Vacuum

[Miroslav Pejic]

Hi folks,
Is it possible to use refrigerator compressor as vacuum pump?
I'll appreciate any suggestion if some one has experience to share.
Miroslav

[Richard Spelling]

http://www.surpluscenter.com/item.asp?item=4-1817&catname=air

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[Johannes Taelman]

I'll do my first experiments with AOYUE 932,
as an alternative I'm looking at this one :
https://www.sparkfun.com/products/10398?

Richard, your choice looks really nice, unfortunately I'm in the EU,
which means expensive shipping, duties, and the wrong voltage on top.
I'm not aware of similar surplus stores in the EU, and also google
seems to have a strong USA bias when looking for industrial stuff.

Johannes

[Jason von Nieda]

I have that SparkFun pump. It does move a decent bit of air. I've done some test pickups with it using a bit of 16 gauge hypo tubing and some 0805 parts and they seemed to stick pretty well, but I have not yet tried it under real load.

Jason

[Drmn4ea]

You can! It might be overkill for PnP. I did a writeup on the process a while ago, using one for high-voltage plasma experimentation:

http://tim.cexx.org/?p=527 (search "compressor")
http://www.youtube.com/watch?v=VkK4hjBQ6k8
http://www.youtube.com/watch?v=ShAN0LLOV

I found that the one I salvaged could pump down to ~ 20 Torr (rough estimate). Beware of course products that use these (refrigerator, etc.) are a closed-loop system consisting of typically environmentally-noxious refrigerant gases mixed with oil under pressure, so don't cut open one that still has refrigerant and vent it into the air. (Besides the bad karma, probably illegal in many countries.) If the refrigerant has already leaked / been recovered you're good to go, just beware of the oil. As a vacuum pump you'll no longer have the cooled oil circulating back to the inlet as coolant, so it will probably not last as long in this role as a home refrigerator. But it does pull a solid vacuum at reasonably high throughput (MUCH more than e.g. a fishpump) and fairly quietly.

Tim

[Ami]

I'm using sparkfun as well,

It works alright,  but after a while it gives me headache.
It's not loud, just that it's not very pleasant after a long while.
I guess I need to correctly add a suspension to reduce the noise.
You can hear the sweet sound of the compressor in : http://www.youtube.com/watch?v=fnlrRPhA5-s
Imagine if you have a short run to do.

[Karl Lew]

I'm planning on using an aquarium pump, with the valve reversed. I bought the ActiveAQUA  AAPA15L, which moves 15L/minute at >2.3psi with <45dB. 

[Ami]

I have chinese smt-pickup which was an aquarium pump, it wasn't strong enough for bigger parts.
Suction force also reduce misalignment, as the head moves up, the part may rotate slightly.
Stronger pump reduces this problem.

That's why I changed it to sparkfun pump.
My mistake with the noise was that I fix the pump to the aluminium frame of the machine, which makes it vibrate all together against the table.
The pump is VERY strong in that sense.

[Karl Lew]

Interesting! I remember that video of the chinese vacuum pen. I was afraid of the weakness you mention and so bought a bigger aquarium pump. I listened to the sparkfun pump and it was loud. the aquarium pump is quiter. I dont want my wife to kill me if it's too loud because my machine is in the living room. Were you using the larger suction cups for the larger pieces when the chinese pen failed?

[Richard Spelling]

my chinese pen failed too.

I use the surplus center vacuum pump on Zippy, 16ga needle, without any
suction cups at all...

I pick up SOIC16 and DPAK parts with it all the time.

I highly recommend it. I bought three just to have extras. Gonna use one
for the air assist pump for the laser cutter.

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[Ami]

Chinese vacuum is ok for hand-picking, but not with the machine.

After a long run it smells hot/burnt-rubber all over the room. (Machine does not need coffee break)

The other problem is part rotating or moves when the head is stopping or changing direction.
The faster the head moves the stronger the vacuum must be.
I use the biggest needle I can for 0603 (1.2 mm) and it can still do DPAK (with some mis-alignment)
changing the needle is a hassle.


Richard: How's that Surplus Center pump compared to sparkfun in term of noise?