Question for Rhino users

[goodduck]

When loft. It will ask how many control points you want to rebuild with. Default is 10 and I always set to 1. It also ask how many inches you want to refit within. Default is 0.01" and I never need to play with that. Try set you control points to 1 if you have not try that yet.

[Gil]

Hi Murph,

Go to: File > Properties > Units. The menu contains tolerances for the selected unit value.

I always do a surface model without regard to the ability to unroll it first. This yields an accurate "envelope" from which you can "what if" developable sections to see how well the lofted sections will look on the finished model [pure synthesis before build].

+Gil

[Zathros]

Originally Posted by Gil

Hi Murph,

Go to: File > Properties > Units. The menu contains tolerances for the selected unit value.

I always do a surface model without regard to the ability to unroll it first. This yields an accurate "envelope" from which you can "what if" developable sections to see how well the lofted sections will look on the finished model [pure synthesis before build].

+Gil

I think he's trying to bang out models. The sample I gave him can yield a canopy of virtually any shape, bearing in mind that if you start with the premise that you are working with paper. Running the "Rails with the lines juxtaposed to the original drawing will yield a part similar to what you are attempting to interpret.

When producing anything, the first consideration must be the limitations of the material you are working with.

Pretty pictures a model does not make. Compound curves Paper will not take.

In Rhino, the methods aforementioned in this thread, add far more steps than necessary. I would guarantee you after all that work, the end result will be a part that you could making by "Running the Rails", that is, if you can envision the 'Rails". That is how Rhino works, otherwise, you have to rely on the "Smash" option. To unroll a surface in Rhino, you can "Loft, Trim, Drape, do what ever you wish, but the end result will be that the part will have been able to make by running "Rails'. You can always trim a part after you have unfolded it, if you have trouble seeing in 3 dimensionally.

[murphyaa]

Here's an example of what I'm doing. Look at the very front of the cabin. I haven't tried to unroll it yet, but I'm expecting all kinds of troubles with it. And for some reason, my version of Rhino won't let me set the control points to anything less than 10 when lofting.

[looker]

Originally Posted by murphyaa

I loft between curves. I try to avoid sweeping rails because that generates double curved objects that have to be butchered to be unrolled or smashed.

It will generate a developable (unfoldable) surface if you use 2 rails and sweep them with a straight line.

[Zathros]

Make sure your Profile curve is a straight line, and you will never have that problem. That model should be a breeze to make. It took me about 15 minutes to bang this shape that I have attached out. (not the A90, those were a Pain the the A_ _ !). The same applies to everything though. It is generic in it's shapes. All done with a straight line as the profile curve. Everything unrolled fine. Everything on the nose of the A90 unrolled the same way. (Please over look the tape marks).

[murphyaa]

Which is better; lofting, or sweeping rails?

[Gil]

Originally Posted by murphyaa

Which is better; lofting, or sweeping rails?

Depends. A line (or lines) swept through two curves will always unroll assuming that they're set up properly for Rhino to sweep them. The loft command is a lot more powerful than many might suspect and it's well worth a little quality time messing around with it to get a handle on it's capabilities. Straight line lofts should not be a problem. Just change one of the seem positions prior to lofting and see what happens...,

As usual it depends on what you're trying to do. Paper does not stretch and paper models are for the most part made of collection of straight lines wrapped around a set of sectionals trying their best to imitate compound curved surfaces. Some of the European modelers have resorted to removing layers of the paper at the section joints in order to obtain a smooth transition from one to the next. It's kind of anal but it does look good.

[Zathros]

Originally Posted by Gil

Depends. A line (or lines) swept through two curves will always unroll assuming that they're set up properly for Rhino to sweep them. The loft command is a lot more powerful than many might suspect and it's well worth a little quality time messing around with it to get a handle on it's capabilities. Straight line lofts should not be a problem. Just change one of the seem positions prior to lofting and see what happens...,

As usual it depends on what you're trying to do. Paper does not stretch and paper models are for the most part made of collection of straight lines wrapped around a set of sectionals trying their best to imitate compound curved surfaces. Some of the European modelers have resorted to removing layers of the paper at the section joints in order to obtain a smooth transition from one to the next. It's kind of anal but it does look good.

Especially true if you are going to paint a model, rather than relying on the printed graphics. You can then wet paper, and use "spoons", or other compounded surfaces to get the shape you are looking for. I sometimes the printer aspect is great, but also a curse. Before the advent of printers, you justmade a model out of whatever you wanted to use, paper, cardboard, a little plaster, metal armature, and,"Presto magico", you had your model. Now, there are "paper purists and all kinds of other "self imposed rules. Anyway, I stop, going off topic................

I imagine making shapes to determine if the shape is right at certain points is another reason why lofting is so important, and why Rhino is so powerful. As you can split a complex shape, duplicate the edge, and make a "test gauge", the options become unlimited.

[goodduck]

If nothing work for you send me that one piece you need to roll and see if I can do it for you.