Unable to thicken surface models containing blends

[thecadman3]

Hi,

Unable to thicken surface models containing blends.

Please forgive the long explanation of my problem but it’s the only way I can describe it..

I have been using GSD to create some 3D models that will be used to create plastic panels for a scooter. I am fairly proficient at using GSD workbench for body in white and mechanical parts, but on the side I have starting to dable with Class A surfacing. I appreciate GSD is not really the tool to use (don’t have access to Icem, freestyle WB or anything like that) but I have managed to produce some models with complete curvature continuity.

I am struggling to thicken some of the parts/surfaces. Mainly on small edges where I have created blends. I have been creating small gaps between the 2 mating surfaces and then using blend to get my smooth edges. As you can appreciate this is really difficult/time consuming, but my main trouble is when trying to thicken! – it won’t. Tried all workaround like using bigger blends, closing/shelling, smaller thicken sizes and thickening in both directions.

The only way round this is to use fillet command (with conic option). I would like to use this for the small edges on my parts but do not want to compromise on the quality (as radius/conic will not produce curvature continuity).

For small edge radiuses would you really notice any difference between a small (3mm) blended edge and a conic fillet?

Thanks

 

[TibiX]

Hi thecadman3,

I have had problems such as the one you described (not being able to apply thickness to a surface) and what I did was to join surfaces as a I felt, and trying to thicken them. It is a recursive approach but it can work pretty well if you "guess" where the problematic areas are.

Hope this kind of approach will help you.

Best of luck!

 

[thecadman3]

Yes helps thanks

Do you mean do this only to highlight the problimatic areas? or create a multi thickened part from multi joined surfaces?

 

[TibiX]

It helps isolate the problematic area...
Not very professional, but it should work. This method is tried and tested by me

 

[thecadman3]

Definitly going to try this option....

Does anybody know if a small radius (with conic option set to 0.5) would be noticably different than using a curvature continuity blend? on the actual phyisical part.

 

[Azrael]

Have you done a surfacic analysis of the surface? checked minimum radius?

 

[thecadman3]

I have only looked at surfacic analysis to check any inflections so never used the radius analysis! the min is 1.15 on a blend. Im trying to thicken to 3mm.. could this be part of the problem? need to understand this

 

[flangewiper]

As you spotted, if your part thickness is 3mm then your minimum rads need to be at least 3mm otherwise it won't offset.

I get this lots with automotive bumpers where the Styled surface rads are less that the material thickness. In this case there's no option but to model the A and B surfaces seperately in GSD, and then create a closed surace in GSD and then finally a Solid in Part Design. This is what I do on 99% of the mouldings I do. It's far more time consuming that modelling one side in GSD and then using a thick surface but it's flexible and I can vary the internal and external radii to suit my requirements.

The A surface rads are usually fixed by Styling and are conic generated in ICEM or ALIAS but for the B surface I'll just stick a plain radius in that gives me the material thickness that I need and the fact that it isn't curvature matched doesn't matter as it's not seen. For A surface rads less than 3mm, you'd be hard pressed to tell the difference between a conic and a true rad but I normally use a 0.6 conic for rads between 1.3 and 3mm, and use a plan rad for anything less than 1.5mm.

 

[thecadman3]

Thanks for that..

I am doing just that for one of my parts. Although its a B surface it may be used to cut male Bucks for Carbon fibre parts.

I looked into the conic rad on youtube, and between them and a small blend, the differance is small. By adjusting the paramater (like you said 0.6) you can almost get curvature contiunuoity.