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cathalgarvey

RotaVac - A Rotary Vacuum Pump

by cathalgarvey Jan 3, 2010
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How about spinning it in the opposite direction. That should force air out the nozzle creating a vacuum around the device. Put it all in a large tube with a narrow opening at the top and see how that works.

We built this part at http://hacklab.tohacklab.to, hoping to be able to achieve a little vacuum power. It printed great, looks super cool. We tried rotating it at low speed using a drill, but didn't feel anything. We then removed the gear box from a standard DC motor, to get a 9000 RPM motor. Hooked up to this device, the device spins awesome, vibrating a lot if things are not perfectly centered. We used some bamboo fitted inside a bearing, inserted in the center hole. Holding the bamboo provides stability during operation (that's why bamboo is superior to plastic tubing!) But no pressure/suction is obvious. We did a smoke test using solder, and showed that there is a tiny amount of suction into the bamboo - the smoke is sucked in from up to about an inch away. My estimate of the suction power is about 0.1 PSI.

We considered printing multiple devices and stacking them up for more performance, but with performance levels this low we're too far from our desired application for even that to be practical :(

Anyway, thanks for the design, we had fun prototyping this idea tonight.

Wow, cool! I never imagined someone would get it working, I was pretty disappointed when I could never get it going myself. I don't know why it didn't work for me exactly, perhaps less is more when it comes to impeller ribs.

You guys rock! If ye know any way to improve it, please do. I'd love to see a working air pump/vacuum pump that can be printed and embedded, there's so much potential if we can get something like that working. :)

You just can't stop spinning stuff!

Give me RPMs or Give me Death!
Seriously though, rotary designs are probably the lowest-hanging-fruit in the functional Makerbot arsenal; if you want something to do work, and you want it to be tough and easy to print, it's best to have a single-piece design. The only practical way to make that do work is to spin it!

So V
íve le spun designs for now, I can make them more complicated later when I have proof of concept! For now, I demand more stuff-that-does-stuff! :)

hey keep them coming excellent job!!

We'll see how well it works when I get it printed! :)

Did you take an analytical approach to designing this?

I'm really interested in seeing the performance of a printed impeller.
Also another option would be to order the impeller as a replacement spare part.
http://www.dewaltservicenet.com/http://www.dewaltservicenet.co...

Define "Analytical"? I had a bit of advice from an Engineer somewhat familiar with pumps. There wasn't any math involved, because I don't know the math necessary. I figured I'd print it and see! :)

Analytical as opposed to experimental, that way you could compare the theoretically calculated performance with the actual performance. I'm wondering how much of an issue the textured surface of the 3D printed plastic would be.

Well, it's my hope that the vertical ribbing created by Makerbot/Reprap's deposition of filament will create the air equivalent of sharkskin ribbing:
http://is.gd/5LZtxhttp://is.gd/5LZtx

Sharkskin ribs are tiny tiny, but aerodynamic features are often coarser than hydrodynamic feature by orders of magnitude.

I reckon it'll work, anyway, but I'm not too concerned about efficiency. As long as it can generate enough aspiration force to suction stuff in the lab it'll suit my needs! :)

Although if it works really well, we could make a homebrew printable robot vacuum cleaner..