometry (front or right view), I would like a tangent transition from a straight sided box up to the edge of the larger sketched square.

A regular, smooth, parallel blend between these three sketches creates a tangent transition, but the lower two sketches don't create a straight sided box.

Should I create an extrude first for this box and then some other tool to create the curved part?

Do I need guide curves? How many? Where?

Do I need to work with surfaces and have to knit these together to make a solid part? I have no experience of surfaces whatsoever and this seems a bit elaborate for such a simple shape?

This is really a simplified example of a more complicated piece of geometry that I'm trying to build, so I'm not looking for an answer saying - you managed to build the geometry with an extrude and a pattern of cuts - why do you need to build it as a blend - as I definitely cant use extrudes and cuts to make my shape.

Many thanks in advance for any solution/guidance.

 

[kimocal]

A VSS will do what you want. I have wf4 but I've attached a screen shot of how to set it up. I used your existing sketch 2 and mofifed it to only use the arc and straight portion. DTM1 is 15 units from the top datum, the same distance as your extrusion.

A condition of a VSS (variable section vs constant section under options) is for the guide sketches to be tangent therefore also satisfying your requirement.

Let me know if you need more help.

Cheers!

 

[piewarmer]

Phim

See attached. There are a number of ways to do it, but here is simplest

Essentially, create 2 blends rather than 1 where:
1st blend is from sq1 to sq2
2nd blend from sq2 to sq3
on 2nd blend apply tangency

http://www.edgepd.co.uk

 

[Phim]

Thank you for your answers Kimocal and Piewarmer. I managed to create the shape using a variable section sweep. Unfortunately, the method using two blends did not work as required - see attached part with correct tangency shown as a sketch. This shows exactly the kind of problem I've been having getting my head round some of the pro/e features - I would assume that a tangent blend up to a parallel edge from a straight sided box would create a curved surface that from the front or right view (or intersection)is a perfect, mathematically accurate arc - instead pro/e creates an unusual spline profile.

Thanks again,
Phim

 

[kimocal]

Phim - To get better control of the surface shapes in a Boundary Blend, use the "CORRECT_TANGENCY" sketch as second direction curves. I took your TANGENTBLEND_CORRECT_TANGENCT.prt and patterned the CORRECT_TANGENT sketch again 4x around the axis (REF 001.bmp). Now the sketches are set-up and can be used in a Boundary Blend (002.bmp). with the sketches SKETCH 1, SKETCH 2 & SKETCH 3 as the first direction curves (003.bmp) with the patterned CORRECT_TANGENCY ones as the Second Direction curves (004.bmp). The resulting surfaces follow the sketches pretty well (005.bmp). One thing to make sure when using a Boundary blend to have the connectors be consistent or you may get twisted results (006.bmp & 006a.bmp). These are similar to the Connectors used in SW for a loft or boundary blend.

I usually only use VSS, Swept Blend or Boundary Blend as they can do a lot of the what the legacy functions do but with more options/control.

There's a lot of good info to look through on the MCAD forums,

http://www.mcadcentral.com/proe/forum/forum_topics.asp?FID=3.

Look through the Sharp Technologies & Design Group Wildfire Tutorials too,

http://www.sharptechdesign.com/Tutorials.htm.

Last but not least the Leo Greene videos, which are I think the best and a lot can be learned from them,

http://www.e-cognition.net/