Printing tiny parts in high definition

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Printing tiny parts in high definition

Postby nycdude777 » 2016-Dec-Sat-21-Dec

Hey guys,

I just made this sudden discovery. It's been on my mind for a long time. I've always been fascinated by the idea of creating something on a large scale and then somehow miniaturizing it to nano scale while preserving all of the finest details. Cuz let's face it, it's hard to make complex parts working on a small scale. Well, at least before Nanoscribe it was, check that out ;) too btw, it will knock your socks off...

But here is what I realized, you can create a part from a porous material like styrofoam and then pressure cook it for 10 minutes, and bam, all the air gets compressed out and it retains its compressed shape because of high temperature!

So I carved out some parts from various porous materials I could find laying around, and cooked them all at the same time. Project Panel from Home Depot, which is the rigid insulation board about 1" X 2' X 2' they sell for 5 bucks turned out to be the best of what I had. Check out the before and after pics below.

There are the Parts I carved out using a cardboard cutter, and a rotary tool. I wanted to see how different materials and shapes responded.

Before:
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And here are the first results:
image.jpeg

Notice that the biggest holes here were the same diameter as the widest part of the cone bit I used to carve them out!

More pics
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image.jpeg


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When it dried, it was very light and very rigid. It felt like a piece of balsa wood and made the same sound of dropped. Easy to work with if you need to sand it or polish it.

Now, there were some deformations, and I noticed that the pulley wheel escaped from underneath a wire mesh I made in the pot to keep everything submerged and was floating when I opened the pot. So it's very important to make sure they are submerged. However, you can't clamp anything down or insert like a pin or something to secure it, any deformations will get exaggerated and will result in Picasso melting clocks.

Now, what does this have to do with printing you ask? Well, everything. I dont want to carve these parts by hand, I want to print a part and then miniaturize it.

Two ways I see from here, one, try to print with porous filament, I found one I can't remember the name of, but what I don't like is you have to soak it first for like a day and have the soluable filler wash out, leaving behind the air pockets, and when I looked at the pictures closely, it didn't seem like there were enough pores, like in foam, so I'd say it won't compress as nicely.

The other option that I'm thinking now is, print the part using PLA, make it very dense, then sand it and polish it, make it look the way you want your final part to look like, and then create a silicone mold with it. Then fill the mold with expandable foam, I just got a can of Great Stuff at Home Depot, gonna try that, it feels very soft and compresses easily to the touch when dry, which tells me it will compress even better than the rigid insulation.

I'm just worried about how dangerous that stuff is to cook, poisons and stuff, vapors... Not that its flammable past its curing stage.

And also, important to think about, is that any variations in density across the body of the part, like on a surface, created by overheating tool bit, or glue, or compression from clamping, will deform the part during cooking.
I'm wondering if the expandable foam, when filling out the mold, will create a nice and equal distribution. It should right? Why would it stick to a corner and keep building up pressure, it should percolate nicely and ooze out in excess.

Anyway, I am going to continue experimenting and keep updating the thread.

I hope you find this useful, and if you have any ideas or thoughts please do share!

Rick
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Printing tiny parts in high definition

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Re: Printing tiny parts in high definition

Postby nycdude777 » 2016-Dec-Sat-22-Dec

I just realized I missed a picture of the compressed cylinder with ridges, here it is

image.jpeg
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Re: Printing tiny parts in high definition

Postby DonaldJ » 2016-Dec-Mon-21-Dec

A few years ago I spent a lot of time playing with the Great Stuff expanding foam and there are a few things I've learned.

It cures with exposure to air and the internal foam structure can be very uneven. A useful trick is to spray some foam in a disposable container (polypropelene is very good) and add a little acetone (a few drops), mixing thoroughly. This collapses the foam and will allow you to pour the mixture into a mold and give a more dense internal structure. The foam will slowly continue to expand and eventually cure as normal. It's tricky and trial & error are your friends; It might take days to cure completely.

Have plenty of acetone on hand; it cleans up easily before it's fully cured. You'll be able to use the nozzle assembly more than once. The cured foam doesn't stick to many types of plastics, including nylon and the aforementioned polypropelene, but you should conduct your own tests with the materials you have on hand as my memory may be faulty.

Please follow all the safety instructions, especially regarding ventilation.

Two-part expanding foam is available, but you will need an accurate scale; it's about a 10:1 ration by weight, if memory serves. But the foam structure is much more uniform, it's available in varying densities, and you don't have to worry about exposure to air affecting the cure.

But wouldn't it be a lot easier printing with a smaller nozzle size?
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Re: Printing tiny parts in high definition

Postby nycdude777 » 2016-Dec-Sun-11-Dec

Actually I am printing with a 0.2 mm nozzle that i made, the quality of prints is very good. I'm in the process of manufacturing a 0.08 mm nozzle now. What I was trying to do is go even smaller.
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