IW blower 4 - 3d printing test

Description

Compared to a multitude of previous blower models, this one involves 3d printing, which gives much better control of the configuration.

Corona discharge around thin wires puts ions into air. Then, ions drift towards the other electrode. As the ions impinge the air, they transfer some momentum to it, that is, creating pressure.

Details

This project is a subproject of #Ion wind loudspeaker experiments.

The main aim of this particular blower was to evaluate, is it OK to use 3d printing. You now... PLA!

I was afraid that corona wires heat up seriously, and they might melt plastic they are pushed against. Also, who knows, maybe the plastic is conductive a little bit.

Second thing is that 3d printing with exposed sparse infill can potentially make the whole structure completely sound-transparent, which is good news. So I wanted to try, how well complex models with overhangs can be printed made only of sparse infill.

And here come the results.

The basket is almost completely made of sparse infill with no perimeters (big thanks go to Slic3r, which allows to apply special settings to selected geometrical parts of the model (aka modifier meshes)). It prints good enough.. not fantastic, but perfectly adequate for the purpose. Win!

Still haven't got the basket and baseplate mating system. Had to hack on some screws to hold the two pieces together. In the background, you can see high-voltage multiplier of my high-voltage power supply.

So far so good. I had it blowing for a minute or so, and corona wires don't seem to melt the plastic. This is good news, but if it arcs, the meltdown is guaranteed. Gonna try that, but a bit later.

All model files can be downloaded from my google drive: https://drive.google.com/file/d/0B9lBm-SSD5KSSE9FS0Fob3ZtR0U/view?usp=sharing

Project Logs

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trying to make some sound
DeepSOIC • 10/15/2015 at 22:18 • 0 comments

This is the first attempt to play some music using this new ion wind blower. Yes, I did not try switching it on before pressing record. Well, I have set up the amplifier, though, it required some tweaks.
So I got some sound. But sparking is a big problem. The blower works very well at DC. But as soon as I start modulating the current with music, sparks appear. Disappointed =(
I'll try to figure out, what's going wrong. I suspect the sparking may be provoked by discharges around insulation of high-voltage wires that go to the amplifier.
video
DeepSOIC • 10/14/2015 at 23:16 • 0 comments

Probably a boring video. Just playing with it by varying voltage. Don't even have a voltmeter set up.
The LED behind the blower is connected in series with the blower, to serve as a simple current sensor. Also there is a 200k resistor in series, to make sparks less loud and annoying. Though, this causes arcs instead of sparks. This may cause damage by melting plastic, but so far so good.
The blower is quite noiseless. You should be able to notice clock ticking if you set the volume high.
On thermal camera
DeepSOIC • 10/14/2015 at 22:32 • 0 comments

It didn't melt the plastic, great. But I was curious to know, how much does it actually heat up. So I took my thermal imager, fired the blower up, and... NOTHING! I barely can see the corona wires on the thermal imager. What tha?! How can that be possible?
I can't say I'm disappointed. In fact, it is much better than I could imagine! COLD PLASMA =)))
mistakes...
DeepSOIC • 10/12/2015 at 21:14 • 0 comments

model design went through two iterations already. First one was printed, fails noted, design modified and changed parts reprinted.
The problems were:
* mating system between basket and backplate was not working (too weak, and wasn't fitting, so I broke it attempting to put them together)
* rib on the frame was too small. If I put the mesh in between, the ribs won't cover the basket.
See that ring of plastic that detached off the basket? FAIL.