Instructables
Picture of How to use Google SketchUp for Ponoko 3D printing
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This Instructable covers making a 3D file in SketchUp and then exporting the file so that it can be printed up by Ponoko.  The item being made here is a level-3 Menger sponge.

This Instructable is an entry for the Google Ponoko Challenge. It ends tomorrow, Dec. 17, so if you have an idea for an entry do it soon!
 
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Step 1: Starting with a cube

Picture of Starting with a cube
The Menger sponge starts with a basic cube. In theory you would be subdividing each face into 9 pieces and then "pushing through" each middle face to create a hole. This technique would work fine for the first iteration, but become a huge problem in the 2nd and a massive headache for the 3rd. Instead it's easier to build up.

Step 2: Build the 1st iteration

Picture of Build the 1st iteration
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Make the single cube a group. This prevents the cubes from attaching when you copy them.

Now copy and move the cubes so that you have 8 in the arrangement seen in picture 2.

Group these 8 cubes and make 2 copies stacked on top of the first layer.

In the middle layer, delete the 4 non-corner cubes.

You should now have what's in picture 5 here. This is the first iteration.

Step 3: Explode and erase

Picture of Explode and erase
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Select everything and explode the model. Do this twice and all the cubes should now be connected.

Now use the eraser tool to remove the internal lines in the model. Picture 2 here shows one side cleaned up.

Step 4: Second verse!

Picture of Second verse!
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Make the new model a group and repeat step 2.

 - Make one layer
 - Group it
 - Copy it
 - Delete 4 squares in middle layer
 - Explode x2
 - Clean up with eraser

Step 5: Third verse!

Picture of Third verse!
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OK, you know what to do next, repeat step 2 again!

 - Make one layer
 - Group it
 - Copy it
 - Delete 4 squares in middle layer
 - Explode x2
 - Clean up with eraser
:O so cool!
dscott43 years ago
Hiya

I would love to see it added to the 3D print group I have just started

http://www.instructables.com/group/3Dprint/

Thanks
This is very interesting!
What did this cost for example?
Yes what did cost???
tinker2343 years ago
cool hey yo semm good fungas with sketch up could i make a game using stuff from skethup tanks tinker
dyly3 years ago
I want a 3D printer so bad!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Nice Menger Sponge!
It would be so awesome in gold plated steel.... epic win!
Wood Chuck3 years ago
I just drew this up in Sketchup - it took about 30 minutes. I also have Alibre, but I find it too complicated, Sketchup is fast and easy to use.
http://sketchup.google.com/3dwarehouse/details?mid=2fb27d07c11af89eeae3eee872e388f6
Bruce
That's funny, I just drew it in SketchUp in one second. I'm not kidding. Of course I had a little help from this plug-in ;) :

http://regularpolygon.blogspot.com/2010/08/plugin-menger-sponge-10.html

MaXoR Laral3 years ago
lol.... guess there is the hard way (alibre), easy way (Sketchup by hand) and the "punch who through what?!?!?" way (Plugin)
I just downloaded that script, it looks like fun :)
fungus amungus (author)  Wood Chuck3 years ago
Nice!
smkoberg4 years ago
I love it!
Just out of curiosity, how big is the finished model, what material did you use for the final model, and do you have them available for purchase on the pokono site? I want one!
fungus amungus (author)  smkoberg4 years ago
This model is about 1.4" on each side, made with the "durable plastic," and I don't have them available for purchase currently. It's pretty easy to make your own, though, and then you can tweak the size.
lol....you sound like a broken record.... need a web page set up to just send them to?
Laral3 years ago
This is really neat. I never heard of Ponoko. It's a good idea but it seems expensive. How much did this small model cost? What do you get for the money? Does it come in cut sheets or do they assemble it for you? I'm sure I'm not the only one who has these questions.

As for 3D CAD programs, I've used most of them, including Sketchup. I found Sketchup really almost impossible to use to do anything. OK, it's free but . . . The major CAD programs have all kinds of features that make doing repetitive tasks, like this, easy--once you learn how. They are difficult to learn, admittedly, but so is Sketchup, frankly. That would be just about my last choice. Considering how hard it is to use, you did a great job. Kudos!
fungus amungus (author)  Laral3 years ago
It's 3D printed so it arrives just like you see it, one solid piece. This is 1.4" on a side and cost $26 for production and materials, plus more for tax and shipping.

I've used a few different 3D CAD programs, although not extensively, and each has different uses. SketchUp is, like the name says, good for sketching. I've seen it used in architectural consultations, for example.

I think that if your uses are more intense it wouldn't be something you'd turn to. In the DIY space it's very useful.
Holy cow! $26 for a 1.4" cube?
fungus amungus (author)  Javin0073 years ago
Yup. What can I say, I'm a math geek and wanted a Menger sponge.
lol
Laral3 years ago
Hey you won! Congratulations!

"Congratulations to Ed Lewis, aka Fungus Amungus, who created an all-around fantastic Instructable for using Google SketchUp with Ponoko 3D printing to win the Google + Ponoko Challenge"

http://blog.ponoko.com/2010/12/21/announcing-the-google-ponoko-challenge-winner/

Now let's see this in gold-plated stainless . . . LOL
fungus amungus (author)  Laral3 years ago
thanks!
Jayefuu4 years ago
Interesting that you chose to build it up rather than start with the final sized cube and just push square cuts through the cube then repeat the feature for 2 more faces. Perhaps it's just a difference between Sketchup and the software I use?
fungus amungus (author)  Jayefuu4 years ago
For the first iteration you could go either way and the difference in time is minimal. For the second iteration, there's a sizable advantage to building. For the purposes of the Instructable it's easier to just discuss one technique that repeats.
I mean... start with the whole cube, not 1/729ths of it then cut 81 small squares all the way through 3 faces, then 9 medium squares all the way through the 3 faces, then 1 big square through the 3 faces. I just found it interesting you did it your way not that way, since it looks like it shows the difference between the mechanics of SketchUp and the program I use, Alibre.
fungus amungus (author)  Jayefuu4 years ago
We're still talking about the same thing. For building, each iteration is a construction. For subtracting, each iteration is making a set of squares to punch through.

For your technique, you'd need to push through 192 small squares (64*3), 24 medium squares (8*3) and 3 large squares for a total of 219 pushes through.

I've never used Alibre, but on SketchUp it would take me far longer just to set up one face of small squares to push through than to make the whole model (about 5 minutes).
I wonder how much easier it'd be in openscad?

it'll probably just end up as a parametric mess of for loops...
A parametric OpenSCAD version:
http://www.thingiverse.com/thing:5321


size = 99; //side length
level = 3; //menger level

intersection(){
rotate([0,0,0])translate([-size/2,-size/2,-size/2])singleSide();
rotate([0,90,0])translate([-size/2,-size/2,-size/2])singleSide();
rotate([0,0,90])translate([-size/2,-size/2,-size/2])singleSide();
}


module singleSide(){
difference(){
cube(size);
for(i=[1:level]){
for(j=[0:pow(3,i)-1]){
for(k=[0:pow(3,i)]){
translate([-size/2,j*size/pow(3,i),k*size/pow(3,i)]){
//echo(round((j+2)/3)==(j+2)/3);
//echo((j+2)/3);
if(round((j+2)/3)==(j+2)/3){
if(round((k+2)/3)==(k+2)/3){
cube([2*size,size/pow(3,i),size/pow(3,i)]);
}
}
}
}
}
}
}
}
all in all it will be six one way and half a dozen the other. You really just need to do thinngs the way you are comfortable with and feel will get the "right" results. I agree with time saved by building up. I can copy and paste faster then placing all my squares to push. This instructable opended my eyes to a new way to have my prototype made up. Thanks for this ible. and BTW. what the heck did you happen to use this for? and what was it made out of?
It would seem it definitely depends on the software then! Alibre has some neat "feature repeat/mirror/rotate" features that probably mean the difference between spending HOURS drawing little squares and not. Perhaps I'll document the steps to show the difference if you're interested Ed.
There probably is a lot of difference between programs that can be used to make this type of 3D model, but the instructable itself is about SketchUp. Speaking from experience with this program I can say that building up is a lot easier than pushing the holes through. Not only would you have to push out all of the smaller holes inside the model (which would take a lot of attention to detail and leave a lot of room for error), but you would have to do so on every single side, 219 times for a level-3 Menger sponge as fungus amungus stated. That whole process could take hours, but it only took me about 20 minutes to make an entire level-4 Menger sponge by building up (even with a slow computer like mine).
fungus amungus (author)  OfficerKarl4 years ago
True, and that 219 number isn't the whole story ether for SketchUp. Once one side has been pushed through and created holes, the other sides won't push all the way through the entire cube, just to the next face.
fungus amungus (author)  Jayefuu4 years ago
Sure. I've never played around with Alibre before.
fungus amungus (author)  mikesnyd4 years ago
Cool, glad the info will help you out. This is just being used as a decoration on my desk. I like fractals and figured it would be nice to have one. This is made out of the "durable plastic" available on Ponoko.
Kaffe3 years ago
We made these in my Mathematics for Design class. We took old business cards and made millions of small cubes and then stacked them together.
Nice