dpaulku Posted June 12, 2009 Share Posted June 12, 2009 I'm working on designing form work that will ultimately build a curved "flying" reinforced concrete stair case... architects, go figure. I have 2D planimetrics that I can relate to but my puzzle now is going to be developing bulkheads that will form the bottoms of the side walls of the stair case. The stair is two flights separated by a midway landing. I can effectively project the actual grade of the bottom of the walls which follow the back side of the steps. The steps will be placed after the walls are complete. The puzzle is in drawing the 18" bulkhead that not only rises with the steps but curves with the walls. As I see this problem, curvature of the bulkhead is not the same as that of the stairway since the bulkhead is not in the same plane as the floor. My problem is in how to establish this secondary curvature so that the mill can CNC the necessary shape to fit the gap created by the two sides of the form. Anyone have any experience with this? I'm thinking I might be able to establish 3D points along the slope as it rises and snap a 3D polyline to them, then somehow lay that down flat to capture the curve developed. I can "see" how it might work but just don't know if there are tools to do it this way. I've got no actual 3D modeling experience but may have to resort to that if it ultimately makes it easier. Thanks for your time. Quote Link to comment Share on other sites More sharing options...
SEANT Posted June 12, 2009 Share Posted June 12, 2009 Is the curved wall circular in plan? If so, perhaps one of the resources in this thread would be useful. http://www.cadtutor.net/forum/showthread.php?t=31757 Quote Link to comment Share on other sites More sharing options...
dpaulku Posted June 12, 2009 Author Share Posted June 12, 2009 Seant, the plan is not technically circular. The "architect" used a polyline to define the curvature. It is close to an arch but not quite. Your link is just about the ticket. I'll see if there's a way to make a "real design" fit the architect's. As a matter of practicality my application will not be as pronounced as the screw conveyor examples you've offered in your link. My best fit curve of the spline is something like 329' R. The amount of twisting that will develop as the grade rises might be negligible. All things I have to flesh out. Thanks for your comments! Quote Link to comment Share on other sites More sharing options...
scj Posted June 12, 2009 Share Posted June 12, 2009 Have a look at http://www.ant-ares.de the first video should meet your problem Jochen Quote Link to comment Share on other sites More sharing options...
dpaulku Posted June 13, 2009 Author Share Posted June 13, 2009 Have a look at dubya dubya dubya .ant-ares.de the first video should meet your problem Jochen Thanks SCJ, I did look at that via another thread. Nice vid, interesting application... too much German for me to babble-fish... Quote Link to comment Share on other sites More sharing options...
BIGAL Posted June 15, 2009 Share Posted June 15, 2009 You may want to experiment with using UCS and create a drawing plane at center of radius but at the incline angle did this for a spiral staircase hand rail. Important part is that I only did one tread then copied each tread vertically and rotated horizontally making a complete spiral. Need 3 points for the UCS centre and the two stair ends but must be in 3d with Z values. Quote Link to comment Share on other sites More sharing options...
dpaulku Posted June 15, 2009 Author Share Posted June 15, 2009 You may want to experiment with using UCS and create a drawing plane at center of radius but at the incline angle did this for a spiral staircase hand rail. Important part is that I only did one tread then copied each tread vertically and rotated horizontally making a complete spiral. Need 3 points for the UCS centre and the two stair ends but must be in 3d with Z values. BigAl, using the stair incline as a base surface is a great idea too. That may lend itself to my application. I only have to recreate a flat representation of the incline so things are a little easier in that regard. What I'll need to do is bone up on how to get an arch into a 3D attitiude. If I draw an arch at 0,0,0 will I be able to rotate one end upwards, using the other end as the center point? I don't see why not... The other method would be to somehow project a line onto a 3D cylindrical surface having the same radius a my stair curvature. This is what I originally envisioned after seeing the screw conveyor posts. BigAl, I see that you are using Civil 3D. If I only had access to a nice roading package again this would be done. All I'd have to do is build an alignment along the edge of the form at the grade of my stair and push an appropriate cross section up the the stairs. Right now my problem looks like a nail cause the only tool I have is a hammer... I do appreciate having this forum to bounce this problem off of. You've all been very helpful. Stay tuned! Thanks Quote Link to comment Share on other sites More sharing options...
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