Hollowed out now it costs 5x more :(

Hey all,

I'm completely new to CAD let alone 3D modeling but I fumbled my way creating a center console for my car.

I am using Blender to export as .STL. I think I just don't understand the proper technique in hollowing out the object.

Any help would be appreciated.

Here's the models:
https://www.shapeways.com/model/832044/
https://www.shapeways.com/model/832038/

You've got both models set to private.. we can't see them.

Oh doh, I checked the enable download sorry let me fix that.

I attached the .stl as well. FIrst message has the blender file. To hollow it I just deleted all of the "bottom" faces.

The model wanted cleanig up a bit. The wall thickness is 3mm. It will be expensive at that size. 302.41 cm3.
I would try to reduce the wall thickness down to 1mm
There are a number of ways in Blender to do this. One way is to make the model with just an outside skin and apply the modifier - solidify to 1mm.
Upload as mm.

Well it does have a hollow section at least.. Butou have some face normals on the outer surface pointing inward and outward, same for the interior. Outer surface face normals need to point outward, inner surface face normals point inward. Also in edit mode, deselect all, then select non manifold vertices. You will see several light up near the upper edged rim. Has intersecting faces and edges which is not good.

To determine face normals that pointing incorrectly you can either select display face normals in N panel, or select the bin, select object data. Deselect doublesided. Any faces in edit mode with dark faces the normals are pointing the wrong direction. Select faces with wrong facing normals, click flip normal in tool panel. I take it you were trying to get a height of 7.874inch / 20 cm. in z axis. The normal problem is what caused the increased cost.

I think the bevel you created caused the mess. Anymore questions just ask

Keith

Guys,

Thanks so much for your help! It's pitiful I don't know what you guys are even talking about in some areas hah! Feel free to point me to some "3D Printing for Idiots"

I failed to mention the application so it'd be great to have you guys chime in with your experience. This bin slides into my center console of my car and it just holds things, the lip keeps it from falling through. My original thought was to just have the plastic "solid" so I built a "water-tight" object so really what you see hollowed out should be sintered (if that's the right word). Anyway, bad idea, it's expensive (obviously ). I'm replacing the 6 disc changer shown here:



Here's what I'm confused about.
[list type=1]
[*] How do I know what the machine will make solid (or not)? Is this related to face normals?
[*] What are the steps in using netfabb because I brought into that app, the whole thing was red, then when I repaired it disapeared
[*] Are you setting the wall width in Blender?
[/list]

Again, feel free to point me to some tutorials, I've surfed around quite a bit and again this is what I came up with in about 4 hours.

I tried your repaired model. Did you just run it through netfab or did you make the adjustments you mentioned? The reason I ask is it's the same price as the original model I uploaded.

Here's a picture of the cd changer, we are kinda just make a hollow version of it:

I repaired it in Netfabb, by deleting some faces and creating new surfaces.
When you click on the Red Cross to repair, there are a number of options to select and repair traingles. faces or shells
You then need to Apply Repair, then Export Part as STL

Made this in Autocad . Took me all of five minutes. The wall thickness is 1mm. The holes in the top are to let the excess powder out of the rim.
It works out at 103 cm3.
You are welcome to it.
Gratis.

To better explain normals, they explain to the printer where the material lies, In this case I took a cube and deleted a face. Applied the solidify modifier to give it a thickness. Now consider it is hunk of plastic . I tried to paint the outer surface green, where the face normals were correct, and its interior yellow, where the face normals were correct also. The gray faces were where the face normals pointed in the wrong direction. I had to flip them in the Tool bar in blender. Then they could be painted the correct color.

Well before I fixed it, took a hacksaw to it and cut it in half. The pinkish area is the area where the material goes. Notice no faces. This area has to be open to let the printer know where the material goes.

But you can see the face normals if oriented correctly tells the printer where the material is supposed to go. To be able to print you have to be able to paint all the surface areas.(Painted the yellow faces green once it was fixed, and glued back together,lololols) Watertight explanation makes more sense, but same principle.

Keith

Thanks Keith. You've raised another question when you "cut" the box.

If I stacked two objects that occupy the same space on top of each other would the 3D printer know to sinter the item together?

In other words if you set your two pieces of the box back together without trying to create faces or sides would it know they are to form the cube?

Indirectly I'm asking what should I do to connect the "upper lip/face" to the box and keep the "upper lip/face" hollow (at 1mm).



EDIT:

I think I am confusing the heck out of myself trying to figure out what vertices/edges I can reuse from the box in the "upper lip/face." Though I've concluded that the outermost vertice of the "upper lip/face" has to connect to the box. I've also concluded that there has to be a inner face for the "upper lip/face" that is 1mm above the box.

This the mesh showing how you could salvage the lip of your model. The inner edge needs to be extruded 1mm less the length of the section of the other section(19.1) Then fill the open end you extruded. Check normals. The face normals of the newly created faces need to point inward, the other faces outward. Now select the outer outlined edge, extrude 1mm more than the last extrusion, fill the face, make sure these newly created faces face normals point outward .

With the lip, if you can make it so that the main body of the bin intersects with the lip (even by a fraction of a mm), Shapeways Mesh Medic software will merge the two parts together as one so long as both parts are watertight in their own right. NetFabb Cloud Service will also perform this operation and allow you to download the 'fixed' model - two good things about that service, 1, its free 2, it does a really good job of boolean additions.

Paul
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So 1mm wall thickness huh? I've been reading the tutorials on here and it says to go at least 2mm. They give examples too, and its case by case. I've been going back and forth between these thickness making the 3D models and it's driving me nuts!

wsf is a fairly flexible strong material. You could get away with 1 mm. He was trying to lower cost a liitle. To be on the safe side though , always create a thicker wall thickness for the more brittle materials than the guidelines suggests.

Keith