First Air Compressor?

[Longhunter7]

Gentlemen,

I am in need of an air compressor for the shop, and I need some advice!

I am looking at a Sears Craftsman, 6 hp, 33 gallon, 150 psi, single cylinder, and oil free.

It is available in an upright or horizontal version. Is there any advantage to either style, or is it just a matter of footprint, (floorspace)?

Is 150 psi enough for most jobs?

Is this an overpriced piece of junk or is it a decent air compressor?

Thanks for any advice!

[salemlampworks]

Hello
I have been in the autobody biz for 30 years.There is no substitute for CFM.If you are going to use it for sand blasting(pressure blaster),and painting complete cars and trucks.I suggest nothing less than a 220 volt,5HP,2stage piston,60 gal tank.This will get you about 11.5cfm@90psi. Anything less and you will run out of air ,and have to wait for it to build back up.The diaphragm ones sears sells are good my dad has one, fast recovery but noisy.They are cheaper than piston but every time you need air ,you'll say to yourself I should have gotten the 2 stage.
For what its worth.

[pieter]

I will say I held out until I could buy me a big compressor.
6.5 hp, 80 gallon @ 175 psi. granted I had to wire in 220v, had to find a specialized place that had regulators that would go over 175psi and some other things like that...

But I will say it was worth it. I got my compressor at Sams Club and i think it was about $800. I do run out of air at times. I have sandblasted plenty with a pressure pot @ 90 psi. I can go for about 20 minutes when about half the sand is gone. Then i fill up and by the time I fill up, the compressor finally kicks off. I've run it for 8+ hours like this on many different ocassions and haven't had a problem.

I'd say, hold out till you can afford it. a 33 gallon is probably portable or a stationary unti. I guess it all depends on where you are going to use it and how much room you have.

Pieter

[Gordon Maney]

It is very exciting moving toward pieces of equipment that are so widely useful in automotive repair activities. The compressor, the acetylene torch, the mig or stick welder, the major lifting device. I smile as I consider how exciting this must be for you, getting to choose.

You don’t mention if you want portability, you don’t mention if you may move again someday, and we of course know that all things become compromise of some sort.

When I went to purchase my first major compressor, I had the good fortune of getting to talk to a salesmen. I say that somewhat tongue-in-cheek, as typically salesmen lie to you. This guy was unique in that he did not try to sell me a particular compressor. His idea was that he was responsible to tell you about compressors. His company sold all major brands new and also a vast array of used equipment. He did not care what you bought, and it seemed he did not care even if you bought from them.

His first remark was to say that horsepower ratings are not meaningful. People talk about their 5hp compressor, for example.

You need to look at the CFM rating and the pressure at which that rating is expressed. He said there are lots of compressors that yield high CFM ratings, but at high pressures and at very high speeds. He said that what you want is a compressor that can produce all the air you want at an easy, slow speed.

I ended up buying a rebuilt compressor, a DeVilbiss, that produced just over 19 CFM at 110 psi. It loafs when it runs.

So, I am not telling you what to buy. You may see this compressor as a stepping stone toward a larger one someday. Or, you may consider looking around carefully for a used one that is larger. Most of this decision comes from you and your situation. It is exciting in any case.

I remember many years ago when I brought home a first compressor, how fun it was realizing that I could fill a tire and operate a blow gun for cleaning purposes. And the sounds of the quick disconnects....

[JimmieD]

I just bought a Sears 919.184191 compressor. It was on the Sears yearend clearance for about $450 at about 20% off. Max developed: 7 h.p., max running 3.2 h.p., max 150 psi, 12.4 cfm @ 40 psig, 10.2 @ 90 psig. with 60 gallon reservoir. I'm expecting it to be just enough to run tools or a paint pot or plasma cutter, and maybe some media blasting.

Was going to buy the next lower rated unit but salesman showed me how much more I was getting for about 50 to 75 bucks, so.....and also a major point: the larger unit had a MUCH stronger warranty, with the ability to cheaply extend for a little more $.

I decided I wasn't going to get a lot of chances, so buy the best I could in each category of tools while viewing the overall budget. Because the compressor is the heart of several other tools or systems it seemed best to buy the better unit and as good as I could afford, now.

Bottom line: I suggest you buy the best you can afford from a quality company with a sound reputation and a good warranty policy.

[MoparNorm]

...buy the largest CFM, compressor that you can afford. If you do it right, it will be the last one that you buy. I think what you are hearing is that it is better to buy one expensive compressor than to be forced to buy an expensive compressor...AFTER buying a cheap compressor.
MN

[JimmieD]

Exactly! And remember, it is potentially the very heart of a huge tool system. Cheapo air guns and tools work fine for part time hobby use, but the compressor is an investment that will be used for years to come, long after tools are worn out.

[Longhunter7]

Gentlemen,

Thank all of you that took the time to respond! I was way off in my choice of compressors!

Doing it right the first time, is what I am all about!

The information provided, will help when I find the right one, thanks!

[MoparNorm]

Quality doesn't always mean expensive. e-bay, and other sources can score you a nice find.
http://photos.imageevent.com/moparnorm/w200frameoff/websize/DCP_1319.JPG

I got this little baby here for "free" by trading some work for a manufacturing company. 8hp, 25 CFM, 3 phase, 180 gallon tank.

As JimmieD mentioned, it is a system that you want to think about. On paper write down every air tool that you want to own. Get the manufacturers specs for those tools (all the CFM ratings) and add in a reserve cushion, plan on the potential of two tools operating at the same time, just as a mind exercise. Those figures will tell you how big to go and how small you can get by with.
With a small compressor you will be listening to it run almost constantly, not good for working around and not good for the compressor. With a large or correct size compressor the motor will actually be working less to keep up with the demand and running shorter because it can fill the tank faster.
Good Luck!
MN

[Longhunter7]

MoparNorm,

As a mater of fact, I was considering looking at used compressors!

I have all Winter to plan this out and weigh all my options and requirements.

I really appreciate all the expertise and proffesional advice here on the Forum!

[JimmieD]

I suggest that if you are considering buying used that you do some research ahead of time on parts availability from different manufacturers. Ingersol Rand has built some very high quality units over the years, especally larger 2-stage units similar to what Norm shows in the pic.

I believe parts are fairly widely available due to their common use in industry, and they used to be the mainstay of service stations, back when such places had garages, pumped your gas, checked your oil, washed your windshield and checked your tires....!

Always good to check abandoned service stations and if you find one there chase down the property owner and put in a 'haul it off' bid.

[MoparNorm]

...is a remarkable thing since the advent of the internet. Some guy in Frostbite Falls with three parts on his shelf for a 1972 IR can now let everyone know about his business. Most manufacturers have manuals in PDF format and a list of parts available, with price sheets.
MN

[Gordon Maney]

The guy who educated me on air compressors said that every big building you pass has an air compressor in it, unless it has several compressors in it. The purpose being climate controls.

Just as I type this, I wonder if all of those controls are now electronic, acccomplished by PLC [programmable logic controller] or now PC's. The compressors may still be sitting there, however.

My compressor is a Devilbiss 432, as I recall. Not all parts are available for it, but most are.

From what I know, Quincy is the very best, using disc valves. One important aspect of quality of design is the type of valve used.

We will see if we get some disagreement here on which compressor is the best.....

[MoparNorm]

...broke a reed, I located the part source on-line, but not the part, so I drove to the source listed, an little old timey place not far from me, owned by a little old timey man. There were new compressors, very old unsold compressors, and very old used compressors, parts bins galore and the smell of grease and oil everywhere. In short, my kind of place! The man apologized that he did not have my reed in stock, but he could order it from Illinois and have it here in a few days. I said OK, how much? I was thinking, $8-$12 for the part, shipping, etc, maybe $20-$25?
He said, $4.60. I'm wondering how you can talk to someone over the counter for 15 minutes, order and supply the part for $4.60??? He also called me every day until the part arrived. It will be a sad day when the BIG BOX stores replace the last American Mom and Pop Merchant.

As for Pneumatic controls every factory or large building with HVAC still has that type of system, especially the more modern computer controlled systems, they rely upon air to work the VAV (Variable Air Volume) control boxes and open and close the dampers. It is much more efficient than electric controls. You will find the electric controls on smaller buildings, but the huge office buildings and factories have air.

As for the best type? Anything big, heavy and American Made...= )
MN

[JimmieD]

As to parts availability I was more cautioning to stay away from a manufacturer that does not offer support. Day by day the old standby and trusted mfgrs. are turning to China sourcing so it's best to check parts availability AND origin of machine.

Reed design is not so important as reed materials and manufacturing technique. A low quality reed will fracture from metal fatigue or distort from heat/cold cycle and may not seal on the mating surface even when brand spanking new! A good quality reed valve can last for 30 to 40 years or more [think chainsaw].

A disc valve if of the rotary style, spinning to close and open ports, is very effective where close tolerances are used in the manufacture and where a quality bearing/bushing is used, and again, mating surface is fairly critical. Disc distortion can have an effect on performance but due to its spinning it is somewhat self-cooling and does not have the contact surface with cylinder head as found with reed valves.

There are still some old tulip valve units pounding away out there to this day and that design speaks for itself: l-o-n-g lasting! Not common.

The controls systems in large buildings have moved into areas of electronic monitoring and manipulations far beyond yeterday's simple air logic systems. Simple air logic is great, but limited without the related transducers and sensors to give a continuous real world feedback of system performance.

Todays large buildings, especially hotels and office buildings, have control sytems that would reduce the untrained to tears in a heart beat! Redundant PLC's programmed from a laptop computer, linked to a master control light board, linked to a color coded wiring system, linked to a fire control light board, linked to the building alarm system, linked to the fire suppression equipment, linked to Public Safety & Fire response units, and able to give an instantaneous readout of every single room individually, in addition to the secondary zone system readings, plus give readouts of the status and funtionality of each individual control! Yipes...and a big bucks occupation for those who have a bent for CONTROL/CONTROL/CONTROL.

Even the 'small' Davey & Kellog American rotary vane or screw type compressors have a complete PLC control system that is quite sophisticated, even being equipped in California with motion sensors to automatically shut down the whole system in the event of an earthquake! Rotary vane and screw types are unmatched for output volume but lack in actual efficiency, as bang for the buck on utilities useage. They're quite similar to the Paxton/McCulloch superchargers in design. Most common in manufacturing where you have assembly line processes using many dozens of air tools simultaneously or wherever a very high output volume is required.

Anybody remember the kits to turn a Volkswagen or other engine into a self-powered air compressor? 2 cylinders used to run self and 2 cylinders used to pump air, while maintaining engine reciprocating balance! Simple, cheap, effective and lasts for years and years.....not hard to fab up yourself either.

[Sickcall]

I have an intake and exhaust set up to turn a model "A" engine into an air compressor. I bought it with a sand blast tank which I never used. I never new they did the same on other engines as well. I wonder how well the old 230 would work? The plumbing would be pretty easy, but what about the pressure control. You can't stop and start the engine like an electric motor, so a pressure controlled unloading valve would be necessary.

[JimmieD]

Because of the V-dub's intake design it's not that hard to make a manifold change, where two cylinders receive intake mixture and two draw atmospheric air. On other engines that's pretty hard to accomplish. The Model A unit was designed for an emergency tire fill out in the middle of nowhere and then it was best to later change tubes so that gasoline content would not do any damage.

On the home made compressor an unloader and a flyball governor can be utilized to control reservoir pressures. A simple pop-off valve will work if it is the spring loaded type that lifts a valve off a seat.

In order to build your own compressor you want a modified intake manifold which will pump air to some cylinders or intake mixture to others sequentially to maintain engine balance. As only half the engine is producing power and the other cylinders are only pumping air, and are not receiving crankshaft thrust at TDC explosion, the engine firing order should be followed to choose which pump air and which feed the engine: 1 & 8 fuel, 4 & 3 air, 6 & 5 fuel, and 7 & 2 air. Flywheel momentum maintains rotation on non-firing cycles. Still kind of lumpy, so just tell folks, "Ya, it's got a racing cam....." :~ )

[MoparNorm]

ha!ha! engine compressors indeed!
I was at a fellows shop a few weeks ago, it was my first chance to see close-up one of the IR rotary, twin screw compressors, it was very impressive because of the quietness of the unit, you could hardly tell that it was running.
MN

[Gordon Maney]

Originally posted by MoparNorm
ha!ha! engine compressors indeed!
I was at a fellows shop a few weeks ago, it was my first chance to see close-up one of the IR rotary, twin screw compressors, it was very impressive because of the quietness of the unit, you could hardly tell that it was running.
MN

I suppose these are pretty expensive?

[JimmieD]

Originally posted by Gordon Maney
I suppose these are pretty expensive?

Which, Gordon: the loco weed or the rotary vane compressors? From the looks of things around here the former is affordable enough for any dope to buy, and the latter is best suitable for attachment to a bong for a large party. Look at the map and see that one of the closest towns in my area is WEED, California ha haha! :~ )

The Gardner Denver & Kellog American units and others are far from quiet when you get up into 25K CFM range! I could hear one of my units 1/8 mile away. The small units are very quiet in comparison and depending on the valve mechanism can be nearly silent in operation. On any decent sized unit the pressure unloader makes quite a bit of noise when it dumps, except when the air useage is at maximum. Even then we're talking some serious rpm's so the typical high-speed compressor whine is clearly heard. There's a technically a difference between screw-type and rotary-vane in some ways and the noise of vane rotation exceeds screw impeller noise. Could be that the IR unit that's so silent is actually a screw-impeller type rather than square-vane impeller.

It seems to me that with Ingersoll Rand you are very likely to get what you pay for, depending on what you pay for what you get.

[MoparNorm]

curiosity got the best of me so I went to the IR website. Naturally they do not list prices, but extrapolating from some cost savings information, I guess that the cost is in the $9,000 range, when new. From the Ingersoll Rand website:
Nirvana Compressor;
Matching a standard variable speed inverter with a HYBRID PERMANENT MAGNET; coupled with a time-proven airend, Nirvana represents a stunning advance in compressor technology. This new rotary compressor provides unparalleled energy efficiency at all speeds and offers superb reliability. There are no motor bearings, gears, pulleys, belts, couplings or motor shaft seals to wear out, leak or need replacing. In addition, there is nothing to get out of alignment. Nirvana will lower your operating costs with its dynamic efficiency. It offers truly transcendent technology. At full load, Nirvana will produce the most air using the least energy; and will continue to do so down to loads as low as 20%. Nirvana runs at 95% efficiency throughout its entire speed range.
Nirvana has fewer rotating parts than any other compressor in its class. The HPM motor uses no bearings and directly drives the compressor, eliminating gears, pulleys, belts, couplings and motor shaft seals.
Nirvana's exclusive Hybrid Permanent Magnet motor has revolutionized compressor performance by providing more air over a wider range with no increase in power consumption.



I think I'll wait until they hit e-bay....ha!ha!
MN

[Desoto61]

Figured I'd resurrect this thread vice starting a new one.

I need to move up to a bigger compressor. A friend of mine bought a compressor from these (http://www.eatoncompressor.com/page/page/504413.htm) guys, nice stuff, good ratings, and a great warranty. I particularly like the continuous run feature during heavy use.

I've been looking at their selection and I can't decide between their 5hp 60 gallon (http://www.eatoncompressor.com/catalog/item/504747/206949.htm)and the 5hp 80 gallon (http://www.eatoncompressor.com/catalog/item/504747/206953.htm) (single phase vertical tank either way). They have the same motor/pump combo so same output ratings. The 80 gallon adds an automatic drain but that's not a huge plus, I probably won't be using the compressor hard enough to really need it.

This is going to be used for normal hobby work in my garage: air tools, some painting, and running a small blast cabinet. I don't plan to do anything too big like sandblasting frames or body parts, at least not in the foreseeable future.

Is it worth the $150 extra for the 80 gallon tank or will I be fine with the 60?

[Ron in Indiana]

I had the same thoughts when it came time to replace our 40 year old compressor. I bought a 60 gallon Campbell Hausfeld with a 4 piston pump at Harbor Freight and before before anyone flames me for it, it's a good compressor. I have yet to run out of air running all sorts of body tools and grinders. The biggest thing is to get the most cfm rating to keep up with what you are doing. Without going down to the shop I can't remember what my cfm output is but like I said I have plenty of air and reserve.

[MoparNorm]

Ditto with Ron, CFM!
You might check your local Lowe's and Home Depots, they have some pretty large uprights and they are dealing right now.
Their own in-house demo crew, known as forklift drivers, do a pretty good job of dinging the merchandise. If you can find one with a scratch or minor missing part the manager will usually make you a deal.
One of my work compressors is a DeWalt that they lost the dip stick to. I got it 1/2 price, ordered the dipstick direct from the DeWalt tool site, $5.00
= )

[Deathdeelr]

I wouldn't dare knock CH. I bought one for the shop out in Cali when my company took over an operation out there. That was six years ago. Six years of operating a 1" impact gun, blast cabinet, assorted air tools. I was just there over the summer and she's still going strong.

My brother picked up a Craftsman 60? gallon upright, 2 stage 220 compressor from a Sears hardware for under $200. We replaced the unloader relay (it was broken hence the closeout) and it's been running for many years. Small air tools, blast cabinet, etc.

I built my compressor from a number of different sources. I have a Craftsman single stage 14cfm 220V 8 gallon unit I picked up at a yard sale for $20. I replaced the 5 hp stock motor (completely dead) with a 10 hp Robinson that fit the mounts perfectly. I then picked up a 50 gallon air tank from an estate auction that was missing the compressor unit but still had the mounting plates attached. I mounted the 8 gallon tank on the top of the 50 gallon horizontal. Now I have a fairly decent 14cfm compressor that's close to 60 gallons and I've run a portable media blaster, air guns, air over hydraulic lift, etc and have never run into a situation where I'm starving for air. The motor runs on a 220V/20A circuit and fires right up; no slow high amp start up. The oiled compressor is a 50%(?) duty cycle and so far has never seen half that much. I have a 1/2" 200 foot hose that can reach from it's location in my basement to either the driveway for outdoor work to the workshop at the back of the yard for foul weather work.

Harbor Frieght has great stuff and I'm going to be looking into a dual stage compressor head soon as I want to start hard plumbing out to the shop and I want to add a filter unit so I don't need to drag out the hose every time I want to use the lift or an air gun.

[MoparNorm]

Just a quick comment about Harbor Freight. 90% of their tools are cheap imports from China so watch the labels closely.

Often you can buy an old used American made compressor on eBay for less than a new import. It will give you many years service and not contribute to another North American losing their job.

[Deathdeelr]

If you take a really good look at most of the stuff we buy you'll find a label indicating it's made outside the US. We were just talking about Campbell Hausfield. Most of CH's regulators and air tanks are made in China. Briggs and Stratton, the pinnacle of US made small engines since the 40's farmed out their assembly and electronics to Japan and India years ago. In bought a 2500 series Chevy Avalanche; 496 cubes, limited slip diffs, whole 9 yards; a real man's truck, American's truck. The engine had a tag on the valve cover "Made Proud in the USA by Mercury Marine". The first time I had it in the shop for an oil change I wanted to puke. The leaf springs were stamped "Made in Mexico", the driveshaft had a silver sticker from "Shanghai Driveline Inc." The chassis tag had "Mexico" on the assembly plant line. I'm ashamed to say that the "Made in USA" label doesn't mean much anymore.

[Desoto61]

Yes, even the Eaton units I'm looking at. The are based in Ohio but I think they are just assembled there. I'm not sure that the main parts (motor, pump, tank) don't come from outside the country.

[MoparNorm]

Yes, even the Eaton units I'm looking at. The are based in Ohio but I think they are just assembled there. I'm not sure that the main parts (motor, pump, tank) don't come from outside the country.

The Eaton E Locker says Made in USA on it.
A few items are actually coming back home, so look at labels carefully. Some companies like New Balance, are finding out that china wasn't the bargain they thought is was and they are bringing about 30% of their manufacturing back to the USA.
Many European brands are actually made in the USA because Euro-Unions and labor rates are even higher than here.
Some examples of why label shopping can help our economy:
Hilti- Tulsa, Oklahoma.
Toshiba, Tulsa
Honda Lawn mowers, Marysville, Ohio.

[HRT5SLCFD]

I got this unit, comes with a 5 year warrenty, pumps 35 CFM. I love it. Had to redo all gauge of wire in the shop. Hint (just go big wire the first time).
http://i702.photobucket.com/albums/ww21/CRAWLERKID/carryall/PC080804.jpg

[Desoto61]

Is that the 7 1/2 HP V4 unit? I'm looking at their slightly smaller 3-cylinder version. It's rated at 24 SCFM @ 175psi vs 26 for that version, but is about $200 cheaper for the same tank size.

Unfortunately I didn't run bigger when I put in my current compressor, so I'll have to re-wire. But there's almost no size difference over the 5HP, just need a slightly bigger circuit breaker. Though at 32 amps running load I will have to be careful about what's on when that thing kicks on.

They're having a sale right now but I can't buy it for another two months or so when I get back home.

[Desoto61]

Ended up ordering this (http://www.eatoncompressor.com/catalog/item/504747/6112301.htm) unit. Still can't have it delivered till I return from work, but their prices aren't going down so I put in the order now to lock in the lower price.

file:///C:/Users/Damien/AppData/Local/Temp/moz-screenshot.pnghttp://www.eatoncompressor.com/i//DSC00646_1.JPG

It's probably overkill for what I'm doing but I should never need another compressor either.

[HRT5SLCFD]

Desoto, nice air unit. I have been putting in about 8-10 hours a day working on my 4 door, and have been using it for my plasma cutter, die grinder, angle grinder, and soda blaster most of that time. The comp. has not skiped a beat. I love this unit. I have run all my lines, filters, and connections. It cost me all most as much for the connections as for my unit, but well worth it. I don't ever think about running out of air. Anyway have fun with your unit.

James

[MoparNorm]

Ended up ordering this (http://www.eatoncompressor.com/catalog/item/504747/6112301.htm) unit. Still can't have it delivered till I return from work, but their prices aren't going down so I put in the order now to lock in the lower price.

file:///C:/Users/Damien/AppData/Local/Temp/moz-screenshot.pnghttp://www.eatoncompressor.com/i//DSC00646_1.JPG

It's probably overkill for what I'm doing but I should never need another compressor either.


No such thing as overkill...unless it won't fit in the shop....= )

[Desoto61]

No such thing as overkill...unless it won't fit in the shop....= )

Then I'd just put it in the shed behind the garage! Though if I go any bigger I'll run into issues powering it!

[HRT5SLCFD]

Well mine was so big, or maybe better said my rear shop too small. I had to run a line about 100' to reach the rear shop. The rear shop has only temp. heat, and the last thing you want is to have the water seperator to freeze up on you. Make sure it's not too hot or cold in your shed. As for the power I would run two sizes bigger wire than what you need. It will only cost a little more, but save time and labor in the future. It's funny how we grow into bigger tools as time goes by.

James