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4381.71 In reply to 4381.70 
Hi Michael,

Yes I am starting to really understand your .001 tolerance based on the bounding box. I tried all sorts of ter variations. A point like some suggested, a line as others suggested. Even larger radii. I found, like you said originally, that I would spin my wheels based on the tolerance issue. So I drew a bounding box for the airfoil and worked with that. It went a lot better. All functions worked. I did still have to change the mesh angle from 10 to 1 degree so that it looked smooth on my laptop. But it didn't seem to slow it down any. I created new geometry that may help you or whoever is interested experiment. It is setup to easily apply real life fillets at the base. The blade would need the airfoil ground out as well. So the model is much like you would see in a forging. Prior to being machined. Given the issues we spoke of, this is about as far as I can go with it. But I'm happy with this representation. Its good enough for now. I really enjoyed working with MoI over Rhino, PowerShape, and Autodesk 123D. The forum support was fantastic as well. I have never been a fan of CAD, I am primarily a FEA guy. I have found CAD work to be absolutely no fun. That is until I discovered MoI. I really enjoy firing it up and using it. In fact the more I use it the more a feeling of dread comes over me when I go back to Rhino. MoI is so easy to use. I love the fact that there aren't a lot of different ways to do the same thing. One way for one thing is a great idea to me. The UI is hands down the best I have ever seen. Icons that you can read and know what they mean. I think if you implement the adaptive tolerancing in the future it will really make MoI stand out even more than it already does. I'm going to continue to learn MoI as it definitely seems worthwhile.

One thing I learned through this trial was that Rhino wasn't doing as good as I thought. While I could jack up the tolerance (1e-6 meters) so that I could generate the blade. It still would not make solids from those surfaces and it would not fillet anything. I never realized it was having a problem with the geometry because I was able to work with it. I would much rather have what MoI was doing. Point out the problem right away. Rather than make me think things are ok, when in fact they are not.

The process right now would be to use PROP_DESIGN to generate the blade geo (airfoil profile and rails), model it as much as possible in MoI, and take it to SolidWorks to finish it out and do FEA. I never mentioned this as it was a little off topic, but it may answer a lot of the why am I doing this questions. The geo you see is the ideal shape. Under load it will deform a lot. So I have to generate new rails and iterate to determine the manufactured shape. So you have to go through this process a lot. Therefore ease of use is imperative. There is a lot of iteration required to determine what the real manufactured shape needs to be in order to yield the required shape for aerodynamic performance. Not to mention having to resize everything so it can withstand the extreme stresses. So this is not a one time through CAD and your done deal. For any given model, you will go through this process many many times over.


Anthony Falzone