Another Pro/E bug: Variable Section Sweep problem.

[DELETEME]

I have a 6-lobed part I'm trying to create like a helical roots blower set where I have a twist but also the part tapers at say one degree along it's length. The feature fails every time. If I try and simply put circles in all the points where radii would exist, it will regenerate, but as you can see SOME of the resultant tube twist the wrong way!!! Very frustrating. Variable section sweeps are difficult enough without the actual software failing to work correctly. Any thoughs? Thanks.
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[eric.mills]

Your picture did not come through on the forum. Sweeps have certain processes to get them to work. I find the best way to debug an issue like this is to change each section at a time until I find the section that makes it fail. Also make sure that all of your sections have the same amount of points; good example is going from a square section to a circle. You have to break the circle into four points in the sketch in order to match the square. Also try to match the same start points in each section along the traj. Otherwise you can get some odd twists in the protrusion. I hope this helps.

[DELETEME]

"Eric Mills" wrote:

Your picture did not come through on the forum. Sweeps have certain processes to get them to work. I find the best way to debug an issue like this is to change each section at a time until I find the section that makes it fail. Also make sure that all of your sections have the same amount of points; good example is going from a square section to a circle. You have to break the circle into four points in the sketch in order to match the square. Also try to match the same start points in each section along the traj. Otherwise you can get some odd twists in the protrusion. I hope this helps.

[eric.mills]

If you would like you could email that picture directly to me and I might be able to help on this further. Just click the email tab on the message section. Eric

[DavidButz]

CM I'm with Eric; wish I could see the picture. Two thoughts however: (1) if you are using a Variable Section Sweep, have you tried an equation using trajpar to control the taper? (2) a General Blend might be a better tool than a VSS. Somewhere in the PTC knowledge base is a wing section where the same airfoil section is retreived at least twice, with different scales, then twist imparted by specifying an angle around the z-axis. If you are unfamiliar with either of these options, we could provide more detail. David

[DELETEME]

"David Butz" wrote:

CM I'm with Eric; wish I could see the picture. Two thoughts however: (1) if you are using a Variable Section Sweep, have you tried an equation using trajpar to control the taper? (2) a General Blend might be a better tool than a VSS. Somewhere in the PTC knowledge base is a wing section where the same airfoil section is retreived at least twice, with different scales, then twist imparted by specifying an angle around the z-axis. If you are unfamiliar with either of these options, we could provide more detail. David

[eric.mills]

What's the price on the Pro/Workaround module that you paid? Second how about the pricing on the Pro/Fanity module? I'm sure could use those modules every once in a while. I wonder if there is a Pro/Preventcrash module? My last suggestion for you was to use smaller sections or just one lube and either pattern the others or make VSS of the other sets. Sometimes too much stuff for Pro-E to handle in one feature or too much for the human to debug. Its sounds like you have at least got to a goal.

[DELETEME]

"Eric Mills" wrote:

What's the price on the Pro/Workaround module that you paid? Second how about the pricing on the Pro/Fanity module? I'm sure could use those modules every once in a while. I wonder if there is a Pro/Preventcrash module? My last suggestion for you was to use smaller sections or just one lube and either pattern the others or make VSS of the other sets. Sometimes too much stuff for Pro-E to handle in one feature or too much for the human to debug. Its sounds like you have at least got to a goal.

[DELETEME]

Ok, here's something to be very aware of: The spine trajectory on a VSS produces it's own centerlines. Do NOT attempt to mirror geometry about these centerlines. Create new ones to mirror geometry about. Now, this did not solve my particular problem with the lobes unfortunately (though I will look at it some more), but when I created the section with all circles at the lobe and valley points as a test, they all twisted the correct direction now, so this is definately something of an improvement. I would imagine this problem would exist in sweeps and swept blends as well and could cause failures there too. If you have a problem where these features fail and you can't figure out why because it SHOULD work, this may be the problem. Beware. Of note, a PTC management employee contacted me for info and I sent him a couple files with a detailed explanation, so hopefully they'll work on fixing this.