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Help Me Choose An Air Compressor
I want to do a leak down test soon and I'm beginning to hear suspension creaking so I will be acquiring air tools soon.
Again, the playing field is Craigslist, here are the contenders. Another one, but this one is modern. https://norfolk.craigslist.org/tls/6192059827.html Probably my 1st choice https://fredericksburg.craigslist.org/tls/6184971484.html What do you guys think? |
The older craftsman if still in good shape is to me a much better compressor. The newer one puts out just half as much air and could even be a diaphragm type. The newer 3.5 horse rating is also a joke compare to the older motor.
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Leak down test uses very little air and under 20psi to do the test. Pick a small and modern one unless you are a professional mechanic. That is my experience, everyone has different preferences.
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The $99 pancake compressor from Home Depot has served me well. Noisy little turd but pretty good otherwise
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I'd buy the amrox, as you wanted 110v power. My advice would be to buy a compressor that allows you to change the oil. My experience is that they run much quieter.
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I've R&R'd both the front and rear suspension on my 190 with nothing more than an electric impact gun and hand tools, no need for air. Even the impact gun was a luxury. Leakdown test is another story, but a tiny compressor should be sufficient for that.
For 220, you would need a pair of adjacent slots on your panel, as the 220V feed is two phase. You can have an electrician wire a 220v socket, and it would probably cost three times the price of the compressor. While it's not hard to DIY, you can run afoul of local building codes (not to mention electrocute yourself). As for using your oven socket, maybe, if the plugs match. But how long is the cord on the compressor? If it doesn't reach, a two phase extension cord is not a cheap item. |
Many points of view and understandable. There has been a generation that has known and lived with these limited smaller air compressors. I guess it is just a case of what you want to do both presently and in the future.
As for a test on a used compressor. The most important one is the time to fill the empty tank from empty. If it is rated at say nine cubic feed per minute output. It should fill the 20 gallon tank in just a little more than two minutes till shut down. |
Compressors must be drained after each use or rust can set up.
From the link below: "This is an old sears belt drive V twin air compressor that was never drained properly. When air compressors run humidity in the air they compress condenses in the tank. The resulting water sits in the bottom of the tank until it is drained. When not drained regularly the tank will rust from the inside out, when the tank is weakened enough it will often fail catastrophically." "Tanks have a maximum lifespan too. They still rot even with frequent draining. These compressors were built to replace in under 10 years. My personal shop compressor is built using a locomotive air supply tank ASME certified to 380PSI. The problem with that tank is, it's WAY too heavy for portability. So they make these thin steel tanks for portability thus the maximum life span. If a person really wants years out of a thin tank, they'll have the inside of the tank coated before the first use. Warranty void = yes. Life span increase = also yes. Pumps are another matter, few are built like they once were." WATCH THE ENTIRE VIDEO - HE OPENS UP THE TANK SURGICALLY RUST RUST RUST RUST!!!! YIKES!!!! https://www.youtube.com/watch?v=vdYimN5yOZc |
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I'll think about this for a bit. Thanks everyone. |
Take a look at the link below for our air compressors; happy to answer any questions that you may have!
Portable Air Tank - PelicanParts.com |
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The easiest way to visualize 1, 2 or 3 phase power, think of a 1 , 2 or 3 cylinder engine. With obsolete two phase power, the second phase sine wave is offset by 90 * ( quarter of a wave ) . The circuit was generally fed with 4 wires and motors had 2 separate windings to consume the power. https://en.wikipedia.org/wiki/Two-phase_electric_power With single " split " phase house power, sine waves are 180 * offset ( half of a wave ) . These systems have 3 wires but only use 2 depending on if 110 or 220 voltage is needed. No matter the voltage, everything remains consuming single phase. Motors have one winding that is used for run. ( There is sometimes a start winding that drops out after the motor is turning but that is beyond the conversation here. ) https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiXzuCKivjUAhXGyj4KHanNCPwQjBwIB A&url=http%3A%2F%2Fwww.globalspec.com%2FImageRepository%2FLearnMore%2F20122%2F240120SinglePhaseWavef ormTransparente0e210f2a73b4e2aa95274447e1b5892.gif&psig=AFQjCNHtmjLOfLLyT6KVjHAbdiLmzvDx9g&ust=14995 47921437169 With single phase house power, one can get 110 by selecting a hot and a neutral. To get the other "phase " of 110 you select the other hot and same neutral. To get 220 you select both hots. Three phase power is used for generation and distribution to your neighborhood. It is also used directly by industry. With 3 phase power, the sine waves are offset by 120* ( third of a wave ). This is very efficient because the power transmission is smoother and motors less expensive / more reliable. Motors have 3 windings. Quote:
Installing a 220 V outlet differs only slightly from a 110 v outlet. The actual wire is the same, the breaker needs to be a 2 pole ( we are using both hots ) and the third terminal is a safety ground not a part to pickup 110 V. If the device like a clothes dryer needs 110 to run the motor and 220 to run the heater, 4 wires must be used ( 2 hots , one neutral and a safety ground ) At higher voltages, a smaller wire diameter can be used Vs running the same load at a lower voltage. A three hp single phase motor running at 220 V will consume 13 amps , A 14 wire gauge extension will work though the thicker 12 gauge is better. ( for house wiring, 14 G is good to 15 amps and 12 G to 20 ) The oven socket will be rated for 50 amps so the plug won't work directly. You could make a jumper cord to a 220 V 15 A socket but in theory the cord should have it's own breaker. Breakers are rated for expected load and wire size. If a compressor that consumes 13 A locks up and the load goes higher, the breaker won't trip the the compressor will become a heater element. |
As for a compressor, the 2nd one is overrated and there is no way it is 3 HP, $ 120 is kind of high for what it is. Craftsman 3 1/2 HP Air Compressor. 125 psi, 25 gallon tank, 8.5 cu. ft/min @ 40 psi. $120
Most real compressors have the cubic foot rating at 90 PSI not 40. Rating the compressor at 40 gives the appearance the compressor is "bigger" As for the HP rating, the numbers on consumer units have been inflated for years ( same goes with lawnmower ratings, that is why they have gone to Ft / Lb torque ) The third compressor does not have a belt guard and is Taiwan / China made, I'd pass. For leak down a small carry 110 compressor is fine and might even be able to deal with intermittent impact tool use. A 2 or 3 HP _oil_ lubricated piston compressor would be better for impact use. |
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Also, can I just buy the cord or do I literally have to build it from scratch? |
It also seems the 220v compressor is just too much of a hassle to convert for home use.
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StayOnline.com Custom Power Cords (NEMA, IEC-320 or IEC-309) - Cable Assembly & Pricing Either way, the extension cord will cost more than the used compressor. |
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Looks like i'll get the weird V twin compressor then. |
A 110 volt compressor on a normal 15 amp 14awg wire gauge will only tolerate about one electrical older rated horsepower. It would take a 110 circuit Much stronger to handle the claimed horsepower of the newer compressor. The news is not the only fake thing out there.
There is also a chance that that 220v motor can be converted to a 110 by switching a couple of wires. That information should be on the motor plate. But you should feed it with a ten gauge wire then and a 30 amp breaker if it is. The original intent of using 220v was to keep the wire gauge size needed down. |
If you are going to get a 110 compressor, keep the power cord as short as possible then use more air hose, this reduces voltage drop that can burn the motor out.
In any event, a 220 cord of sufficient wire gauge won't be any more expensive than one for a 110 compressor. Have a look on a home center web site for bulk extension wire and plug / socket ends then make your own. It may even be less expensive to buy a pre made 110 cord and cut the ends off. None of this is as difficult as some make it out to be. |
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I bought Harbor Freight 2 hp 8 gal tank 110-120 volt and the typical 125 psi. As a handier supplement my Cambel Hasfield 220Volt don't remember the other specs but the Motor and Pump are much larger then the Harbor Freight one. It originally cost $260 in 1980 something Dollars. If you go to Harbor Freight you can look at user reviews of the products. Likely the same with Sears or Amazon. You can look at the reviews and pic a model you like and then use that info to shop around. Some of the items I used to frequently use compressed air for that taxes the Compressor is using a Metal Cutoff Wheeled Tool or Grinding Tool. As a home mechanic I have seldom used pneumatic impact wrenches unless for some tough specific task. I mostly use Harbor Freight 12 volt Impact Wrenches (which are actually made for removing lug nuts/bolts; I have one in each Vehicle) and they have nearly always substituted OK for the penumatic impact wrenches. |
First, I'm not an electrician. That said, I've spoken with several of them about this issue. One told me that if you are planning on running welders, hot tubs or powering up an RV sitting on the driveway, you need to have your service upgraded from 100 amp to 200 amp.
Also, I found this website for converters, looks like this may be a possibility for you. https://www.110220volts.com/power/voltage-converters.html Does anyone know if a 220v device pulls more amps than a 110v? |
I wouldn't suggest a step up transformer for anything bigger than an electric razor. If you need 220, just have an electrician wire an outlet for you.
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For a decade, I used the HF cheap one w/ dual side tanks, 2 HP motor, and top handle. It appears to be diaphragm type (no belt). Worked OK for most jobs but say nailing fence boards w/ an air nailer required waiting occasionally for it to recharge. I painted a car door with it, and if you paint slow and careful it might keep up even on a whole car. Then it started not reaching cut-off pressure, running all the time. I suspect a cracked diaphragm or such. Been sitting until I take it apart someday.
I later got a larger 5 gal belt-driven Rand 4000 w/ horizontal tank and 2 wheels for $25 at a garage sale. When first tested on 120 VAC, the motor would often stall and trip the breaker. I re-wired for 220 VAC (single-phase) which is an option, and no stalling since. I ran a large drier cord (30 A?) 8 ft to a wall socket. I installed the socket where my former electric water heater used to sit in the garage (now use gas). Since a plug, I could relocate the compressor, but that is the only such socket at my house. But, I have used it to all around my 1/3 acre home (nailing fences, roof). I just chain 50 ft air hoses to reach. The air hose acts somewhat like a reservoir, so actually seems to help. |
Bill - as a follow-up to your post..... My compressor is on a dedicated 220 service in the shop (the compressor is screwed to the floor) but I wired it with a dryer-type plug. With 100 amp service in the shop I can easily unplug the compressor and plug in the 30' extension cord to the welder (I forget the wire gage but it's significant and heavy!) and run the welder pretty much anywhere in the shop. Works great. There isn't enough power in the shop to run the welder and the compressor at the same time along with the AC and other power tools and this way I CAN'T screw up and do that. So I think you've done exactly the right thing.
Dan |
Ok guys I have to come clean, I got the air compressor but it failed.
The capacitor blew, the motor is probably burned out. The motor was a dinky 1/2hp unit, it is powering a compressor of at least 2hp capability a V Twin, so I can either source a 2hp motor or just buy a another air compressor out there. I looked on ebay and craigslist and the price for a new motor, whether new or used in most cases cost more than the entire used compressor. Long story short the compressor is FAR to powerful for the small motor to handle. Either way, I might just buy either a new motor or another used air compressor. Shoulda got the smaller one instead of trying to get something bigger... :mad: Now i'm back at square one :uneasy: I really should of taken you guys advice, sorry. |
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but if you can get that electric motor replaced under warranty you might could just change the pulley ratios .... to match its abilities to the friction of the V Twin.... it would run more for sure... perhaps a temporary solution to get this job done while you wait for sales ... |
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Is this a good website for pulleys? https://www.grainger.com/category/v-belt-pulleys/sheaves-and-pulleys/power-transmission/ecatalog/N-hxd How do I go about doing this? As in finding the correct pulley style and size? Also what do you mean by running capacity? The CFM it can output? I would like for the compressor to put out a high enough static pressure so I can get the correct working PSI of 90. I'm aware working PSI is dependent on hose length and how much static PSI you have available. My fear is that even with the correct pulley set up, the compressor won't be able to get to the correct static pressure OR it will takes eons to do so. Should I be concerned about such a thing? What would you do in this situation? |
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IF you are going to try to do this.. which I only mention but do NOT advise... go to your nearest BEARing supply....which will usually also have pulleys and ask for the PAPER catalog of things like Browning power transmission .... You might need to make a step down mechanism between the motor and the air compressor pulley.... since it has a fan included in it i assume.. the load .. usage at the equipment... is important main factor.. but you mention other important factors... the length AND size of the hose.. can really make a difference on things needing constant pressure.. like a paint spray gun... which really needs a whip and a pressure gauge AT the sprayer's belt line to see if the system is providing the air capacity at the speed needed to do proper atomization.. ( of course I am describing the stone age... not the newer spray systems meant to save over spray ) You ARE Worrying about the correct potential problems... so a new minimum Five hp ACTUAL hp compressor may be what you need... and make sure you have the biggest of hoses you can afford... ( a problem finding the brass connection hardware may present itself ) which I hope someone will tell me how to resolve with my 5/8ths inside diameter hose ... The way they are allowed to describe ( which should be illegal ) causes many people to buy under what they need for their jobs... You will need to really research to make sure you get what you need.... ' over capacity' is a really good thing... some day you might want to hook up two loads at the same time... |
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However, I'll keep it the compressor for a spare or sell it. Same goes for the tank. I'll also swap the the motor to see if the compressor is even worth keeping. There's another one in much better condition and it isn't a hack job, it's a stock champion 2hp air compressor. I'm going to upload some pictures of it very soon, i'll step outside in a sec. |
I think you are going the right direction
but I would never again buy anything less than five hp for a shop compressor.. just my experience with smaller ones......check to see how much air tools use.. a LOT and some require a high pressure at the same time... good luck |
How about starting with
What would you like to be able to do?
Depending on what your plans may be, various air tools consume air by CFM, and if you choose tools that consume a lot, get a compressor that is up to the task. Otherwise your "quality time" with your car will be squandered as you wait for your undersized compressor to "catch up". Using tools are to get tasks done faster. If you are waiting on your compressor all the time, you may as well use hand tools. Smaller CFM output compressors are for smaller tools, mainly for intermittent use. Larger CFM output allows the use of more types of tools, including sanders, DA sanders, paint guns and the like. I have had an undersized compressor for over 10 years, bought new. Too small for most jobs I ENDED UP needing to do; just wishful thinking, I had to pass. My next compressor will be over 10 CFM capacity with a 60-gallon tank- and aside from sandblasting ships in drydock, I will be OK. For automotive, there is such a thing as "NOT ENOUGH" and "TOO MUCH"- it's difficult to do fine feather paint sanding on a fender with a horse of a "bull grinder" that would like to snap both of your wrists when you hit the trigger. My advice, for what it's worth- consider the CFM rating of the tools, THEN look for the compressor. The compressor will take up room-make sure it gets full use and not wind up just being something that is in your way. Cheers! snapped_bolt |
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It is amazing how much air is needed for things like a 17 inch straight line sander or a palm sander used with water.... and it has to be AT the tool... friction and line size and length can mess up the situation.. |
I've had a Craftsman "5-hp" and "7.1 CFM @ 90 psi" 20 gallon compressor for almost 20 years. I put ratings in quotes, because I know it's complete BS that it is 5-hp or delivers 7.1 CFM. I think the "claims" posted on compressors have gotten a bit more honest in recent years, but overall I still think they are totally bogus. The tools also lie, add at least 2 CFM for any sander or paint spray gun as to what it will really consume in actual use.
So...get as much as you can afford, and are willing to deal with in terms of rewiring your house demands. For me, I wasn't staying in my present location for much longer, so I bought a second mediocre compressor that also lied about its output. I have one running on one breaker in the house and the other one running on another breaker. They both feed air into the same line with a 3-way splitter that harbor freight sells. From there the line goes coalescing filter, and then a 1-gallon desiccant dryer and then there is a 10 gallon piggy back tank (only want clean dry air going to that tank because there is no drain on it). I keep the regulators on both compressors set so they never deliver more than 125 psi, which is the "limit" of the piggy back tank. The system is 1/2 lines until the last ceiling mounted hose real which is 3/8 and 50 feet, and has a total tank capacity of 60-gallons. Overall, it works pretty well, painting isn't an issue, DA sander is my biggest consumer, and if you keep going with it the compressor will keep running too, and sometimes they both kick in. The newer compressor has a tank limit of 155 psi on it's 30-gallon tank, so it tends to run much more, as it kicks in at 110 psi, and the old Crafstman doesn't kick in until 100 psi, and it kicks off at 125 psi. Is it ideal? Nope, but it gets me by as a hobby level user. |
This is spiraling out of control for no good reason. ( and not because of the compressor you bought )
From what I recall of the pictures, the compressor in question had a very small pulley on the motor relative to the pump. Please measure the OD on both. Where did you find a spec that this pump takes 2 HP? Is the motor data plate stamped 1/2 HP? Also please list the RPM of the motor. The capacitor that failed, was it in a plastic or metal can? When start or run caps fail they do not damage the motor directly, any damage only occurs if the motor is trying to start and does not trip a breaker / thermal overload. Does this compressor have an unloader? On smaller compressors this is a small ( 1/4" OD ) line that runs from the compressor head or tank check valve then to the pressure switch. This line is usually on the side of the pressure switch and is in addition to the tank pressure sensing line. When the compressor is up to pressure and stops, the unloader line relieves pressure at the pump so the motor isn't starting under a high load. ( Another trick when dealing with limited power, add a manual valve to the unloader line and leave it open until the pump comes up to full speed. ) This can still be made to work, it is possible to run a " 2 HP " pump with 1/2 HP motor, it will just put less air because the pump speed will need to be lowered. |
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This setup is less bad than you think. Air is a very expensive 4th utility ( Water, nat gas , electricity, compressed air.) Nearly all the expense of compressed air is the electricity to turn the pump. Equipment and maintenance costs are minimal by comparison. Staging compressors is commonly done in industry if wildly varying air consumption is expected. Tank capacity is your friend, the less starts per hour the better in terms of energy consumption. Over compressing air ( to a higher pressure then regulating it down . ) gives you artificial tank capacity at the expense of energy to power the pump. For home use this is fine, however in industry , it is poor planning. |
Welp, the motor is completely shot, the armature has been melted solid, no valleys.
I was going to buy another motor or compressor but, both Craigslist sellers aren't responding. This one looks interesting. https://norfolk.craigslist.org/tls/6214971956.html |
You don't need junk like that to do what you are going to do. Buy a new one for $99 from HF. You will be glad that you did.
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Armature as in the rotating portion of the motor? If so, this smoothness is entirety normal for an AC induction motor. Please post pictures of what you think is bad. And, read my recent post about needing more info. |
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Dayton is the house brand of WW Grainger used across many products, their electric motors are very popular for general use industry. ( Baldor is one of the really HD brands however ) This compressor is a real 3/4 HP as opposed to the 2 HP rated generics. It is also reconnectable to 230 making it a good value. A pressure switch isn't to fix the no shut off expensive. ( assuming it is actually getting to pressure and beyond ) Regardless, the compressor our guy has needs attention first. |
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Ok hold on one sec |
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On the 2nd picture especially, aren't there supposed to be little individual copper wiring visible, not just a blob of molten looking metal?
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The stator windings ( in the housing ) induce current into the rotor, the current flow in the rotor sets up an opposing magnetic field causing the rotor to turn. Not all motors have actual windings in the armature / rotor found in DC ( starter motor ) , universal and some long obsolete AC motors. Please read my other posts and reply to the very specific questions if you want to solve this problem. |
Look at the 2nd and 4 pic on the right. Pic 2 shows the rotor , pic 4 shows the electrical equivalent.
https://en.wikipedia.org/wiki/Induction_motor |
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Oh well i'll be... I want to use the compressor for pneumatic tools such air ratchets and impact guns, I plan on using it as much a possible for nearly any work being done to the car, |
I'm gonna check the Dayton out tomorrow.
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I feel bad because I asked two different people if I could see, their compressors but I'm only going to visit one person.
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Here are the two choices.
Dayton 3/4 hp https://norfolk.craigslist.org/tls/6214971956.html Champion 2hp https://norfolk.craigslist.org/tls/6163836545.html The Dayton doesn't have wheels, making it impossible to move around by yourself. Two people could move it but that's just far too dangerous and heavy. Think i'll get the Champion. |
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