HELP creating geometric shape for 3D printer

Hello,

I am creating centerpieces and these plaster of paris shapes are a pain to recreate. I have access to a 3D printer but am having difficulty creating this fairly simple geometric shape on my own. The top ans base are 3x3 square shaped, and it is about 6 inches tall, and the widest point in the middle is about 4 inches.

I was hoping someone could e-mail me the STL file for this shape. Dimensions don't need to be exact, I am just looking for this general shape. Any assistance would be greatly, GREATLY appreciated.

Thank you,



Attachment 15185Attachment 15186

is that two pyramids - base to base, attached to another base to base pyramid ?

basically two of these, stuck together along one of the faces ?
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Also dimensions are determined by the slicer before you print. You can make them anything you like :-)
Size of a model like this within a cad program is largely irrelevant.

More pictures wouild be useful - not entirely sure of the shape.
Is this close ?
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Thank you for your reply. This looks close! However the base in your rendering is a triangle and mine is a square at the base and at the top. Here is another image that may make it a bit easier to decipher.
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Also if you could limit the same thread to just one part of the forum that would be good :-)

lol - geometry was never my strong suite.

so you've got a square base with 8 triangles vertically mirrored to another 8 triangles and a square top ?

Ah - do you perchance know the actual angles of those triangles ?
That would probably help.

Actually what I need is the width of the base of the trinagles and the height of the triangle from the centre line to the apex.
That'll give me a proportionally corrext sized triangle. Which I can then rotate and tilt to make the actual shape.
In theory anyway :-)

Yup! I believe that would be the perfect way to describe this shape! :-D

I don’t know the actual degree of those angles but I can try to figure that out.

So the base is a 3” x 3” square, and it is 6” tall. So I think all those angles should be an even 60 degrees?

Wow, of all the images to have to view in 2D, those to photos are tough ones. I'm not surprised that Curious Aardvark is using OpenSCAD to generate it. It's by far the easiest method to create such geometry. If you get lucky, he'll give you the source and you can adjust parameters to your heart's content.

i actuallty just want the size of the triangle - in millimetres if possible.
they look taller than they are wide - although on balance it actually doesn't make any difference.

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If you get lucky, he'll give you the source and you can adjust parameters to your heart's content.

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'give' - hmm, 'sell' - more likely :-)

Let's go with 76 mm wide for each of those triangle bases. I'm not looking for it to be super exact to my plaster copy. Just this symmetrical on all sides geometric shape. :-)

how many f****ing triangles are there on each square ?
6 or 8 ?

I can see there's a trinagle with long base a,long the cube - but how many are there of upside down ones ?
It has to be another 4 right ?

Each time I look at that bloody model I see different numbers.

my brain hurts lol

I'm about 90% there, just having trouble matching the damn triangles up

At this point, I'd be opening Tinkercad and dragging pyramids onto the work plane. Griffinmcg, consider to do just that, to bring up a model that removes the confusion.

Haha, there are 8 triangles on the top half of the shape and 8 triangles on the bottom half of the shape = 16 total. Then 1 flat square on top and 1 flat square on the bottom. I thought it was pretty simple when carving it from cardstock paper but now the more I look at it, the more my brain begins to hurt - haha!

how's this ?
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going to print one - just because it's such a weird shape lol

That looks like it's a match!!

The weird bit that makes it strange to look at is that the trinagles on the long sidees lean outwards, while the upside down ones on the corners lean inwards.
And your brain doesn't believe they can meet up :-)

Tricky bugger - but I'm stubborn :-)

I made a video - first time I've ever made screen capture video. Windows game bar makes it dead easy :-)
it's fun :-)
And there will be more !
https://www.youtube.com/watch?v=Idq4...ature=youtu.be

I should have taken better photos from all angles before I left the house today, but it looks like you nailed it!

Great video! It looks perfect. Now how does one get their hands on that print file to avoid hours worth of mixing and pouring plaster? Haha ;-)

so what's it worth to ya ?
:-)

I have no clue. I’m a total newb just looking for a way to cut time on these centerpieces. What’s fair in this world? Haha

@curious aardvark, without giving away your valuable secrets, can you tell me what approach you used to create the shape? I can't see an easy way to make it parametric using primitives. I suspect you've accumulated a series of vertices, then generated the faces. If that's correct, is it parametric?

I'd like to understand, for example, how one could generate the base square parametrically with the appropriate point locations, then "elevate and rotate" the points for the next layer and the next, and then generate the faces. If that's not how you did it, do you think this method is valid?

I’m not sure how he mastered this in the 3D software - couldn’t for the life of me. But when I created my original mold I just drew out the angles on a large piece of cardstock paper then used a straight edge blade to perforate (not cut) the lines, then it was easily folded into the shape you see in pic number 3 and taped up.

Something like this?

Attachment 15201

I've put an STL here: https://drive.google.com/file/d/1vPO...ew?usp=sharing

This only took a couple of minutes to design in OpenSCAD.

This looks fantastic! I am having trouble accessing the file on Google Drive so I sent a request from griftwin gmail account. Thanks!

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Originally Posted by jamcultur

Something like this?

Attachment 15201

I've put an STL here: https://drive.google.com/file/d/1vPO...ew?usp=sharing

This only took a couple of minutes to design in OpenSCAD.

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Originally Posted by Griffinmcg

This looks fantastic! I am having trouble accessing the file on Google Drive so I sent a request from griftwin gmail account. Thanks!

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I think I just gave you access. Try this link:https://drive.google.com/file/d/1vPO...ew?usp=sharing

Do you have OpenSCAD? I can send you the script. It is set up so that you can use it with the customizer to change the width and height of the object.

It looks like this worked - thank you so much!

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Originally Posted by jamcultur

I think I just gave you access. Try this link:https://drive.google.com/file/d/1vPO...ew?usp=sharing

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Yes please do ! I do not have OpenSCAD but I can get it.

Quote:

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Originally Posted by jamcultur

Do you have OpenSCAD? I can send you the script. It is set up so that you can use it with the customizer to change the width and height of the object.

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Quote:

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Originally Posted by jamcultur

Do you have OpenSCAD? I can send you the script. It is set up so that you can use it with the customizer to change the width and height of the object.

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Is your code a state secret too? Something I can view and be illuminated?

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Originally Posted by Griffinmcg

Yes please do ! I do not have OpenSCAD but I can get it.

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I'll put it here in case anyone else is interested.

width = 76;
height = 130;
draw_one();
translate([0, 0, (height/2)-0.01])
rotate([0, 0, 45])
draw_one();

module draw_one() {
hull() {
cube([width, width, 0.01], center=true);
translate([0, 0, (height/2)])
rotate([0, 0, 45])
cube([width, width, 0.01], center=true);
}
}

When you run it with the OpenSCAD customizer, you'll get a very simple user interface where you can specify the width and height in millimeters.

Attachment 15202

Edit: Sorry the code lost its formatting when I uploaded it :(

Here's what the code should look like:

Attachment 15203

lol thought someone who wasn't broke would do that.
Clever way to do it too - way simpler than my method.
If only i understood geometry :-)

Added another variable to give you control over the angle of rotation, makes some interesting shapes :-)

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width = 76;
height = 130;
ar=100; // angle of rotation

module draw_one() {
hull() {
cube([width, width, 0.01], center=true);
translate([0, 0, (height/2)]) rotate([0, 0, ar]) cube([width, width, 0.01], center=true);
}
}

draw_one();
translate([0, 0, (height/2)-0.01]) rotate([0, 0, ar]) draw_one();

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