Help with an idea for air-bearing pump

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Paul Ebert

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Joined 2003
#1
I may need to find an alternative compressed air source for the air-bearing in my DIY tonearm as my current compressor is starting to make an odd noise (and it's only 3 months old!).

My requirements are for 0.012 scfm at about 40 psi.

When I was looking for my current compressor, I looked all over the place for an affordable and quiet pump. I also wanted it to be oilless, so I didn't have to buy filters all of the time. What I found seemed pretty much the only game in town besides going with compressed air, which would have been costly.

One idea I had, but didn't pursue, was using a refrigerator or freezer compressor. Not the typical application for such, but I wonder if it would work. Does anyone know anything about them? In particular, what their output (volume and pressure) is?

Thanks.

Paul Ebert
 
#2
A fridge or freezer compressor might do the trick. But they are not exactly oil-less. Also quite some fluctuations on the output (pulsed air) so you would need a buffer. And they can get quite hot when running like you intend. No idea about volume or pressure delivery.

Take a look at artist supply shops for them. They are used for airbrush work, and come then complete with filter and buffer tank.
 
#3
Havoc said:
A fridge or freezer compressor might do the trick. But they are not exactly oil-less. Also quite some fluctuations on the output (pulsed air) so you would need a buffer. And they can get quite hot when running like you intend. No idea about volume or pressure delivery.

Take a look at artist supply shops for them. They are used for airbrush work, and come then complete with filter and buffer tank.
Click to expand...


Thanks for the reply. So, there is some sort of oil or lubrication in the coolant gas? I guess that would make sense. Given that, the only benefit I can see is, maybe, cost.

I've been looking at airbrush compressors. Suitable ones tend to be upwards of $500 or so. Another option is compressors for dental work. These are very quiet and reliable, but are $800 and up. They all use oil. Perhaps I should ask my (few) dentist friends to keep an eye open for a used one for me.

Pulsed air is not a problem as I already have a buffer tank and regulator/filter.

Thanks, again.
 
#5
slowmotion said:
Hi ,

I've been using an aquarium pump, no oil

cheers
Click to expand...


This would be great if it met my requirements for pressure (40 psi) and flow (0.012 scfm). Do you happen to know these specifications for your pump? My impression has been that aquarium pumps don't put out much pressure. If yours is suitable, could you please let me know its make and model number? If the flow was too low, I believe I could use multiple pumps to make up for it.

Thanks!

Paul
 
#6
Paul Ebert said:



This would be great if it met my requirements for pressure (40 psi) and flow (0.012 scfm). Do you happen to know these specifications for your pump? My impression has been that aquarium pumps don't put out much pressure. If yours is suitable, could you please let me know its make and model number? If the flow was too low, I believe I could use multiple pumps to make up for it.

Thanks!

Paul
Click to expand...

Hi Paul

I don't know pressure & flow, it says

Medo Compressor, 46W
Nitto Kohki Co ltd
No 40604929,

that's all, plenty pressure for my arm, tho,


Sorry I can't be more helpful

cheers :drink:
 
#7
slowmotion said:


Hi Paul

I don't know pressure & flow, it says

Medo Compressor, 46W
Nitto Kohki Co ltd
No 40604929,

that's all, plenty pressure for my arm, tho,


Sorry I can't be more helpful

cheers :drink:
Click to expand...


Thanks for checking for me, but I looked it up on the web (http://www.medousa.com) and it appears that it puts out less than 5 psig. Medo makes a compressor that puts out 42 psig, but its flow at that pressure is very small. They are quite quiet, though. Being linear piston pumps, I would also assume that they would be very reliable. I'll keep them in mind, should my current pump fail.

Paul
 
#10
I've been looking for a compressor as well. I have an ET2 that I'd like tur run at a higher pressure, and I also have the platter air-bearing from a Maplenoll Athena that I'm hoping to use in a semi-homebrew table.

From everything I can tell, the Silent airbrush compressors are more or less the same principle as fridge compressors, although I don't know whether both are oil-free (I assume that the airbrush units are, but it's been a while since I've looked). I haven't been able to bring myself to drop 4-500 on an airbrush compressor, so I've been hoping to come across someone that has tried the the fridge compressor route. With a cheap 5-10 gal air storage tank to serve as a smoothing resevoir, I would think they'd work well.

The only downside is that you'd have to fabricate the connections, since you'd probably have just bare pipe-ends if you used a pulled fridge unit.
 
#11
If you go the fridge way, use bi-cone couplings. Also, provide some fan for the compressor, they tend to get hot. Better is to search for a compressor that has been used for a refridgerated cell (like at a butcher shop). These tend to come a complete units: compressor, radiator with fan and a small buffer. And couplings. I use one of those for my etch tank.
 
#12
If you only need a modest amount of air, why not have a look at a 12 volt electric tyre pump that normally plugs into a car cigarette lighter socket? They are available in a range of prices and qualities. They are a bit noisy though, so you would want to put it somewhere remote and run a hose from it. Plenty of pressure though. Also you night want to make a litte hole in the plastic case so you can put a dab of oil on the underside of the cylinder bore and the big end bearing so it will go the distance. I have seen them for as low as AUD$7.00
 
#14
Prior to audio, I had a life designing air quality analysis hardware for the US National Park Service. To move air through the air samplers, we needed a pump that was oilless and reliable at a modest cost.

Having about a thousand of these systems up and running 24/7, exposed to all kinds of weather made for a very rigorous test.

The winner was GAST, new about $200 usd. Rebuild parts easy to come by. Often sold used at places like C&H Surplus in Southern California. New in the US at WW Granger, a nation-wide industrial supply house.

One sixth or one eighth hp motor compressor should be plenty good.

Pressures up to 100 psi are not a problem. Add an inlet filter, muffler and a small storage tank to get rid of piston surges and you should be all set. You will still want to use an air dryer of some sort either cartridge or if you are feeling really DIY a refrigerated dryer.

Having high pressure available is an advantage.... it lets one use gas laws to remove water..... dry air for instruments is usually a good thing.

Regards
Cyclotronguy
 
#15
PUMPS.

Hi,

Pressures up to 100 psi are not a problem. Add an inlet filter, muffler and a small storage tank to get rid of piston surges and you should be all set. You will still want to use an air dryer of some sort either cartridge or if you are feeling really DIY a refrigerated dryer.
Click to expand...

Thanks for the info.

I suppose this is the company you refered to:

GAST

Looks like the ticket for an airbearing TT or tonearm.

Thanks again,😉
 
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