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Rectangular helical sweep feature

Re: Rectangular helical sweep feature

BH OOI‌ Thanks for your idea and a your way to get a solution with normal available on board Tools. Whether it is the right solution, it is a interesting point of view.

Antonius Dirriwachter‌ Your comments about the idea from BH OOI‌ are also very needful. And your are absolutely right with the your comment about the orientation from the sweep. It has to be normal to the trajectory. And you are talking about to manage the following twist.

Either my English is so bad or google translate. That's why I have still not understand the following question:

  • How do you get the twist from the curve or the sweep straightened?

Thanks in advance.

Re: Rectangular helical sweep feature

You just make a "parallel" curve to your origin curve.

In you sweep sketch, you can use this Chain reference to orient your sketch.

The attached file won't fail without the additional chain, but you get the idea by interrogating the sweep feature.

Re: Rectangular helical sweep feature

This would be my entry for this challenge.

It utilizes a wrap to manage the constant rise.

This is fairly simple to make parametric for a variety of shapes.

This method also does not require a "guide curve".

P.S. This is also Paul's solution above and with the clarification, I would suggest his answer is correct.

Re: Rectangular helical sweep feature

Paul Sobejko wrote:

Unfortunately, I did a quick test and the wrap method will produce a consistent sweep.

Honestly, I'm not surprised that a sweep based on patterning copy-geometry type of features fails inconsistently.  I attribute this to poor numerical-error handling deep in the software. ...snip

There is a bug in early Creo 2 that fails at the seams of the sweep.  It goes normal at the "edge" of the cylinder rather than continuing tangent to the next wrap.

I learned this on doing a single sweep feature spring where every coil had a glitch at this seam.

It has since been reported fixed, but this was a fairly dumb bug as far as bugs go.

The real take-away, however, is other things we learned about continuous curves.  For one, they cannot make sharp corners, and they are very sensitive to accuracy settings.

One way to manage the asymmetry of the part is to assign the size of the datum planes.

Re: Rectangular helical sweep feature

I like this solution a lot. It's very simple and robust. I could alter the shape of the extrusion section and the wrap works just fine.

However, there is one issue I found. It works fine on the straight extruded surface but not on the tapered surface, as shown below:

Capture.JPG

May be for tapered surface, we have to deal it differently. Thoughts ?

Re: Rectangular helical sweep feature

too true; the logic doesn't work for cones.

You should be able to develop the right shape, but it is not straight forward.

Are you remembering to use the coordinate axis in the sketch?

Important element in helping to place the wrap! 

Re: Rectangular helical sweep feature

Well, you can project that curve that was wrapped about the "cylinder", onto its conical version:

wrap_over_cone.png

Pictured above is a sweep made using the "normal to projection" section plane control option.

The distortion is easy to observe:

wrap_closeup.png

If I reduce the size of the square wire, then you can get the "normal to trajectory" option to work for the sweep:

wrap_closeup2.png

However - similar distortion exists, so I couldn't tell you which is a more realistic model.

Re: Rectangular helical sweep feature

Any solid material would have significant deformation in the corners.

The deformation in Creo changes as you change the center of the section in relation to the sweep path.

You would have to map all 4 corners of the profile to get something more accurate.

That can be stitched together with boundary blend.

Re: Rectangular helical sweep feature

No sheetmetal offerings yet?

Re: Rectangular helical sweep feature

I have the wrapped curves projected through "normal to surface"  onto the tapered surface  and results are pretty satisfactory.

Capture.JPG