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Air Compressor help

sharpshooter

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Joined
Oct 24, 2006
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480
Location
West TN
I just stumbled across this website the other day and man let me tell ya I have really enjoyed it, now on to the question. I have been looking at air compressors for the last 2 months or so and I think I have narrowed it down to 2 specific ones, the first one is a Kobalt (from lowes) with a price tag of $794 and some change, its a 80 gal 7hp oiled motor 175 max psi 2 stage with about 17 cfm at 100psi(Lets keep in mind they give a 10% military discount). The 2nd one is a craftsman 80 gal 175 max psi (i believe 7hp) oiled motor 17.5 cfm @100 psi and its also a 2 stage, it goes on sale next week for about $807(not sure if sears gives a military discount). So my question is, do any of you fellas have either one of these if so I would be curious as to your opinions on them, I have always had goodluck with sears and their tools so I was leaning more towards the craftsman, any input on this is greatly appreciated
 
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cncjerry

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Jan 27, 2006
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120
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western PA
Link
Check out the above link the label on the tank is usually never what you are getting when you buy a air compressor check the motor tag that 7hp compressor may really only be a 3hp motor and you only get 17.5 cfm with the tank assisting it. The actual output with the pump running my only be about 10cfm if even that much. check the phone book and find a local air compressor dealer they will point you in the right direction. check this sticky at the top of this page to. http://www.garagejournal.com/forum/showthread.php?t=5024
 
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sharpshooter

Well-known member
Joined
Oct 24, 2006
Messages
480
Location
West TN
cncjerry said:
Link
Check out the above link the label on the tank is usually never what you are getting when you buy a air compressor check the motor tag that 7hp compressor may really only be a 3hp motor and you only get 17.5 cfm with the tank assisting it. The actual output with the pump running my only be about 10cfm if even that much. check the phone book and find a local air compressor dealer they will point you in the right direction. check this sticky at the top of this page to. http://www.garagejournal.com/forum/showthread.php?t=5024



thanks for the reply, I believe that they are advertised as 7hp with a running 3.5 hp
 

cc_rider

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Joined
Jun 22, 2006
Messages
223
Location
Austin Texas
Yep. Look at the MOTOR for the Hp rating; motor mftrs are required to put accurate numbers on the motor frame. I seriously doubt either unit actually has a 7 Hp motor at that price point. More likely they're 5 horse (or less); a 7 horse motor costs nearly double a 5 horse.

If you can find one, check out a local air compressor repair place. They are likely to have units for sale as well, new and used. And they are likely to have superior brands, like Quincy and Roll-Aire and others. You can probably find a unit with similar performance and cost, but overall a better unit: beefier construction, better cooling elements, etc. I had to replace the check valve in the top of my CH compressor, and got a far superior replacement valve from the local repair place; the quality difference was obvious, and now the thing runs like a champ.

The biggest problem with compressors, like any engine, is HEAT. Their duty cycle is based on how hot they get during operation, which is why they have things like 'two-minutes on, six minutes off'; it takes forever for the compressor to shed the heat. Run a compressor for a minute or so, and the tube going into the tank is gonna be too hot to touch, and will stay that way for some time; ask me how I know. Better units have cooling fins built into the tube(s), for better cooling thus longer duty cycles. You can plumb longer tubes, and some of us have even kicked around liquid cooling, but you get the idea.

An 80-gallon tank is nice and all, but unless you are running die grinders and such, a 60-gallon is probably sufficient, and will take up less real estate. Plus it can be moved; I have to disassemble my 60 gallon to move it single-handedly, but I don't think I could swing an 80. If you decide you need the extra capacity you can get a reserve tank; I've heard of people mounting a large tank (like those warranty return ones) in the attic or wherever to increase capacity. It'll make the compressor come on less often, but run longer when it does come on.

Good Luck!

c.
 
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sharpshooter

Well-known member
Joined
Oct 24, 2006
Messages
480
Location
West TN
cc_rider said:
Yep. Look at the MOTOR for the Hp rating; motor mftrs are required to put accurate numbers on the motor frame. I seriously doubt either unit actually has a 7 Hp motor at that price point. More likely they're 5 horse (or less); a 7 horse motor costs nearly double a 5 horse.

If you can find one, check out a local air compressor repair place. They are likely to have units for sale as well, new and used. And they are likely to have superior brands, like Quincy and Roll-Aire and others. You can probably find a unit with similar performance and cost, but overall a better unit: beefier construction, better cooling elements, etc. I had to replace the check valve in the top of my CH compressor, and got a far superior replacement valve from the local repair place; the quality difference was obvious, and now the thing runs like a champ.

The biggest problem with compressors, like any engine, is HEAT. Their duty cycle is based on how hot they get during operation, which is why they have things like 'two-minutes on, six minutes off'; it takes forever for the compressor to shed the heat. Run a compressor for a minute or so, and the tube going into the tank is gonna be too hot to touch, and will stay that way for some time; ask me how I know. Better units have cooling fins built into the tube(s), for better cooling thus longer duty cycles. You can plumb longer tubes, and some of us have even kicked around liquid cooling, but you get the idea.

An 80-gallon tank is nice and all, but unless you are running die grinders and such, a 60-gallon is probably sufficient, and will take up less real estate. Plus it can be moved; I have to disassemble my 60 gallon to move it single-handedly, but I don't think I could swing an 80. If you decide you need the extra capacity you can get a reserve tank; I've heard of people mounting a large tank (like those warranty return ones) in the attic or wherever to increase capacity. It'll make the compressor come on less often, but run longer when it does come on.

Good Luck!

c.



I have thought of going with a 60 gal and it would probaly get the job done, BUT I will be running a die grinder an air sander a blast cabinet a paint gun and an air board sander, so my motto is gonna be " I would rather go to the extreme than wish I had in the future
 

W-Cummins

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Jan 9, 2006
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Location
Iowa
cc_rider said:
Yep. Look at the MOTOR for the Hp rating; motor mftrs are required to put accurate numbers on the motor frame.

In the US anyway, no they don't... Infact if you look at most of these "6" and "7" hp?? motors, on the tag they will not list the hp, or list SPL as the HP Check it out, I have looked at probably 50-60 of them and they all seem to do it...

William....
 
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Acebusa

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Joined
Oct 25, 2006
Messages
4
Just buy a 25hp, screw compressor, this will solve all your problems, and your neighbors can hook into it and use it also........JK, if you had unlimited source of income it would be nice. Anyway an Important thing to look for in a compressor, is the Oiling most are splash lubracation, In this case it requires the push rod and crank to splash and oil the unit. Most pumps you will find are splash lube, and with out paying more for a pump this is what you get, they work well in most residental applications. Also consider the parts replacements. Ask if parts are avalible, and how reliable the source is for parts, if no one can give you an answer on where to get them, then think of the frusteration when your compressor is broke, and no one can help. Portercable makes a decent compressor, and parts are avalible easily. I use a curtis, but the cost becomes an issue for most. I bought it cause it has a pressure oil system, and is higher quality for my line of work. Check out curtis, they make good pumps, depending on what you want to spend.www.curtistoledo.com
 

l_bilyk

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Joined
Mar 11, 2005
Messages
1,773
Location
Ontario, Canada
sharpshooter said:
I have thought of going with a 60 gal and it would probaly get the job done, BUT I will be running a die grinder an air sander a blast cabinet a paint gun and an air board sander, so my motto is gonna be " I would rather go to the extreme than wish I had in the future

Those units you are looking at will struggle a bit with board sanders, while blasting larger objects, and with some less effiecient HVLP guns.
 

ZRX61

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Joined
Aug 15, 2006
Messages
28,716
Location
Solar Blight Valley, SoCal
Craftsman comps are usually made by Devilbiss. I found that if you forego the red paint job & Craftsman decal you can buy the same unit in gray with a Devilbiss decal for quite a bit less...
I have a Devilbis Pro4000 60gal/5(alledged)HP & the same unit in red with the other decal was almost $80 more... :)

If ya haven't bought a blast cabinet yet check out TPTools & their 960 model, (kickass catalog also)
 
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sharpshooter

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Joined
Oct 24, 2006
Messages
480
Location
West TN
ZRX I am looking at the black craftsman (the professional series i think) and yes I have already bought a cabinet ( paid 80 bucks for it brand new :) )
 
Joined
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Messages
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Location
charlotte nc
sharpshooter said:
ZRX I am looking at the black craftsman (the professional series i think) and yes I have already bought a cabinet ( paid 80 bucks for it brand new :) )
I got a big stand up (220Vac) from Home depot 6 years ago for around 400 bucks and have used it alot(blows leaves off sidewalk.gutters etc) with NO problems. Plenty of air 160/180 lbs
 
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