I am thinking about buying a small electric air compressor for occasional household use, filling tires, maybe someday doing some spray painting, etc. Some newer models are advertised as "oilless" (and thus lower maintenance) -- is that a significant advantage? I have never had an air compressor, is checking the oil a big deal? I have never considered it a horrible burden with the lawnmower or the chainsaw. Thanks, -- H
Heathcliff wrote in news: snipped-for-privacy@z24g2000prh.googlegroups.com:
I may be wrong (I often am, it seems) but I always thought the reference to oilless meant the air - as in no oil in the compressed air.
Air tools require oil, whereas spray paint most defiantly does not.
Indirectly it does. With an oil type compressor you need extra filtration to feed your spray guns, plasma cutters and anything else sensitive to oil in the air. With an oilless compressor there isn't any oil to carry over into the air supply. An advantage to the oilless compressors for some applications is their ability to work fine in any orientation vs. an oil type which will leak oil and/or not get proper lubrication and seize.
It is more than just checking the oil. At low temps you could easily trip the breakers as the oil is thick and gives added resistance. Oilless is actually higher maintenance as you will need to rebuild it more often. For someone like me who does lots of construction projects outdoors in the winter this is important. For most household uses I would recommend the oil lubed models.
Oilless also has higher CFM ratings for the equivelant compressor and no breaker tripping in freezing weather.
No, it is no oil in hte crankcase. They use a Teflon ring or something similar so oil is not needed.
In certain applications, hospital, clean rooms, etc. the oilless type of compressor is used to eliminate possible contamination.
For the home shop, it all depends. Oil type are quieter, last longer, but cost more. If you use the compressor a few minutes here and there to fill a beach ball or check tire pressure, and maybe a brad gun, any of the small units will do. If you use air wrenches and spray guns, different scenario.
Oil type cost more??? Total bunk, the cost of a compressor has nothing to do with being oil type or oilless, it has to do with quality and capacity. I've seen big diesel powered oilless towable compressors ~350CFM I think, and I can assure you that they are far more expensive than an oil type of the same capacity.
They WANT you to think that checking oil is a major big deal..... The advertisers want to brainwash you. This is similar to the time when they advertised faucets as "Washerless". They wanted you to believe that washers are BAD. What they really did was replace washers with cartridges and rubber cups, which wear out just as fast (or faster) and cost twenty or more times what washers cost. Faucet washers cost 50 cents each, cartridges cost about ten bucks each, or more. There never was any advantage, in fact I still prefer washers, not only for cost, but also because they are often easier to change and there is much less inventory needed.
Oilless compressors are similar. They cost more and will die long before an oil filled compressor. Most of them are just cheap junk.
Big deal, I paid $100,000 for my big (900 cfm) compressor, $65,000 for my small one, but neither is suitable for my home shop. A valve body cost more than my home compressor.
We're talking home shop, infrequent use by a weekend handyman, low end starter stuff, not industrial duty. Porter Cable pancake versus larger 220V cast iron head. Be realistic to the topic at hand please. .
If you are deaf, buy either. If you have any hearing at all, DON'T buy an oilless. If you do, you will very soon be deaf. They are obnoxiously loud, and wear out fast. Buy a good oil crank case model, and buy over sized so it doesn't have to work hard, or it will also burn up quickly.
My experience from going through half a dozen compressors before I bought a decent sized oil crank case one.
Steve
"Edwin Pawlowski" wrote
You sure know how to make a fella feel good. For a while there, I was thinking some slick snake oil salesman had taken me for $75k for my garage unit I use to air up my riding mower tires.
Thanks, Ed.
Steve ;-)
Both have oil. One is splash lubricated, and needs to be checked once a year or so. The other has the oil soaked into the bronze. Which has a lot less oil to work with, and the "oil-less" really isn't without oil. They just don't tell you about the oil, is all.
I'd go with the splash lubricated one, and check the oil once or twice a year. Annual oil change is good, if you use the compressor very often.
Thanks to all for the information and advice. The noise factor is a consideration. I remember once I used one of those cheap airless paint sprayers to paint a bookcase. I thought it would be just the thing because of all the surfaces on a bookcase. I was shocked by the amount of noise the thing made. I put the second coat on with a trim roller.
Cold-weather performance is also a concern, I would like to be able to fill up the tires in January.
The other concern I have is, how much oil comes out in the air? One of the things I had in mind was to use it to blow dust off of screens. I have many eave vents, on account of the whole house fan, and they are covered with window screening to keep wasps out of the attic. Dust builds up on the screens. I was thinking I could rig up a piece of pipe and use the compressor to blow the dust off the screens. (Vacuuming them from the inside would be extremely awkward.) But if that would make the screens oily it would defeat the purpose.
For what it's worth, I two oil-less fail, each within 4 months of being new. Finally went with oil type and that was 12 years ago. Never another problem. Maybe they are better today, but I won't ever buy another one.
Have you actually looked at an oilless compressor, or are you just guessing? Where is the bronze bearing you are talking about?
I have an oilless Sears compressor. The motor and crank bearings seem to be sealed ball bearings, so no oil is needed there (unless you want to count the oil that is part of the grease that is packed into the bearings). The piston rings are apparently some sort of graphite that slides dry on the cylinder liner. Thus, the air is not exposed to oil at all - which is the real point of an "oilless" compressor. No bronze bearings in sight.
Oil-lubricated compressors have a crankcase, and use oil lubricated bearings and the piston is oil lubricated. This apparently gives lower piston wear and longer time between rebuilds, but you end up with a bit of oil in the compressed air.
Dave
Don't compare that to an oilless compressor. The airless paint sprayer that I tried once was incredibly loud, but it didn't have a rotating motor - it basically had an AC-powered electromagnet buzzer that pumped the paint. Oilless compressors have rotating motors with bearings; they are not as loud as that.
On the other hand, oilless compressors tend to be direct-drive and run a small piston fast. Many oil-filled compressors are belt drive and run a large piston much more slowly. They're quieter.
An oilless compressor shouldn't have any oil in the air to start with. If you get an oil-filled compressor instead, you should be able to remove the oil with an inline air filter.
Dave
Why would anyone on usenet want facts?
Even without an inline filter, you can certainly blow off screens with an oile type compressor without ever even noticing oil. Reading this thread, you could get the impression that they spew oil out like a paint sprayer or something. That's not the case. For some applications, you need to be concerned about the tiny amount of oil, but blowing off screens or parts, etc is fine.
You are comparing pancake compressors to stationary compressors. Oil filled does NOT necesarily mean belt drive. Portable compressors tend to be direct drive, regardless of whether they are oiled or oil-less. Stationary and larger horizontal compressors are almost always beld driven. Look at the Dewalt, Porter Cable, Hatachi lines. The small, portable compressors, oiled or oil-less, are all direct drive. If portability is an issue, then the way to go is direct drive with a small tank, but high CFM ratings.
There is not much oil coming through an oil lubed compressor. The only place this has any concern would be when paining.
Will the compressor be in a garage? If so, attached or detatched garage? If you have a dedicated line just for the compressor and it is a 20 amp circuit you should be okay. If you are going to do some serious outside work in January, then you would be better off with an airless, especially if you need to run extention cords.
You would get less than a drop of oil on a house full of screens. A simple filter would elimiminate this problem. An auto body shop, which uses the compressor all day will only get an ounce or 2 of oil all month. Oil in the air is not an issue until you are using it to paint something. Please note that the amount of oil in the air is so minute that power air tools need to be oiled daily. In fact, the best way to oil them is to put an oiler in the line!
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