Shelling issues

joe_clark779

I ham having issues Shelling out a part, I keep getting a message saying that a part with selections cannot be shelled, |I have refresshed the browser bit to no avail.




https://cad.onshape.com/documents/5731ec00e4b0fe93d6b502cf/w/78eff63e6a597a34a6829c6d/e/ebc6c85d74fe0bb96ea6180f

joe_clark779

Ah, Ive got iot working sort of, it will shell out with wall thicknesses less than 0.26mm, unfortunatly i need somthing more like 3mm

erwin_1

Had the same problem, probably you have a small spherical geometry somewhere in your design. Apparently the way shells (and thicken) works is that these don't allow shells thicker than the radius of the sphere. See my question and answer from Neil here.

NeilCooke

The sphere issue is a particular case - in general a shell may not work if there is self-intersecting geometry. You can find where the troublesome area is by splitting the part up into smaller segments (using the split tool) and shelling each part. When you find the issue (usually one tiny small area) you can adjust the geometry until it works - usually!

joe_clark779

Ah, ok, I think that makes sense,

So I should keep the shape as square as possible untill i have shelled it pout, then apply any ouside fillets?

NeilCooke

@joe_clark779 - 99% of the time the shell should just work so you can happily put all your external fillets on first. Just sometimes a small surface on the outside can cause issues. My trick of splitting the part up works a treat if you're trying to find the rogue geometry - draw a set of lines that cross the part, extrude those lines as surfaces that intersect the part, then split the part using those surfaces - you can then shell each new part individually to find the area that won't shell.