Hello all! Thank you ahead of time for your time. I am having an issue figuring out what
is going on with my model. I need a closed polysurface so the part can be machined. However, even after using ShowEdges, BooleeanUnion, and Join, I am still having a few issues. I am still learning in rhino and could use all the advice you are willing to give.
Thanks Again.
Earring mold CNC.3dm (3.4 MB)
Select the objects. Then in the menus, click on Analyze > Show Edges. You have several naked edges. They will show up in pink. I usually solve these types of problems one by one. They can be very annoying. Looks like some bad boolean operations. As you gain experience, you will have fewer of these problems as you will make better cutter objects (try to avoid coincident faces/edges whenever possible).
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see this video-
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you are suffering from āthe tolerance donut holeā
what is happening is you have intersections that are so small they are falling in the gap of rhinoās tolerance.
this is actually a pretty involved repair to get this right.
first step is to explode everything (yes everything) and change your tolerance to be .0001" itās currently .001"
then rejoin everything and look for naked edges.
there will be many.
then the next step is to run extractbadsrf (there will be many)
and rebuild or repair the bad surfaces using the techniques that I show in the video above.
this is an example of the tolerance donut hole problem-
these edges are all close enough they are smaller than the tolerance of the file, Rhino cannot tell them apart or sort them correctly and joins them wrong.
you can help it by joining these first so rhino has less to choose from-
then join those into the part.
but the better way is to screw your tolerance down a a bit so the problem is lessened.
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I took the liberty of fixing the one on the right so you could see what I fixed, partly to show you I wasnāt just making stuff upā¦ but itās also good practice for me to fix these type of issues and make sure they are not rhino bugsā¦ ā¦
Earring mold CNC_kfix.3dm (3.4 MB)
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working on teenie tiny things requires teenie tiny tolerancesā¦
and when you do that, the match command, the matchsrf command and the showedges command are going to be your best friends.
Thank you so much for the video! You used several commands there that I am unfamiliar with. I will work on it and see if I can get them all closed up! I appreciate the respond and education, it is invaluable!
Kyles of the world unite!
happy modeling-
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thank you for the reply! By coincident faces/edges, are you referring to two polysurfaces that will alight at the same point? As I am essentially creating a closed polysurface and then another closed polysurface with in it(often aligning it with the edges of the previous polysurface). Then I use the split/trim function to split the parts at the surface lines and delete the surfaces I dont want leaving cavities, etc. Then I use the Join command to put the surfaces back together to create the closed polysurface again. I feel like this method is time consuming but again Iām a noob soā¦
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Yes. But to make sure we are talking about the same thing, Iāve attached an image. The objects on the left have coincident faces. The objects on the right do not. Whenever possible (itās not always possible), avoid coincident faces/edges if you intend to do boolean operations later. (BTW, you can use the boolean difference tool under the solids tab to subtract the ācutterā from the larger objectā¦sometimes you have to resort to splitting, but boolean difference is much quicker, and you can choose to keep your cutter objects with the boolean difference tool, which I normally do, in case something goes wrong). And, I usually put my ācuttersā on a separate layerā¦which I normally give a bold, bright color like orange or red. If there are different types of cutters (the earring/sprue vs the relief slits), I might put the different types of cutters on different layers. Also, in some cases, you may want to save a version of your file before the booleans are done. Just whatever is necessary to quickly rebuild the object if a problem happens.
However, your main problem was the tolerance issue that Kyle pointed out (I didnāt realize that). So, even if you had not had coincendent faces, you still would have ended up with the same or similar problem. So, my tip was (possibly) good advice, but it would not have solved your problem in this case.
By the way, it looks like you do jewelry design. I did jewelry design for 10 years with Matrix (which is basically just a massive plug-in for Rhino). When I first started, we had a wax mill. We eventually went to 3d printing. If we needed to make injectable wax molds for some reason, we would 3D print the piece and cast it and then make a rubber mold out of that, with a vulcanizer. We didnāt do that often. We usually just reprinted the file. But then we mostly did one-off custom jobs. Wax molds (for the little jewelry store I worked at) was more a thing from the āold daysā when people used to hand carve wax masters.
Iām curious, what are you CNCāing the mold out of? Metal? Or something else?
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Great explanation! Yes this is exactly what I was thinking, and to date I have usually been doing things like the example on the left. I have not used boolean difference tool, it definitely sound =s like it would be faster. I like your layer advice as well. I tend to just keep working all in one layer and it does get confusing when everything is the same color.
As far as jewelry design, my wife and I own a company where we do cleaning up and recycling of ocean plastics. We take the plastics we find and make them into new products. So this mold will be machined from metal to injection mold earrings from the plastics we find. I have other designs I am making as well for other products but this is a start.
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If I understand your workflow correctly you might want to try the makehole command - MakeHole | Rhino 3-D modeling
Not always, but I often find makehole more efficient than Boolean difference when cutting inset shapes into a solid.
Other solid tools commands may be of interest also - Solid Tools toolbar | Rhino 3-D modeling
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@Kyle_Gerecke Oh, okay. Interesting. I did traditional (metal/gems) jewelry design.
@hughecchapman I myself never used MakeHole before. Cool.
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