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Patriot_1776
Patriot_177622-Sapphire II
22-Sapphire II
February 7, 2020
Question

Ok, this has to be a bug in the Spinal Bend command...

  • February 7, 2020
  • 2 replies
  • 2554 views

I've used one of my fave features, the Spinal Bend, many times over the years.  I prefer using them on quilts because then it's easier to have multiple Spinal Bends in a model.  THIS time I ran into a VERY weird problem.  The spinal bend failed on the surface, but yet worked fine with the solid.  What the?????

Any ideas?

PTC guys, what do you think?

2 replies

Patriot_1776
Patriot_177622-Sapphire IIAuthor
22-Sapphire II
February 10, 2020

What, no takers?  Anyone else think this is weird?

tbraxton
tbraxton22-Sapphire II
22-Sapphire II
February 11, 2020

I can not offer explanation of why the geometry kernel handles this but it appears to resolve your problem. I suspect it is related to the circles being split in half. My first attempt to mitigate the half circles did not work but using the below looks to work.

 

Convert your side layout curve to a a spline within the sketch and it works in Creo 4 M060.

Patriot_1776
Patriot_177622-Sapphire IIAuthor
22-Sapphire II
February 12, 2020

Boy, that's weird.  I actually never knew about the "Convert To Spline" command in sketcher.  I have never had any formal training in Creo 3 (or since the Creo Parametric/Pro 5.0 actually - I went from that straight to Creo 3), so this was one updated command I missed, thanks for pointing out a new command!

 

That is a problem that the spinal bend doesn't work as it should though, I'd certainly call it a bug.  The downside is that converting the sketch elements to a spline appears to actually change the geometry when it makes it a spline.  If you do a curvature analysis on it before and after converting it to a spline, you can see that when it's separate elements the lines are straight and the arc is a constant radius.  When you convert it to a spline, the ends of the lines change (actually become a reverse curvature compared to the "arc-ish segment") and the curve is not exactly a curve anymore.  Also I notice that when converting it to a spline all my "datums on the fly" failed because I used the line element as a reference.  The downside is that you can no longer reference any if the underlying geometry (like the line elements or the ends of the arc) but are limited to ONLY the ends of the spline, but considering the conversion actually changes the geometry I see why.  I can see that causing big issues, but not so much in this case.  AutoCAD had that command and I'd wanted Pro/E to have it for many years, so it's good they finally have it, even if it's not perfect.  It's good to know the command is there, but because of the change in geometry issue I probably won't use it much if at all.  Interesting though.

 

Thanks again!

tbraxton
tbraxton22-Sapphire II
22-Sapphire II
February 12, 2020

Convert to spline has been around for a long time, I am pretty sure it pre dates Wildfire. I used this extensively prior to the integration of ISDX into Pro/E. I think in the old menu driven menu it was labeled differently but it was there.

 

Conversion to a spline makes a new curve dependent on the underlying sketch entities. It is by design curvature continuous so your observations are accurate about curvature plots deviating from your reference curves. In a crude sense you can consider it the electronic version of a flexible curve tool used on the drafting table.

 

I know that within sketcher you can access the underlying geometry (lines & arc for your sketch) using query select. I am not sure about outside of sketcher but you should be able to embed geometry dtm points within the sketch to support on the fly refs linked to the underlying sketch entities.

 

You should submit the model to PTC support as I think it is a bug as well.

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