Please find attached a file (KleinTeil) of an object which I tried to fillet, first as a solid, then surfaces, then edge(s). I tried various options: circular,… but without success.
However I was able to shell this object.
Unfortunately the sharp edges cause problems with 3D-printing.
Is there something I could do to fillet this Object?

I have then 'rounded' the object (see file KleinTeilRounded) which I tried to shell with a thickness of 2 mm.
The calculation started but stopped without producing the shell.
I tried different thicknesses with the same outcome.
Is there some other possibility for creating the shell, which I would like to 3D-print?

thanks & regards
Jurgen

Just idea
Maybe there is something to do with export the perimeter : join it
make 3D scale
make a full tube
Boolean Merge the tube with the volume
kill that you don't want
(scale 3D is not made here)

Thank you for your suggestion, Pilou.
I joined the edges and was able to sweep a tube.
Then I 3D-scaled object and tube to the same size, but I could not align them 'concentrically'
Is there any align to 'center' possibility? Or any other way for the merge?
Thanks & regards
Jurgen

Hi Jurgen, I'm not 100% certain what's going on there, but it may have something to do with these areas of your model where you've got opposite sides of the model coming down to meet each other flatly:



Having that area collaping down exactly to the same tangent there may not be a good thing, because it means there is a small area where the upper and lower surfaces are overlapping each other, and self-intersections between different surfaces in a solid is not a good thing to have.

You might have some better success if the curvy piece ended with a little bit of an angled tangent leaving some small volume area in those tips rather than having the curvy piece come down to exactly the same tangent direction as the straight piece making for a totally flattened area there.

- Michael

Hi Jurgen, yeah I think those thin tips that come to an exactly flat spot from opposite sides are causing the problem.

I did a quick experiment where I hacked those tips with a plane and then that allowed me to put a small fillet on things.

But you probably don't want cuts at the tips there so you may need to make those tips come to something more like a 20 degree angle at their ends rather than coming to a 100% sharp flat tip.

- Michael

I was fooling around with it a bit and a .01 fillet consumed almost the entire area back to the vert!!!!!!!

Hi Michael,

I was able to apply a .2 Fillet to your 'KleinTeil clipped', but I was not able to separate the 'desired object' from the 'border' cut away, i.e. I could not DELETE the 'border'.

First method: I did HIDE the 'desired object' and DELETEd the 'border', did SAVE AS the 'result', but when I reopened the 'result', the 'original object' appeared.

Second method: I clicked on and EXPORTed the 'desired object', but when I reopened the 'result', the original object appeared.

Is there another method?

Could you please have a look at the second file I originally attached ('KleinTeil rounded').
Here I tried something similar to the clipping you applied, but I could not FILLET nor SHELL this object (filleting would not be required for this object).

Is there a possibility to shell this Object (, which would significantly reduce the cost of the 3D-print)?

thanks & regards
Jurgen

Hi Jurgen,

> Could you please have a look at the second file I originally
> attached ('KleinTeil rounded').
> Here I tried something similar to the clipping you applied, but
> I could not FILLET nor SHELL this object (filleting would not be
> required for this object).

The problem with that one is your clipped areas are very small slivery surfaces, like this:





That's bad for filleting because you are limited to only use a maximum radius that will fit around that little slivery face there without eating it all away. Because that face is so small, the radius limit will be very very small in this particular case.

That's why it is probably better for this shape to be created with larger surfaces but where the surfaces meet each other with something like a 20 degree angle instead of coming to a completely flattened 0 degree angular difference from opposite sides.


Little slivery surfaces like your clipped version will be a problem for shelling as well.


> Is there a possibility to shell this Object (, which would
> significantly reduce the cost of the 3D-print)?

Your original model seems to shell ok over here - I tested loading your KleinTeil.3dm model and running Shell on it with a thickness of 0.5 units, and that creates a hollowed out shape, I have attached the 3DM file result KleinTeil_shelled.3dm

If you do a boolean with that object with a line and move the parts you'll see it has thickness, like this:



It's best to do the shell on the object before you do any fillets on it - if you put fillets on first then that creates more things that the Sheller has to process.

In a worst case scenario for removing internal volumes, you can just model some rough shapes and put them inside the model and use boolean difference to make them cavities within the main shape - that will also work to make hollowed out areas within your shape you don't have to only use shell for that. Shell is convenient but it's best to give it the most simplified version of your shape for it to have the best chance, meaning no little slivery surfaces, no little tiny fillets - put on things like that after the shell instead of before it.

- Michael

Maybe you must round pikes parts before fillet :)

Hi Jurgen,

> I was able to apply a .2 Fillet to your 'KleinTeil clipped',
> but I was not able to separate the 'desired object' from
> the 'border' cut away, i.e. I could not DELETE the 'border'.

Hmm, yeah at some point it was working but not after I saved and reloaded the model.

When you get a fillet that has this odd border thing in it, it means that the filleter was able to generate fillet surfaces but it ran into some kind of error when trying to trim the main object when cutting it with the fillet surfaces. It returns the generated surfaces in this case so that you may have a chance to do some work on things to salvage them.

It seems to be having some additional difficulty in this area of the model here:



It's actually not so good for filleting when both sides of the edge are curved surfaces to have edges join to a common point like that, because fillets work by a kind of surface offset and that means that one fillet goes like this:



And the other fillet goes like this:



So that leaves a kind of gap area between the fillets that the filleter has to deal with filling in, and the filleting engine seems to have some difficulty handling areas like that.

If you zoom in on this area of the fillet surfaces you will see a kind of problem area:





It's possible that if that connection piece is repaired (like maybe just deleted and a loft put in between the ends of the other longer fillet pieces), that it could then be used to trim the main object succesfully with the Trim command to incorporate the fillet into the main object.

- Michael

Hi Jurgen,

> I was able to apply a .2 Fillet to your 'KleinTeil clipped',
> but I was not able to separate the 'desired object' from
> the 'border' cut away, i.e. I could not DELETE the 'border'.

I've attached a version here that has a 0.2 radius fillet applied to that "KleinTeil clipped" model version.

I had to do some repair work on that one area I showed above (also the fillet piece from above needed to be untrimmed, the filleter had incorrectly trimmed the fillet back a little bit too much making it stop short of the surface edge), and then trim the various surfaces of the main body to the fillet edges and then join all the pieces up to a solid again.

To make this version shelled, you'll actually want to go back to the original unclipped model, and use the Construct > Offset command with the "Flip" option checked to create a sort of inner core piece. Then take this filleted model and use the boolean difference command and select that inner core as the cutting object, and that should result in a hollowed out cavity within this shape to save on materials. Use window selection (where you click in an empty area and then hold down and drag to make a selection rectangle) to select the inner piece in the boolean difference command, since it is not easy to click on it since it is contained within the main piece.

Hope this helps!

If you don't like the clipped areas in this version, your best bet may be to delete those faces in this model version and construct some new surfaces in those local areas.

- Michael

Hi Michael,

Thank you for your explanations. I understand FILLETing now much better.
I was able to SHELL KleinTeil.3dm too and have submitted the shell to the 3D-Printing company.
I will receive the result in about two weeks and could show it here, if this would be of interest.

>for removing internal volumes, you can just model some rough shapes and put them inside the model and use boolean difference to make them cavities within the main shape -

I will follow this very helpful suggestion, which meets my objective of reducing 3D-Printing costs :-)))

thanks & regards
Jurgen

Seems you must round the pikes for have a more hamonious form :)

Hi Michael,

Thank you for the explanations and the repair work.

I always wondered why the straight lines on the model are there, as the model has essentially only two continuous surfaces.

I there any way to remove those lines? This would probably reduce the repair work.

thanks & regards
Jurgen

Hi Jurgen,

> I always wondered why the straight lines on the model
> are there, as the model has essentially only two continuous
> surfaces.

Those lines are the edges between the different surface pieces that make up the model. Even though your overall form has a continuous surface, your particular model construction is made up of several surfaces that are joined together at shared edges.

Usually that kind of structure is the result of the segments in your original curve structure coming through. For example if you have a curve that is made up of 2 segments joined together, when you extrude it you will then end up with 2 surfaces joined together following the same segment structure as the original curve.


> I there any way to remove those lines? This would probably reduce the repair work.

There isn't an easy way in MoI to remove them after you've already got it all constructed - it would require merging the separate surfaces together into a larger single surface. I do plan on adding in a tool to MoI in the future that will do that.

You can avoid those being created in the first place if you make your original curves be long single pieces instead of constructed of multiple joined segments. The Rebuild command can be a good way to build a new single segment curve out of a multi-segment one:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#rebuild

- Michael

Hi Pilou,
thank you for your suggestion.
I have done this already (see the file 'Kleines Teil rounded', which I originally attached).
See the replies concerning this version.
regards
Jurgen

Hi Micheal,

>I do plan on adding in a tool to MoI in the future that will do that.

I am looking forward to get this tool.
Until then I'm happy with what I can achieve following your suggestions.

I will try the REBUILD command when creating my next masterpiece ;-)

thanks again
Jurgen

Ah, sorry, i had only loaded the normal file :)

Hi Michael,
I have applied a 100 points Rebuild to the Curve around this Solid.
How could I create a Solid with this Curve (like the original Solid)?
How could I create surfaces with this curve (like the two surfaces of the original solid)?
thanks & regards
Jurgen

Hi Jurgen,

> How could I create surfaces with this curve (like the
> two surfaces of the original solid)?

Right now it looks like you're trying to think of following the 3D curve that is swooping around in 3D space.

Instead try to focus on the 2D profile aspects of the shape and try to figure out how you would create some 2D curves to construct it.

So for example note that these side surfaces are straight in one direction:



That kind of straightness usually implies an extruded surface, so to build something like that, get a flat profile curve drawn in one of the 2D Top/Front/Right views that looks like this:



Then you can Extrude this to build the base underlying shape, like this:



Now you want to remove some of that material, create some side profiles something like this:





Now you can use a boolean command to slice the extrusion with that side profile, in this case use the Boolean Intersection command - that will only keep the area from the extrusion that is also inside of that 2D profile curve, like this:



It's also possible to run boolean intersection just directly on the 2 planar profile curves, it will automatically do the extrusions for you, see the help file topic for an example:
http://moi3d.com/2.0/docs/moi_command_reference7.htm#booleanintersection


But basically you can get stuck pretty easily if you're trying to think about how to create something following contours that are swooping around in 3D - instead of thinking like that, try to imagine some larger uninterrupted forms of the object, and build those as some larger initially more simple extended piece (like the extrusion above), and then get your final shape by cutting that object with other profiles to remove material from it.

Basically try to ignore things that look like cut out areas for the first stage of figuring out how to build the basic shape - build a bigger piece first and then make the cut out areas happen by slicing that shape, rather than trying to do something like try to sweep directly along complex 3D swooping boundaries or things like that.

- Michael