Laser cutter Air assist pump options

[Max Nippard]

Does anyone have experience with airbrush compressor or similar things?
How loud are they and will they die if run continuously?

[Andrew]

What kind of air flow are you looking for?

 

I just picked up a dual-outlet fishtank air pump at a local aquarium shop for $29.  One side has been hacked to provide vacuum (well "suck" anyway) for use as a vacuum pickup.

 

They are pretty quiet (50hz hum) and are find for continuous ops.

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[Max Nippard]

Air flow between 30 and 100 litres per minute is what most people use.
I think the one we have is lower than that though.
Most people buy the big air pumps made for running many fish tanks while making a hell of a racket. Like this one http://www.guppysaquariumproducts.com.au/air-pumps/electromagnetic-piston-pump/hailea-aco-208-air-compressor/prod_3403.html

[Andrew]

The fishtank pumps tend to be diaphram types because they need some amount of pressure to work against a head of water.  This makes them noisier.

 

A fan-type blower will give higher volumes but won't handle backpressure/restrictions.  Generally, it should be quieter.

 

Maybe something like this: http://www.aliexpress.com/item/NMB-BL4447-04W-B49-11028-12V-2-0A-Blower-Server-Case-Cpu-Cooling-Fan-Free-shipping/856910646.html

or http://www.aliexpress.com/item/The-Delta-turbine-centrifugal-fan-wind-capacity-exhaust-blower-9733-12V-2-94A-BFB1012EH-cooling-fan/935493113.html

 

Jaycar has a smaller version, but I don't think it would be up to snuff.  http://www.jaycar.com.au/productView.asp?ID=YX2532

[Kris]

Are you wanting it for airbrushing or vacuum pick up?
There is a vacuum pick up pump in the space's solder suite. It's surprisingly quiet.

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[Andrew]

Kris - I thought the discussion was regarding the laser cutter (per subject line).

 

If the intent was airbrushing, then I happily withdraw my comments.

[Kris]

Ah yes sorry. Been a long day
Please ignore

[Max Nippard]

There is a fair amount of back pressure as the air must travel through at least two metres of aquarium air line to the lens carriage.

[kaindub]

Max
'a fair amount of pressure"
if you can blow into the tube and get air out the other end, the backpressure is going to be much less than 3psi (sorry for th the old units)
But those little fish pumps are going to struggle to put out 35 litres per minute at even 1 or 2 psi

Quick alculation
lets say 60 litres per minute
Connected to a 2 pole motor running on 50 hz (3000rpm)
Need a cylinder of 20 cc assuming 100% volume filling on intake stroke and complete exhaustion on exhaust stroke
Thats unilkely
But what you need is a pump the size of your small whipper snipper (33cc)
Thats for a positive displacement pump

Robert

[Max Nippard]

Yep. I know.
The question is which whipper snipper sized pump is suitable at a reasonable price?

[Andrew]

Does the space not have a "full size" air compressor with tank?  If so, maybe that is the way to go and to rig up an air distribution system for multiple users.

 

From: sydney-h...@googlegroups.com [mailto:sydney-h...@googlegroups.com] On Behalf Of Max Nippard

Sent: Thursday, 29 August 2013 10:45 PM
To: Robodino List

[Ada Lim]

On Thu, Aug 29, 2013 at 10:24 PM, kaindub <bud...@ozemail.com.au> wrote:
> if you can blow into the tube and get air out the other end, the
> backpressure is going to be much less than 3psi (sorry for th the old units)

back pressure is a function of flow.

> But those little fish pumps are going to struggle to put out 35 litres per
> minute at even 1 or 2 psi

it's a good thing it only requires 0.1psi to move that much air, then, eh?

science. it works, bitches.

(workings at http://goo.gl/mDwqYa. viscosity of air obtained from
http://www.wolframalpha.com/input/?i=viscosity+of+air+at+room+temperature)

[Ada Lim]

On Fri, Aug 30, 2013 at 12:10 AM, Ada Lim <a...@panda2.net> wrote:
> science. it works, bitches.
>
> (workings at http://goo.gl/mDwqYa. viscosity of air obtained from
> http://www.wolframalpha.com/input/?i=viscosity+of+air+at+room+temperature)

(of note is that I assumed 6mm ID tubing - 5mm tubing roughly doubles
the backpressure.)

now I want to just use an overvolted camping mattress inflator - the
specs are right, but the duty cycle rating is probably off. computer
impeller fans top out at a backpressure of about 1 mmHg, so are mostly
out.

[Max Nippard]

No,  we don't have a compressor.
Some laser builders use a regulator with there workshops air supply. Not many though, it might be the low cost of the large aquarium pumps is lower than the compressed air fittings.

[Jason Ball]

Pull a compressor from an old fridge, just be careful when you vent the gas.  They work well as a budget air compressor.

J.

[Kris]

Aaaaand now in the correct thread. Sorry

would the compressor from my little water cooler work?

[Max Nippard]

The one you dropped at the space uses a peltier instead of compressor and gas.

I would guess the output rate from a frige compressor will be a bit low for best results anyway.

[Kris]

Oooo
Ok, I'll come get it tomorrow

[Jason Ball]

Depends on what it came out of.   I have previously used a compressor from a car air-conditioner combined with a washing machine motor to pump up tyres on a tractor.  As they say necessity is the mother of invention.    

Given the costs of basic air compressors these days it may not be worth the effort, I've seen products from bunnings etc in the $200 range.  A regulator to drop the air pressure down to a level where it won't leave bits of laser tube embedded in the case/ceiling/walls/people would probably cost more than that.

Cheers

J

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[Kris]

You know how we aren't supposed to leave the laser machine running unattended? What about a bicycle powered fan to enforce that rule ;-)

[Patrick Barnes]

Um, so if you're not there pedalling it catches fire?

Excellent!

-Patrick

[Jeremy Nelson]

As a note- I'd be happy to help construct an enclosure to quieten down any noisy pumps ala:

http://www.instructables.com/id/Dust-Sniper-quiet-extractor-system/

It may not work quite as well for a compressor since it may require more ventilation, but...

Jeremy.

[Iain Chalmers]

I'd guess a "squirrel cage" type impeller fan is the right answer - a car's interior fan or a vacuum cleaner.

Some more "science, bitches".

From Ada's numbers:

3mm radius pipe

0.5L/s flow rate

566Pa pressure difference

Power = force * speed

force = 566 N/m^2 * (3.14 * .003 ^ 2) M^2 ~= 16 * 10^-3 mN

speed = (0.5 / 1000 M^3) / (3.14 * .003 ^ 2) M^2 ~= 17 m/s

power ~= 0.3W

Even allowing for an order of magnitude of inefficiency, if you could get some reasonably airflow-equivalent of impedance matching, we're looking for something much closer to a computer cooling fan than an air compressor or a vacuum cleaner (I'm pretty sure my vacuum cleaner is labelled "1400W"). Has anyone tried a typical 120mm pc cooling fan? Something like this: http://www.jaycar.com.au/productView.asp?ID=YX2584 claims to pump 60CFM at 2.6W - that's one cubic fot per second, or about 20 times more than the desired 0.5L/s. Figure 3 on this page: http://www.nmbtc.com/fans/white-papers/dc-brushless-cooling-behavior.html seem to suggest 566Pa which is about .17inches of mercury, might only knock 15% off the flow rate - which stll leaves us with an order of magnitude of margin... (Unless I've done my usual "dropped a few orders of magnitude in the estimates/calculations along the way).

I'm pretty sure a vacuum cleaner/air-compressor and even an air mattress inflator are _way_ to big for this. 

big

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[Ada Lim]

Mercury isn't water.   Don't drink it.

[Iain Chalmers]

On Mon, Sep 2, 2013 at 1:20 PM, Ada Lim <a...@panda2.net> wrote:

Mercury isn't water.   Don't drink it.

But isn't it supposed to help with both constipation and syphilis?

Mad-as-a-hatter-Big

[Ada Lim]

On Mon, Sep 2, 2013 at 7:50 PM, Iain Chalmers
<big...@mightymedia.com.au> wrote:
> On Mon, Sep 2, 2013 at 1:20 PM, Ada Lim <a...@panda2.net> wrote:
>>
>> Mercury isn't water. Don't drink it.
>
> But isn't it supposed to help with both constipation and syphilis?

Not as much as penicillin does.

(the graph tops out at 0.8 in H2O which is about 1.5mmHg. some people
might see this as an argument for SI units.)

[Max Nippard]

I have ordered a Hailea HAP-60

Hailea HAP Series High Pressure Pond Air Pump

• Hailea HAP60
• 45W
• 220-240V 50Hz Australia Plug
• 60L/min max.
• 0.035MPa max
• 40dB
• 203*165*153mm
• Plastic Manifolds included to suit 4-8mm air tube.

Features:

• High Pressure, Large volume Output
• Oil-Free Output, no pollution to water
• Low noise-Multi-level Noise-damping Design
• Electromagnetic Diaphragm, easy to replace.
• Energy Efficient

Application:

• Fish Pond & Garden Water Aeration
• Oxygen Supplier for the aerobic systems, septic tanks and sewage treatment.
• Aeration for air beds
• Hot Tubs or Pools
• Metal Soldering

[Max Nippard]

What should i write to the eBay seller of the FAKE Hailea air pump i just received from Queensland?

First draft is:

Hey,  this pump seems not to be a Hailea brand one as per your ebay listing. Changing brand name in the instructions with a biro? Cutting the top and bottom off the sticker on the pump? Is it C tick approved?

[ivanjh]

Well... the first question is: What are you trying to achieve?

Refund? More suitable price? Hilarity?

[Max Nippard]

I haven't looked inside yet to see if it's held together with string and chewing gum but option B or C looks good.

[ivanjh]

Dear XYZ, the unit I received is clearly not a genuine ABC pump as the listing indicated.

For a non-genuine unit like this, I would be willing to pay $N for. If you issue me a $M refund, we'll complete this transaction for the non-genuine unit, otherwise we'll have to cancel as the item isn't as described, while I dance naked on top of a harpsichord singing "I'd only pay that for a genuine Hailea. Oh, Pumpy Pumpy Pumpy!".

[Max Nippard]

Thanks Ivan, but I was impatient and sent a question to the seller 5 minutes before seeing your email.
Just an opening note asking if it will be compatible with Hailea parts and has a c tick.