archturn Posted April 17, 2012 Share Posted April 17, 2012 I'm having trouble creating the helix need to use as a subtract from my stair baluster. The profile I am trying to "spin" always has the wrong orientation to the helix. Any help would be appreciated. drawing is attached. Quote Link to comment
archturn Posted April 18, 2012 Author Share Posted April 18, 2012 probably should have put this is solids modeling Quote Link to comment
michaelk Posted April 18, 2012 Share Posted April 18, 2012 (edited) This is a very interesting problem. Just to see if I understand, is the attached picture more or less what you are trying to draw? mk Edited April 18, 2012 by michaelk Quote Link to comment
archturn Posted April 18, 2012 Author Share Posted April 18, 2012 That is precisely what I am trying to do. How did you do it please? Quote Link to comment
michaelk Posted April 18, 2012 Share Posted April 18, 2012 I'm pretty sure I did it the wrong way. Something is happening with the nurbs curve underlying the helix that I don't understand. I'm hoping that someone will step forward with an explanation. When used as a path for an EAP it sometimes does a repeating pattern of one big turn and two small turns. If the profile is small enough, it behaves as you would expect... But extracting the curve back from one of those EAPs yields a nurbs curve with the same issues.... So I gave up with the helix and used a sweep. I'll post the file so you can see how I did it. It's not perfect. There is a slight seam. That may be because I was sloppy making the profile, but I suspect that it's a limitation of the method I used. I'm hopeful that someone with a better understanding of nurbs curves will offer a better solution. mk Quote Link to comment
archturn Posted April 18, 2012 Author Share Posted April 18, 2012 Thanks for your help. I'm with you until step 6 - extract all surfaces stitch and trim. Not sure what you did there Quote Link to comment
michaelk Posted April 19, 2012 Share Posted April 19, 2012 Sorry! 3D Tool set. - Extract Tool > Surface Mode > Prefs > Selected All Entities selected. Select the sweep and hit the green checkmark. That gives you a group of 55 surfaces. Ungroup. With all the surfaces selected Model > 3D Power Pack > Stitch and Trim Surfaces This gives you 2 generic solids. One is the one you want. The other looks like the original profile. Throw that one away. This whole step is because I wasn't able to subtract solid or split the sweep object. It's a "cheat" that turns the sweep into just a surface and then creates a solid out of those surfaces. Let me know if that doesn't make sense. mk Quote Link to comment
archturn Posted April 19, 2012 Author Share Posted April 19, 2012 I don't know if it makes sense or not. I'm a little in no man's land. I'm so accustomed to sweeps to get what I want because they are never tapered like this one. I've never used the 3D toolset like this so I'm not sure what I am doing. I guess it is like an intersect command? I get an error message: "surfaces could not be trimmed as they do not intersect to create a closed volume" Quote Link to comment
michaelk Posted April 19, 2012 Share Posted April 19, 2012 What did you use as the starting object for the helix-spiral? mk Quote Link to comment
bcd Posted April 19, 2012 Share Posted April 19, 2012 The primary issue is that it's laying in the xy plane. Select All Rotate 3d 90? about x to bring into standing In Front View Select the Spiral & the Profile Extrude along path selecting the options to Lock Profile Plane (relative to xy) and Fix profile (relative to the path normal) Select both the EAP and the main geometry Subtract you also need to tidy the profile a little as it doesn't marry exactly [img:left]http://techboard.vectorworks.net/ubbthreads.php?ubb=download&Number=7002&filename=Liquorice.png[/img] Quote Link to comment
archturn Posted April 19, 2012 Author Share Posted April 19, 2012 mikaelk When I tried to used the helix spiral I used a vertical line. When I tried to replicate what you did I did not use the helix spiral but the sweep. Quote Link to comment
michaelk Posted April 19, 2012 Share Posted April 19, 2012 Brian Nice catch. I never noticed that the lock was only xy instead of relative to the current view.... I'd still like to know what's going on with that nurbs curve. If you try to EAP an interior profile you can sometimes get the one big loop, two small loop pattern. Archturn, if you're still trying to do my very convoluted process, you may have created the extract with the wrong preferences and mode settings. (That would get the error you experienced.) Make sure when you extract you are in the Extract Sufraces Mode (4th mode) and the Extract Preferences are set with only Select All Entities checked. Post back or send a PM if you get stuck. mk Quote Link to comment
archturn Posted April 20, 2012 Author Share Posted April 20, 2012 BCD I did rotate as you suggested - Makes sense but I am still having issues with the EAP. As Michaelk has said you get strange results. I get 1 large loop, 1 small, 1 large, 2 small then 3 large. The EAP command is possessed. Quote Link to comment
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