Vacuum source

[Paul Jones]

After discussions around aquarium pumps I was thinking last night, what about a car tyre pump? They are cheap and shouldn’t be too hard to add a pressure fitting to the inlet, and a small tank of some sort (perhaps an old air cylinder from ebay?) could be used for storage of the vacuum so the pump only needs to run every few minutes. 40+ psi should be very good at holding components stable no matter how fast the head moves!

 

Thoughts??

 

 

Paul.

[Ami]

Why not just simple compressor and venturi valve?

Car pump can not run for a long time, check the spec.
You can put the entire car pump into a bin, and make vacuum out of it.
It's like degassing chamber for silicone rubber.

But I don't have space on my desk for that!

[Karl Lew]

Because my wife would kill me if I brought the compressor in the house. The damn thing is loud. I suppose a long compressor hose could keep it in the garage but the venturi hissing would really freak out the cats.

[Ami]

Well you gotta choose, cat or PnP. ;-)

For me it's a pending-problem. Sparkfun is the default solution because it works, and it's not expensive even if I have to throw it away later.
The machine is not in living area so there's no compatibility issue with cat and wife. But still it's giving me headache.

I am thinking of double or tripple or quadruple computer fans to make a turbine. Would that work?
Or find / make some kind of blower with 3D printer and DC motor.
Then either use venturi or by turning it on and off.
But the hissing will still be there,

as I said, you gotta choose: Cat or PnP ;-)

Btw, if you use bigger stepper motor it will make a noise as well!!
Mine is a 300mA motor, so it's making noise like an inkjet printer. (and it's slow).

[Karl Lew]

Meow.

I am not sure about the fan approach? Seems like high cfm but very low pressure differential? The aquarium pump has that bellow design with the the little silicone valve dojobbers. So when the electromagnet spazzes periodically, it generates a pressure spike that makes it through the "diode" valve. I cant quite picture how the fans might work since they dont have the shock wave that gives you the headache.

[Ami]

Haha yes, poor sylvester.


I'm thinking of airplane turbine idea, so a stack of fans (rotating in different directions?), and a funnel behind it.
The smaller end pipe will have higher air speed than the fan blades.
So you can keep the air flow continuously, even push it outside the window if you will, and control the suction with a venturi valve .
It's just an idea, basically replacing the compressor airflow with a turbine.

I'm not sure if it will work, but if you have to choose against sylvester....

But hey! Tweety always win!

[Ami]

Happy new year everybody,

Before I run, I'd just like to throw an idea of replacing sparkfun pump with PC water cooler pump such as http://www.swiftech.com/mcp350.aspx
It's supposed to be quiet (26 dBA), and generate 44 inch-hg with water, so even if it looses some power with air, it should still be strong enough.
For comparison sparkfun spec only says 16 inch-hg , and it's way to strong for smt-pickup needs.

Inside the pump there's a turbine/centrifugal pump like that of a vacuum cleaner.
The way I think about it, it's either noisy diaphragm pump like sparkfun, or gear-pump (less noisy, but still)
or a turbine system. As I was browsing, I ended up with this watercooling pump.
Since it's for PC cooling, it's supposed to be silent,


I think it might work for our needs.
I wonder if someone have one of these lying around and might want to try it as vacuum source for smt pickup.

gtg,

[DAniel Dumitru]

Happy new year !!!

Good to mention this option Ami !
However at this price we (85$) we can buy a dispenser which is in fact
professional solution for our problem.
It's needed indeed an air compressor , but I bet that all the PNP
machines requires air pressure.

Kind REgards,
Daniel

[Ami]

Oh yes! I didn't mean that model in particular,
I mean to explore the centrifugal/turbine solution.
I have raft inflator pump which works with this system, and I can report that it works, but it's mighty noisy!!!

I'm thinking the PC cooling or aquarium applications because they're supposed to be silent, they might have something hidden to be found.
And since their pipes are quite small (<10mm) the pressure loss without liquid might still be acceptable.
There are many water-pump with brushless DC motor that might work.

WARNING: some pc-cooling pump are not supposed to run without liquid, so test at your own risk!! you risk your 85 bucks! 

[Ami]

Otherwise there's this gear-type pump: http://www.produktinfo.conrad.com/datenblaetter/200000-224999/207894-an-01-ml-KRAFTSTOFFGETRIEBEPUMPE_12V_de_en_fr_nl.pdf
It looks similar to the diaphragm pump (sparkfun) but it's fundamentally different system: it's using two gears to "carry" liquid from one chamber to another.
So since there's no vibrating part, this pump SHOULD be slightly less noisy than the diaphragm system.

Pressure drop is also possible since air is not liquid, but it should work for our purpose (60cm water pressure).
A few drop of oil may be necessary to lubricate the gears and prevent air leaks.
With gear compressor, as soon as the motor stops the pressure will quickly drop as well (unlike diaphragm), which in our case is much better, so the needle can lift up asap.

It's not whisper silent, but I think it should be acceptable to sylvester.

[DAniel Dumitru]

Going on this ideea (having a cheap replacement for vacuum source) I would try one of those (Are replacement pumps for solder stations) :











BR
Daniel

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[Hedley Davidson]

I am testing small rc ( radio Control ) motor with ducted fan - normally these run very high rpm but finishing circuit to drive pwm output from pic controller for speed control . After calibration the display will give suction pressure readout . Will include inline switch to reverse airflow from other side of fan for " blow off " .

[cf]

I always thought the best solution for quiet vaccum was a diaphragm pump. I see a lot of differen suggestions, is there a reason a purpose build vacuum source such as http://www.perfectgoodhelper.com/goods.php?id=131 couldn't be used ?

Since I am only in the planning stage yet maybe there are practical limitations using that type of pump that I haven't seen yet.

Carl

[Karl Lew]

Ami, Happy New Year!
Thanks for thinking about the lady cats. I am actually the only guy in the house. Just for you I shall start calling them each Sylvester. 8)

I still havent tested my aquarium pump, since I am working on vacuum switch using Sparkfuns cute little 5v solenoid. The idea is that the pump will always be on quietly sucking room air. The activated solenoid plugs the airhole at the needle, which should (?) cause a pretty quick vacuum to form. I am counting on the continously moving air mass in the tubing to make the transition to vacuum quicker. I hope I can do better than the awful Chinese aquarium pump some of you tried. If not, I may go Sparkfun pump with lots of soundproofing. Have you tried putting pillows around that thing?

[Ami]

Karl,
You know Sylvester and Tweety from Disney don't you? Tweety always win! ;-)
Now here's how to get tweety err... pnp machine back in the living room: mission: whisper-quiet operation!!!

- Diaphragm pump: Noisy!
Sparkfun and the other pumps that Daniel posted are all diaphragm pumps I think.


- Aquarium AIR pump.
I think there's problem of low pressure; may need to find a really big one.

- PC cooling pump / Aquarium water pump.
Check the EK-DCP 2.2 12V (photo above).
Now These are really quiet! NOISE: 17 DB!!! Sylvester can sleep on it!
I thik it's just a DC motor inside, and a turbine.

It can pump 2.2 m of water, so the pressure should be around 6 inch-hg. (sparkfun = 16).
It should be enough for PnP, otherwise there's a bigger model with double the pressure.

IF dry operation should fail:
Put two small water reservoir one on top of the other.
Connect the pump to "pump" water from lower to upper water reservoir.
The air chamber in the lower reservoir has the negative/vacuum pressure.
Connect our pick-up pipe to this lower air chamber, and voila!! Done!

Better yet! As soon as the motor stop, the water from upper reservoir will flow back to the lower one, and "blow" air through the needle.
So as soon as the pick up needle put the part on the board it can lift the head without waiting.
(The wait time with sparkfun's is also slowing down the pnp cycle)
If the needle is air-tight with the part, there should be hardly any water flowing.

I wonder if this solution will work.
I think it will!

[Paul Kelly]

Most commercial machines just use a venturi.  You’re already using a reasonable amount of air for clamps, stops, pushups, feeders etc...

 

PK

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[Karl Lew]

Tweety always wins. And Sylvester never gives up. My Heroes!
I also now have scientific proof that the lady cats will happily come get their food when "Sylvester!" is called.
I guess I should have expected as much since they also respond to "LadyFurryFatAssesComeEat!"

Ami. Your water pump design is delightful. I doubt it will work as is for air because the mediums are so different, but your second idea might, since it is basically a liquid diaphragm pump if the pump is reversible. We could even put goldfish in it for the cats. Please do not kill yourself. Electronics and water are not good mixers.

If all else fails I will give my cats earplugs for the hissing venturi.
--Karl

[Ami]

Karl,

The water-piston design needs to be tested.
I was just being creative after new year, to check if there're still enough neurons left.

I see the water as vacuum piston.
So as the pump pushes water to the upper chamber, the lower chamber becomes bigger / has lower pressure.
This is the source of vacuum, so the water-piston will move up and down as the PnP runs.

However, the reservoir must be big enough to account for air leakages, THAT's the problem!!

It may work for 0603 or even DPAK, but comes SOD-80C, the air leakage volume will be bigger than the reservoir!.
I doubt that computer cooling reservoir might be enough (400 ml?)
As soon as the lower reservoir gets empty, the pump will start pumping air / bubbling into the upper chamber.
There goes the air leakage, vacuum pressure will still be there, as the pump continues pumping mixture of water and air,
but I am not sure if it will be enough to keep the part on the needle.
This needs to be verified!!

If someone has the pump at hand, and would like to test it and give us feedback it would be interesting to know:
How long can it hold an 0603? how long can it hold SOD-80C?
(For testing you can replace the upper reservoir with a bucket.)

So, otherwise, Karl, you might want to start browsing for cat-earplugs.
At least sparkfun pump works.

[Karl Lew]

Ami, yes I do love Sparkfun pump specs of 32psi and 12-15LPM. I may need to kill it with a pillow or two, but....

By the way, I never heard of a SOD80C. What on earth are you guys building that needs such wild parts?

[Ami]

SOD80C : diodes, zeners in switching supplies or others.

[Ami]

SOD-80C and larger chips will not work with low pressure vacuum pick-up manual tools.
The PnP head moves much faster than human hand, and more abruptly.

But here's the DEFINITIVE SOLUTION for sylvester and family:
http://shop.wiltec.info/product_info.php/info/p3950_Airbrush-Mini-Compressor-and-Vacuum-pump-in-one-device--AS20W.html
Or look for other silent airbrush compressor, there should be similar product near you.

It's a mini- airbrush compressor and vacuum, with 40dB noise level!!
Vacuum pressure is quite high: 24 inch Hg.
I would add a valve to avoid turning it on and off too many times, the piston may not like that.

[Daniel]

Well, personally I think that this thread looks like a brainstorm to reinvent the wheel.

But since I got into this, please look at my proposal :
http://dx.com/p/usb-powered-mini-turbo-vacuum-cleaner-with-brush-and-illumination-led-3551

http://www.youtube.com/watch?v=AGyUQc3iljc

in fact this would have so little mass that it could be mounted directly on Z axis !

On same alignment we have baby nose vacuum :
http://www.shopmania.ro/q-aspirator-nazal   (sorry it's on romanian)

Daniel

[Ami]

Wow, good finding.

I wonder if the pressure is enough.
You know, reinventing the wheel is not so bad, in the other thread we're making replacement for gravity.

;-)

[Karl Lew]

Ami,

Vielen Dank! Das ist gut. Sylvester muss Deutsch sein.

8) Karl

[Karl Lew]

Daniel, oh.

Man, am I dumb. Oh so dumb. My wife would never object to my using the vacuum cleaner. And the cats are ok also. And we have a Miele. It sucks plenty good and is plenty quiet.

Crap. That is the BEST solution of all.

Thank you! Great idea. Problem solved.

"Honey? I am going to vacuum a bit. Hope that is OK."

-Karl

[Daniel Dumitru]

Karl - I do have objections to this solution.

A house vacuum cleaner it's far to big !!! we should use something else.

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[Ami]

Oh! That's not what I mean, I'm sorry to have picked the wrong word !

Most certainly for Sylvester, that the joke should not continue in this direction,
it's true that this "definitive solution" has a nice gas err.... air compression chambre.

But seriously,
The particularity for this model is that it works as vacuum as well as compressor.
And it's not so noisy.

The other "definitive solution" I'm thinking of is to plunge the sparkfun in oil, as to make it like refrigerator compressor.

Otherwise Daniel's USB vacuum is a nice cheap candidate.
If anybody have one, can you just test it for pick and place?

[Karl Lew]

Daniel,

There is a certain absurd rightness to the house vacuum cleaner idea. My vacuum design is "always on with air valve". As you mention, vacuum cleaners are too big and I think they are also not designed for long production duty cycles. However, they are commonly available, which is ideal for me since I am going for $500 PnP. This way I can design cheap system that is upgradable to whatever you guys come up with. E.g., Sparkfun in oil.

8) Karl

[Karl Lew]

I have data. Just got my vacuum gauge.

Miele vacuum cleaner 2.5-2.7 psi.
ShopVac 2.1psi.
Both can sustain that level of vacuum for multiple vacuum pickups.

That is on the low end of acceptable for PnP, but not unreasonable for starter PnP, and $75 will get you a much better vacuum pump. Folks can start with vacuum cleaner they already have and then buy up to better performance. No need to hassle with reversing aquarium pump.

Cats did not run when vacuum was turned on. Wife smiled.

This is promising.

[Jason von Nieda]

This seems like a fun experiment, but I can't imagine it would be a good idea to actually use it. I don't think vacuum cleaners are meant to be used for extended lengths of time, and certainly not sucking vacuum against either a tiny orifice or a closed solenoid. I'd expect motor burn out pretty quickly.

Jason

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[DAniel Dumitru]

Vaccum cleaner motors are relying on air flow to cool themself.
If you will close the aspiration duct at all you will hear that motor
RPM will increase fast to infinite.
In this application we may leave a small section always open.

[Karl Lew]

Yes. You are absolutely correct. Vacuum cleaners are air cooled. That is why I gave two numbers for the Miele. The higher 2.7 number is full blockage and burnout potential. The surprising result was the second 2.5 number which was achieved by having an open 1/4" OD air hose in tandem with the pressure gauge which was closed since it was measuring the vacuum. The CFM for the vacuum cleaner is so high that a partially open hose can cool the vacuum cleaner but still generate some useful vacuum. It probably wont be strong enough to do glass enclosed cylinders smds that Ami mentioned, but It should pick up many parts.

I think we need to have a spectrum of pumps. Low end can be vacuum cleaner for getting started with a low budget. Next step up can be:
http://www.amazon.com/Robinair-15115-VacuMaster-Single-Stage/dp/B005CO9FDW/ref=sr_1_6?ie=UTF8&qid=1358007133&sr=8-6&keywords=vacuum+pump
Then the high end can be venturi solenoid driven by air compressor. I have an air compressor but the damn thing is too loud. The neighbors would kill me at 11pm if I turned it on. Vaccuum cleaners are quieter and I can run my machine at night. I can then switch to high vacuum as needed if I do PnP during day.

On a tangential note, one thing I like about separate pumps is that the power supply requirements are also separate. I dont need to worry about powering the pump, just the steppers.

[Karl Lew]

I've tried to summarize all the great comments in this thread along with other research into a single page that hopefully summarizes what we've discussed in brief. I'd be grateful if you all would review it and let me know what I missed or misrepresented.

https://sites.google.com/a/firepick.org/www/design/vacuum

And if the information should be posted elsewhere for openpnp'ers, please feel free to copy as you wish, it's all CCSA. The FirePick site is just my attempt to provide complete BOM and assembly instructions for one possible OpenPnP machine.

Thanks,

Karl 

[Ami]

Well, The only reason we have this lengthy discussion was Sylvester.
At least Sparkfun works as far as PnP is concerned, and it's not expensive.
I think it's worth noting, it's not a blocking issue.

I haven't had the time to try it, but I'm thinking of putting sparkfun in a (don't laugh) baloon, or plastic bag,
Seal it tight with air tubes and cables out, and then plunge the whole thing in oil-filled container.
The exit (blow) air can be used to cool the motor as well,
That would certainly reduce the noise.

BTW, nice name you got for your machine: Firepick Florentine.
I haven't come up with a name for mine, not very creative with naming things.
Perhaps I should call it Sylvester.

[Karl Lew]

Ami, I hear they are mineral oil cooling servers now. Works great. That you thought to extend that approach to noise abatement is brilliant. And thank you for putting the pump in the bag instead of Sylvester. She is grateful.

Miaow,
Karl

[Hedley Davidson]

Many years ago we were vacuum bagging high performance glider wings . Needed reliable , quiet low cost and long running vacuum pump. Best bang for the buck were vacuum pumps from ATM machines we were picking these up for us$ 30 ea at the time from ATM ( autoteller refurbishes ) . Perhaps worth a look .

[Hedley Davidson]

http://www.atmgear.com/009-0009159.html . These were the ncr units we were using which run all day every day in the ATM,s

[Karl Lew]

Amazing that ATMs have vacuum pumps. They must be quiet, too.
Here is a link to specs of a dc charles austen pump that maybe is that one?
http://www.charlesausten.com/Files/charlesaustenpumps/pdfs/88559.pdf
That is one good high vacuum 12v 0.7A stealth sucker.

[Jason von Nieda]

The one on the left in the datasheet looks very similar to the SparkFun one. https://www.sparkfun.com/products/10398

Maybe the SparkFun one is new old ATM stock.

Jason

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[Karl Lew]

Sparkfun pump is Airpon. Chinese. Maybe Chinese ATMs are loud? Or they put it in a bag of mineral oil?

[Jason von Nieda]

I think you'd be hard pressed to call the SparkFun pump loud. I just hooked mine up, set it on a small foam block (so it doesn't transmit vibration to my desk) and turned it on and you can still speak at a perfectly normal voice and be heard fine. Then, for fun, I put it in a small cardboard box and it's nearly silent. To keep with the animal analogies... my dog, who was laying right next to me, didn't even look up :)

I'd say put it in a small box, maybe with some cheap craft foam as a buffer and you'd be set.

Jason

On Mon, Jan 14, 2013 at 10:53 PM, Karl Lew <ka...@firepick.org> wrote:

Sparkfun pump is Airpon. Chinese. Maybe Chinese ATMs are loud? Or they put it in a bag of mineral oil?

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[Ami]

I agree with Jason,

it's not loud, just annoying after a long run. It's not a blocking issue.
Otherwise dip it olive-oil with some oregano and piment-rouge will silent it for good ;-).

[Karl Lew]

I bet yor dog would look up if I brought my cat over. 8)

I might use an external pump such as the Robinair. I am a little worried about power consumption with 9 steppers. If steppers are .33A@12V I would be fine with Sparkfun pump. If more I would be toast. Thanks for both recipes for sound mitigation.