I must be doing something fundamentally wrong. On the attached model, no matter what I do, I cannot make the very small extrusions, (holes), penetrate all the way through the side plates. Frustratingly, I managed to achieve it one plate, but cannot remember how I went about it!
In addition, where I have placed the text, the rectangular shape with a rounded end should be a recess, but no matter what I try, it just won’t happen. Boolean difference and make a hole are what I have tried.
Have I gone about modelling the whole thing incorrectly. HULL - Copy (2).3dm (10.1 MB)
BooleanDifference seems to work after selecting the big surface and then selecting the round surface to make the hole with…
For the closed-U shape on the right, you can try the trim command.
for trim, select the closed u shape first, then select the inner part of closed u shape of the large surface which you want to trim away.
or if you join the closed u shape fist into polysurface using join, then do booleandifferece as the other ones may work? not in front of pc now so haven’t tried it tho.
Ian, the U shape thing is doubled up - there is a closed extrusion there, which is the thing you want, but also the same shape as a bunch of unjoined, separate surfaces - delete those. Now, BooleanDifference the closed extrusion from the larger object.
If you are going to be using Rhino for solids operations like Booleans, please have a look at these:
that is what I ended up doing, but only by accident/trial and error. It seems to be a recurring problem that I find I am experiencing. Unfortunately, a lot of my “shapes” consist of several components. Is it advisable to always join these into one unit?
It depends a bit on what your end result needs to be. A few things to consider: If you are modelling for production, you will typically make a single unit of something that will be produced as one single unit. 3D printing will require closed (poly-)surfaces. The ClippingPlane feature in Rhino will only produce a capped section when the object that is clipped is a closed object.
The intention is to have some 3D printing done. I was intending to model what I want as best I can, and then have a professional check and/or edit as necessary to enable the printing. From what I understand, even the orientation of the model can effect the quality of the printed product. Additionally, 3D printing companies seem to base their pricing on volume of material, so some of my bulkier items need to be hollow, but to have sufficient wall thickness to be able to print, and to remain reasonably strong when printed.
I am checking that everything I model is completely closed, as I go, and hoping that I don’t get too much wrong, so that it will cost me an arm and a leg to have it fixed!
Hi Ian,
To remedy this situation where you have the boolean failing and want to trim up the hole extrusions;
Run split, picking the polysurface first, then split with the holes, then to remove the split segments - select previous, which gets you the polysurface and the split segemnts, then de-select the poly and delete what’s left, ie the segments. The result can then be joined up.
On the other shape, as Pascal said, there is a double up and a quick check for that is to orbit the model til you can do a clean widow select of the U-shaped part only - it tells you on the command line that there are 5 surfaces and 1 extrusion - that’s 5 surfaces too many, so while you have it selected, de-select the part you think you want to keep and delete the rest. You can undo if you’ve selected the wrong part and pick again because, in this case, the part remains selected due to the double ups so you don’t know that you have de-selected the correct part.
Split is the best way to do most of what you are trying… Make the shapes you wish to cut, extrude those shapes so they go through the object. The click on “Split’, select the object to be split then check on the extrusion as the cutting tool, click enter, (or right mouse click), then delete the extrusion. Remember to chose under display what curves you wish or do not wish to see. Don’t use “Split” to make Hull details, get familiar with the 'Project” command. Remember in project, to do everything in the same Viewport. You could project those names onto the side of the hull, and group them together with it, and they will unfold with it, if you are making a model.
Many thanks John; split worked for me. I’m just getting used to the “project” command. “Display” is also a new one to me, so I’ll familiarize myself with that as well.
That did it. Thank you.
