Complex surface problem?

[rocksolid2]

Hi there all solidworkers

I have what I think is a complex surface problem. I have an assembly file that contains each of the bones in the human hand connected togather, as separate parts. With each part, that is each section of each finger, I am trying to create "shells" of each finger i.e. I am hollowing out the middle of each bone to leave a thick outer surface with a hollow innner!

I've looked at several ways of doing this:
1. Scale the part down and then subtract the smaller part from the original as in a mold assembly, but the samller version is not in proportion and is extremely difficult to get close to the original proportions of the bone.

2. Tried thickening the surface to anything greater than '0' and was unsuccessful.

3. Tried offsetting at various measurements but only a zero offset was possible, then tried offsetting from the offset - still unsuccessful.

4. Offset and then thicken - nope!

My goal is to have a 2-3mm thick "shell" of each bone. The scale of the bones could be increased - is currently 1:1 but I'm now thinking maybe increasing the original scale might be an advantage?

Am running out of ideas now and was wondering if anyone could help - can email the file of one or some of the bones if anyone wants to have a go?! Would appreciate any feedback.

Thanks for your time

 

[CorBlimeyLimey]

May be i'm missing something here but ... can you not use the Shell command in the Features toolbar?

Simply select the Shell icon & if you don't select a face it will give you a hollow part. If you have SW2004 you can also have various wall thicknesses.

from (the City of) Barrie, Ontario.

If everything is going well, you have obviously overlooked something

 

[TheTick]

Offseting a surface, whether it's for shell or for offset, is mathematically limited by the minimum radius of a surface at any given point. A simple example is a cylindrical surface. If the radius of the cylinder is 2.0mm, you can offset the cylinder up to 2.0mm toward the axis.

Some things you migh try...

1.) Offset surfaces one at a time, and knit them together. Make surface patches to fill in for surfaces that don't offset. With luck, you will have enough surfaces to knit together and cut out the inside.

2.) Manually create offset surfaces by offseting curves from the surface, and produce a "nearly offset" surface with lofts from those curves.

3.) Use a different tool. SW doen't really have the tools to tackle this sort of problem well, anyways. Perhaps Rhino would work. Unigraphics has a lot of tools to expedite approaches suggested in #1 & #2. Another possibility is some mold-making software, as many of those software packages have advanced algorithms to add offset and shrink.

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