Can I lower tolerance to 1mm and have network curves mis at crossover and work?

Hi, I am creating something where 1mm or so doesnt matter, yet find myself trying to marry together profile curves until they meet so as to use them for Loft or Network.

Is this necessary or can they miss each other by 1mm or 1.5mm ?

The final shape will be sanded down and refined by eye so it seems ludicrous to spend hours tailchasing for when I adjust one to match, it messes up the curvature graph and if I refine that, then another needs adjusting due to the new refined curve.

This whole thing in fact applies to the bigger picture. all of which I am working on is not critical and can vary 1 or 2mm.

Could I alter tolerance to 2mm and get this done a lot quicker, surfaces would join, things would be watertight etc…or would they…

Whats the approach to objects where old dimensions were not accurate to 0.01mm but .1mm at most and I dont need even that. 1mm is enough. ?

Steve

Hi

I think you should consider using t-splines for this project. I purchased a mesh model from http://colacola.se/expo_303.htm converted, simplified and repaired it with t-splines before converting it into poly-surfaces in Rhino. His meshes are really exceptional. It will take you far less time to figure out sub-d modeling than it will nurbs.

Hi Strato,

 When I read your post about the mess model, I thought that you were talking about a poorly modeled file that needed a lot of work to clean up. Then I looked at the address of Cola and know is work to be flawless and finally realized that you meant 'mesh model'. I'm not sure why you would want to go to the trouble of converting a mesh model such as this to NURBS via T-Splines because I think that would mess up the even more amazing material maps that come with the model. I've done some nice renders of that Spitfire model from Cola. I think he uses MODO so they might be Sub-D models. Looking closer at your screenshot, I think that might be Anders Hurricane model.

 Good that he is so generous with his most excellent work. Here is my render of his Spitfire.

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I visited Anders site and need to correct myself on the point that he did the Spitfire in C4D and is indeed a mesh. So concise. He is using MODO more now and his work made me consider having a try with MODO. Let us know how your efforts go on the T-Splines conversion to NURBS, I was intimidated to even try that!

Hi, not aware of t splines,so another learning area to add to my pile.
whats the basic advantage, tell me about t splines and why it benefits imprecise shapes, 1mm is enough etc.
I have dimensioned plans to place into rhino and draw up for each item.
I see T splines is a plugin and see mention of t splines as a company.

https://www.youtube.com/watch?v=WV62TqZ_x2g has hairycraft wing section :smile:
and mention of website for aircraft makers, rhino and t splines. good find to start with :slight_smile:
wish each day had 48hrs to do all the learning I enjoy.

Steve

The conversion went fine. A lot of the simple small parts I just modeled in Rhino. I completed this project years ago when I was struggling to learn nurbs. I really did it to practice how to do a conversion as well as how to improve my rendering with tex maps. He does a fantastic job of making them.

The benefit of t-splines is being able to quickly create water tight complex curvature continuous surfaces. The downsides are accuracy and dense surfaces after converting them into nurbs. For jewelers these are not issues, for me they are. It’s a matter of using the right tool for the job. It should provide enough accuracy for your project. Much more so than the mess you are currently making in Rhino. T-splines sub-d modeling can be difficult to wrap your mind around at first. You can become competent with t-splines in a few months. It’s going to take you years to learn Rhino to complete complex air craft surface models. I’m sure you’ll find t-splines fun and intuitive. Watch their tutorial videos on youtube the ones Sky did are really amazing and inspiring.

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Cheers,
I rang up Rhino when first deciding what CAD prog to get, explaining in great detail what data I had to work with, the accuracy required, the making of aircraft frames and the need to model metal twists and bends, as parts are, as we know, given angled bends to turn sheet metal into rigid structures. I was told Rhino was the tool, no mention was made of T splines. I set about reading through both manuals levels 1 and 2 yet a lot of what I am discovering is available since I dont recall reading about, As soon as I get this job which requires a 15 hr day done, I shall be at the learning desk.
In an ideal world I would have liked to have just been learning, then when enough knowledge under my belt, set at the first job, but instead I am having to work flat out on deadlines etc before that has happened.

It should provide enough accuracy for your project. Much more so than the mess you are currently making in Rhino

My mess if thats how bad it is is disappoiting to me as I work so hard, at PC not 7 hrs but 15 a day on Rhino, if I had had a chance of learning it more before starting the job then there would be less mess. The mess i make though has been used on output successfully, its not a bad mess by some standards. I would like to see how it compares to others learning rhino, what mess they manage. Some might say to themselves thatll do, I dont know that level of finishing, I want to be precise, though have to bear in mind I am told 1 or 2mm inaccuracy is ok and aim for that by client.

The Sky tutorials are going to be great. Finding that at my first google was sheer luck.

I wish I knew where chapter 1 page 1 existed on the things I need to learn. I have now levels 1 and 2 V5 stashed away.

I am not sure if they come with exercise and videos, I trust they do. I had to have printed off the V4 pdf.
I also had Rhino VisualTips Video 4.0
I need however to see tools and methods used on real life examples.
It is important when learning to follow a thought out and structured course, diving into videos on youtube with varying quality of recording and narrative is messy.

Sky I hope follows ideal teaching methods.
I would like to find out more about what McNeel have created following the correct teaching route approach.

Are you aware of where one would get such an approach, chapter 1 page 1… on T splines additional to Sky or he the best for this correct route into understanding T splines ?

Am I right in saying T splines is not native to Rhino but a plugin ? maybe thats why I am not aware of them and wasnt told about them from the outset.

Maybe McNeel havent a tutorial section on them if so ? I havent looked yet to see if they have.

Steve

The aircraft in mesh mode is a Hawker Tempest V.

[quote=“Steve1, post:8, topic:16279”]Am I right in saying T splines is not native to Rhino but a plugin ? maybe thats why I am not aware of them and wasnt told about them from the outset.
[/quote]
T-Splines was an independent plugin for Rhino by T-Splines Inc. It was later acquired by Autodesk. So now it’s “T-Splines for Rhino by Autodesk”

T-Splines work more like subdivision modelling. You can quickly create and interactively modify smooth geometry. Another plugin with the same approach is Clayoo. T-Splines give you smooth surfaces fast. If you need exact matches, T-Splines will become harder to work with. Which is basically the opposite of Rhino, where you can get exact surfaces from exact data fast, but if you want smoothness but don’t have/care about exact data, things will get complicated.

Hi,
the word ‘complicated’ is a bit offputting.
Told to try T splines for where input data is from 70 yr old plans with data normally to one decimal point in mm, output required 1mm tolerance,

if you want smoothness but don’t have/care about exact data, things will get complicated.

is that sort of task, but I dont want it to get complicated, advice was it would be easier to achieve that goal.

What if I take an object created with T Splines and introduce into my overall build of the aircraft which up till now was done without T splines, what sort of marriage might I get ?

Steve

Best to just download and evaluate the Tools.

Imagine T-Splines to be like manually fitting a curve, just not in 2d but as 3d surfaces. The fewer control points to the curve, the easier they are to modify and adapt. More CPs will require a lot more work. On the other hand it may be hard to find an exact match with only three or four CPs so more precision requires more CPs and that makes fitting more time consuming. Keeping a good amount of control points and good precision and good smoothness requires careful balance. That’s the “complicated” part in T-Splines. The part you quoted was meant for the typical Rhino workflow, not T-Splines.

T-Splines provides functions to match a given T-Splines object to other Rhino geometry. The precision of the result will depend on the file tolerance and the topology of the T-Spline to fit. Your wing should be pretty simple and good to work with. Just don’t expect that for any other possible task.

T-Splines look and feel like smooth Rhino solids, but they don’t mix with solids while they are interactive T-Splines. At the end they simply converts to static NURBS patches or Rhino solids. No different workflow required here but you loose all T-Splines functionality at that point.

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