I also would like to know where you got a "quiet" oil-less compressor. ALL of the ones I hear are quite noizy and that's behind a cupboard door and a regular door (true not as noisy as with both doors open). But if you virtually can't hear it right next to you I WANT ONE.
DIY compressor
- Thread starter rogue_engraver
- Start date
KCSteve
~ Elite 1000 Member ~
I've got the little one GRS sells. It's similar to the one Oz posted. Runs pretty quiet but does (or did) make a pretty loud noise when it lets off. The fine folks at GRS saw a picture I posted of my bench and, noting that I had it right by my feet, made and sent me a simple little muffler for it that dropped that letoff from annoying to 'only scares the cats'.
If I run across one I might add a secondary air tank to my system just to give it a larger capacity. Don't really need it for my engraving but it'd be handy when I'm just using it as air to blow something clean and/or when I get around to getting a rotary.
If I run across one I might add a secondary air tank to my system just to give it a larger capacity. Don't really need it for my engraving but it'd be handy when I'm just using it as air to blow something clean and/or when I get around to getting a rotary.
KCSteve
~ Elite 1000 Member ~
Thanks Danny! 
FL-Flinter
Elite Cafe Member
Whoever invented the oil-less compressor should be tried for crimes against humanity!
Glen Dikes presented great input from the refrigeration side, my experience is the industrial side where "air compressor" usually means a 50+ horsepower rotary screw putting out 200+ cubic feet of air at 175psi.
Anyway, several things are of concern in these smaller units. The faster the pump runs, the faster it's going to fail, the hotter it'll run, the higher the risk of fire/explosion, the more moisture you'll get in the unit/lines/tools. I strongly suggest you avoid the cheap direct-drive compressors completely and especially the cheap ones. First off, for every good one there are 500 junk ones. Then you have other issues such as the low price means low quality parts and that doesn't just equate to shorter life span, it means running the risk of fire/explosion. Example of this is a cheap direct-drive unit purchased by one of my customers at a big box store. The customer needed a low volume air supply for laboratory use and saw this cheap oilless unit as a way to save money. The unit was loud and after the employees complained enough, they built an enclosure for it - it was still loud. The unit wasn't used much, cycled on/off about 10 times per 8 hour shift. About three weeks after installing it, the low-quality cheap pressure switch burned closed allowing the motor to continue running after the cut-off pressure limit was reached. Because the normal operation of the unit allowed it to run hot, the low-quality cheap plastic safety pressure relief valve had melted closed at some point prior to the over-pressure condition caused by the switch failure. The unit continued to run until the motor began overheating to the point where it eventually melted the internal wiring and caught fire. Even though the enclosure was adequately ventilated, the fire wasn't noticed by the employees for some time. End result was the few hundred dollars my customer saved buying the cheap compressor ended up costing them several thousands of dollars in property damages and medical bills for the employees.
Having specialized training along with over 20 years experience with compressed air systems, my best advice is to say that if you are not completely familiar with compressed air systems and the mechanical compressor equipment - for your own safety please don't mess with it! The high-speed and self-contained compressors have specific operational conditions that must be kept in check. Too much, not enough and/or the wrong oil as well as contamination from products it was previously exposed to can result in a explosion/fire. Diesel engines operate by using the heat generated in the compression process to ignite the oil in the cylinder - if the conditions are right, air compressors can turn into a diesel engine and explode with a tremendous amount of power.
The dangers are very real folks. About two or three years ago a small 20 gallon store-bought compressor suffered a piston ring failure that allowed oil to pass from the crankcase into the cylinder. The resultant oil misting combined with the normal high operating temperature of the unit resulted in an explosion that took out several feet of an 8" concrete block wall, all the windows and doors, caused the roof to collapse and killed one person and critically injured three others.
I have messed with old refrigeration compressors from both appliances and automobiles, they're okay for a novelty project but I would agree that the time and money invested in these things is far better off being put towards a high-quality unit that will last you a lifetime.
Glen Dikes presented great input from the refrigeration side, my experience is the industrial side where "air compressor" usually means a 50+ horsepower rotary screw putting out 200+ cubic feet of air at 175psi.
Anyway, several things are of concern in these smaller units. The faster the pump runs, the faster it's going to fail, the hotter it'll run, the higher the risk of fire/explosion, the more moisture you'll get in the unit/lines/tools. I strongly suggest you avoid the cheap direct-drive compressors completely and especially the cheap ones. First off, for every good one there are 500 junk ones. Then you have other issues such as the low price means low quality parts and that doesn't just equate to shorter life span, it means running the risk of fire/explosion. Example of this is a cheap direct-drive unit purchased by one of my customers at a big box store. The customer needed a low volume air supply for laboratory use and saw this cheap oilless unit as a way to save money. The unit was loud and after the employees complained enough, they built an enclosure for it - it was still loud. The unit wasn't used much, cycled on/off about 10 times per 8 hour shift. About three weeks after installing it, the low-quality cheap pressure switch burned closed allowing the motor to continue running after the cut-off pressure limit was reached. Because the normal operation of the unit allowed it to run hot, the low-quality cheap plastic safety pressure relief valve had melted closed at some point prior to the over-pressure condition caused by the switch failure. The unit continued to run until the motor began overheating to the point where it eventually melted the internal wiring and caught fire. Even though the enclosure was adequately ventilated, the fire wasn't noticed by the employees for some time. End result was the few hundred dollars my customer saved buying the cheap compressor ended up costing them several thousands of dollars in property damages and medical bills for the employees.
Having specialized training along with over 20 years experience with compressed air systems, my best advice is to say that if you are not completely familiar with compressed air systems and the mechanical compressor equipment - for your own safety please don't mess with it! The high-speed and self-contained compressors have specific operational conditions that must be kept in check. Too much, not enough and/or the wrong oil as well as contamination from products it was previously exposed to can result in a explosion/fire. Diesel engines operate by using the heat generated in the compression process to ignite the oil in the cylinder - if the conditions are right, air compressors can turn into a diesel engine and explode with a tremendous amount of power.
The dangers are very real folks. About two or three years ago a small 20 gallon store-bought compressor suffered a piston ring failure that allowed oil to pass from the crankcase into the cylinder. The resultant oil misting combined with the normal high operating temperature of the unit resulted in an explosion that took out several feet of an 8" concrete block wall, all the windows and doors, caused the roof to collapse and killed one person and critically injured three others.
I have messed with old refrigeration compressors from both appliances and automobiles, they're okay for a novelty project but I would agree that the time and money invested in these things is far better off being put towards a high-quality unit that will last you a lifetime.
I have to agree with metalchipper...buy a good air-compressor. I have a 30 gallon from Sears..it is in my root cellar under the dining room...I drain it every couple of weeks. The 30' hose runs up to a hole in the bottom of my window on the 2nd floor of my shop to a water trap..another hose..coming from the water trap across the ceiling with 3 connections..1 for my air gun..1 for my Graver Max..1 for my Lindsay Classic tool. I never had any problems. Keep up the good work.
My 2 Cents:
Small compressors are just fine for the kind of use we give it. Even the small oilless work great - if they have a tank. The bigger the better. You don't have to buy "junk" however. Sears often has there small units on sale for a $100. They aren't going to "melt down". Harbor Freight, has fairly decent units for even less.
It really is a good idea to just LOOK AT IT and make a value judgement. If it Looks junky, pass it up. If all the parts that should be metal, are, then fine. Mine is from Sears, and makes way too much noise, even in a cabinet with the door closed. Other "small units" I've had are just as noisy. The one listed above that is whisper quiet is an anomally. If its that small and that quiet - that is un-heard off. Unless he has a 75% hearing loss!! :>) But there is no reason to doubt his hearing or him.
I don't physically have enough room for anything more than a small unit with a "larger" size tank. It just fills the space. I had to sell my 30 gal 240V 180psi 11 sfpm unit, because it wouldn't fit.
Small compressors are just fine for the kind of use we give it. Even the small oilless work great - if they have a tank. The bigger the better. You don't have to buy "junk" however. Sears often has there small units on sale for a $100. They aren't going to "melt down". Harbor Freight, has fairly decent units for even less.
It really is a good idea to just LOOK AT IT and make a value judgement. If it Looks junky, pass it up. If all the parts that should be metal, are, then fine. Mine is from Sears, and makes way too much noise, even in a cabinet with the door closed. Other "small units" I've had are just as noisy. The one listed above that is whisper quiet is an anomally. If its that small and that quiet - that is un-heard off. Unless he has a 75% hearing loss!! :>) But there is no reason to doubt his hearing or him.
I don't physically have enough room for anything more than a small unit with a "larger" size tank. It just fills the space. I had to sell my 30 gal 240V 180psi 11 sfpm unit, because it wouldn't fit.
"I bought one of these little Chinese/Taiwanese oil-less compressors with receiver and regulator/filter/pressure gauge for AUD$ 79.00 (USD$73.00 at today's rate)."
G'day all
Leo, I think I was the one who put you onto these, I had the same opinion "if it lasts 12 months I'm in front" mine lasted 3 months before the motor burnt out hope yours lasts a little longer :], mean while I've gone back to my big compressor in the garage and airline to my back room, I have the compressor running on a 7 day timer it starts up at around 5.30pm and times out at around 11.00pm and 8am to 11pm on weekends, saves me having to go out and turn it on and off.
G'day all
Leo, I think I was the one who put you onto these, I had the same opinion "if it lasts 12 months I'm in front" mine lasted 3 months before the motor burnt out hope yours lasts a little longer :], mean while I've gone back to my big compressor in the garage and airline to my back room, I have the compressor running on a 7 day timer it starts up at around 5.30pm and times out at around 11.00pm and 8am to 11pm on weekends, saves me having to go out and turn it on and off.
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