Cheap, 3d-printed inner grids

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kvedera
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Cheap, 3d-printed inner grids

Post by kvedera » Tue Feb 05, 2013 4:47 am

I know I've been overly active over the last few days, and I'm sorry for hogging the airwaves (this is my last post) (probably).
I just wanted to inform you friendly fellas that I put up a design on Shapeways.com for a inner grid, so if you want a perfectly symmetrical and circular inner grid just follow this link:
http://www.shapeways.com/model/907221/i ... =my-models
(The picture's a little perspectively misleading, look at the 3d animation for full view)
So yeah, just get a stainless steel one of those printed, and bob's your uncle.
Best of luck in all your endeavors,
Anthony Kveder

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Chris Bradley
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Re: Cheap, 3d-printed inner grids

Post by Chris Bradley » Tue Feb 05, 2013 7:30 am

The surface roughness from a 3d print would probably mean that it will be sparkling and 'electro-cleaning' itself for ever.

kvedera
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Re: Cheap, 3d-printed inner grids

Post by kvedera » Tue Feb 05, 2013 11:32 am

Yeah, maybe. It was just an idea.

kvedera
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Re: Cheap, 3d-printed inner grids

Post by kvedera » Tue Feb 05, 2013 11:32 am

Anyway, is that really that bad?

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Chris Bradley
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Re: Cheap, 3d-printed inner grids

Post by Chris Bradley » Tue Feb 05, 2013 6:53 pm

Try it! There seems to be little to be gained by having a perfect grid, however, but that is not well researched - a few anecdotes either way. A printed grid would likely provide some much needed consistency between different grids, so as to see what forms compare with what.

Spark-erosion is one means to perform very accurate engineering, so maybe it would all come good once this printed grid 'settles in' and all the asperities are burnt off.

Some fusing of the pieces will also, likely, happen making it more solid, but possibly distorting your perfectly shaped grid as the micro-voids drop out of it. By the time it has burned in, internal distortions and external erosions might mean that the geometry is just as uncontrolled as a wire grid!

... but, yeah, do try it if you are motivated and can do it! I'm sure you will get due kudos here in the attempt, whatever the outcome.

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Rich Feldman
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Re: Cheap, 3d-printed inner grids

Post by Rich Feldman » Tue Feb 05, 2013 8:00 pm

Yes, Anthony, start getting your hands dirty!

I'm sure many readers would love to see pictures & cost data of a 3d-printed grid. If you get one or more made, maybe someone else could try it in a working fusor for you.

Another option for a symmetric, seamless, reproducible, spherical grid
would be to start with a thin hollow sphere, such as a stainless steel float.
Then machine or etch away unwanted material.

You are free from the constraint of overlapping great circles.
Why not make a grid not easily done with wire?
How about a soccer ball (buckminsterfullerene), or the pattern from some other familiar sports ball?
All models are wrong; some models are useful. -- George Box

kvedera
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Re: Cheap, 3d-printed inner grids

Post by kvedera » Tue Feb 05, 2013 9:27 pm

Ah, good point! Thanks guys, I'll try that out. Unfortunately I won't be able to give results, because I haven't actually BUILT the damn thing yet, but I ordered the grid, and modeled a new buckyball-shaped one to try out. Thanks for the encouragement.

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Richard Hull
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Re: Cheap, 3d-printed inner grids

Post by Richard Hull » Tue Feb 05, 2013 10:18 pm

All grids made of metal suffer extreme hydrogen imbrittlement over time. I have mentioned this before. Thus, springy grid wire forced into loops and circles, as in the normal construction, gets to such a degree of embrittlement that it winds up like a piece of glass, hard, brittle and forever formed into the geodesic.

I silver soldered my first grids together back in 97-98. I worried that the heat would pop the circles loose so I babied them along, never allowing them to get red hot. Over time, I noted that the silver solder was gone or seemed to have disappeared, yet the grid stayed intact. Finally, I did over temp a grid to a degree that a section of one of the geodesic wires melted and fused to two beads on each end of the wire arc.

I removed the grid and studied it. It was frozen and so brittle that a pair of pliers allowed me to snap off the melted arc sections without harming the rest of the structure or poping the loop open.

We observe that a process that would normally be considered a route to structural failure, turns out to be beneficial in this one instance.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

kvedera
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Re: Cheap, 3d-printed inner grids

Post by kvedera » Tue Feb 05, 2013 10:54 pm

So, do you think this would impair the efficiency or structural soundness of a 3d-printed one? It's made from powdered stainless steel, and has about 30% bronze mixed in with it. If you look at the one I made, it's pretty thin (I'm beginning to regret making it so thin, I may make another one). Might hydrogen imbrittlement damage it to the point at which it is almost useless? Be aware that it is not soldered together, but it simply one singular mesh of wires.
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Inner grid.jpg

kvedera
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Re: Cheap, 3d-printed inner grids

Post by kvedera » Tue Feb 05, 2013 10:56 pm

Also, as I mentioned, the perspective in this picture makes it look like it has a rod running from one pole to the other -- this is not the case. The thing that looks like a pole is simply another ring, viewed sideways.

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