blend curves degree 3-1 span

[david]

Hello everyone,

I am learning Alias for about a year now, working in the yacht industry. I have to say, I just love it! (I have been an NX user for over 10 years)

My trainer is a great expert coming from the car industry but he is one of those users who don't trust the "temperamental" behaviour of the blend curves, what I can understand but he can't therefore teach me how to use them, yet I really would like to make myself an idea of wether it is worth working with blend curves or not. There are quite a few aspects that I really like with those, the fact of constraining them to a construction plane, just to quote one.

I have hence been through the (very) few tutorials available on the net on the subject, the most comprehensives being the ones of Kerry Kingston (thank you very much Kerry!).

Now, in one of those (Tips for Working Effectively with Blend Curves), she states that if you want G2 at one end G0 at the other end, you would theoriticaly only need a degree 3 curve but if you turn the blend curve to degree 3, you would get 2 spans. In most cases it is true, but somehow, I managed to get a blend curves degree 3-1 span on my model and I can not explain why.
I've been trying many different parameters and I can not reproduce it, or only by chance...
I really would like to understand and being able to reproduce it as it is really relevant in my current tasks.

Can someone help me out with that?

Thank you in advance for your contributions.

David

PS: I'm using Alias Surface 2014 SP2

[ravenzep]

Hi there,

I think you are a bit confused. Since you use NX for 10 years, I m sure you know what spans are and all that stuff.

Well, theoretically, just to correct what you have read, or whoever said such statement, you can have G3 continuity between degree 2 curves. Because this does not depend on geometry degree, it depends on shape. Think about that, and if you cannot uderstand, or think is impossible, i ll tell you why.

Regarding the blend curves, i never really use them, for 2 reasons. 1st they are heavy, second i dont get the full control as I like to have. 

Anyway, it s fine if you like them, it comes down to personal preference.

If I remember, blend curves editing and stuff, was 1 span geometry, I dont know where are you getting that extra span from. It shouldnt happen.

ANything you want to know about them, just PM me, or post here some more concrete examples.

I ll be glad to help, if i know how to .:)

I ve used NX a lot, and kicked the hell out of it at some stage (I prefer it a million times to catia), but there is nothing like working with the freedom that alias gives you.

Different animals

Good luck and happy modelling