what impact wrench should I buy?

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  #1  
Old 10-29-02, 12:09 PM
bledsoe
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what impact wrench should I buy?

Hi, I originally picked up a cheapo $30 impact wrench, capable of putting out 260 ft. lbs or torque. I have a 13 gallon compressor, does the trick. That couldn't get my lug nuts off of my truck, so I picked up a $100 wrench capable or putting out 500 ft. lbs and even that one couldn't get the nuts off! The nuts were'nt really on there too hard, but still, I want an impact wrench that can handle anything. What would you guys recommend? and should the 500 ft. lbs wrench be able to handle anything???

Thanks guys
 
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  #2  
Old 10-29-02, 12:54 PM
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How much PSI does your compressor put out? It's really not the volume of the tank, but the pressure the compressor can build.
 
  #3  
Old 10-29-02, 12:59 PM
bledsoe
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the compressor holds at 125 psi, but the wrench is supposed to be run at 90 psi. What do you think?
 
  #4  
Old 10-29-02, 04:47 PM
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Tried and true IR 231

Larry
 
  #5  
Old 10-29-02, 08:07 PM
Joe_F
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You're missing the point.

The critical thing with air compressors is CFM delivery. If the tool exceeds the output of the compressor, you can have a 8000 dollar air gun, you'll get no where in a jiffy.

Most air guns use around 4 CFM (cubic feet per minute) at rated (typically 90 PSI), so as mentioned, post what CFM output your compressor has at both 40 and 90 PSI. If you are unsure, consult the owner's manual or call the company.

Tank size is important, but CFM output is more critical.

I have a Husky air impact gun. (Home Depot). This is made by Florida Pneumatic who in turn partners with Fuji in Japan to make it for them. I believe Sears/Craftsman uses the same vendor and IR also makes theirs in Japan, could be the same too (depending on the model).
 
  #6  
Old 10-29-02, 08:12 PM
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about any ignersol rand 1/2 inch drive impact is plenty capable of handling most task and they last a long time, you will still run into the occasional bolt that a 3/4 impact is needed to break loose but not very often, you should concider getting a compressor with a larger tank if you use airtools much so it is not having to constantly run to try to keep up.
 
  #7  
Old 10-30-02, 07:12 AM
redneck
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I got a Chicago Pnuematic 1/2" that has done everything I asked it to do. Once had a buddys truck with lug nuts that my gun would'nt touch. Tried a mechanic friend's 3/4 air and a 3/4 electric that he claimed would break any thing, Ended up using 3/4 breaker bar with 3ft piece of blk iron pipe for cheater bar--came off like butter. Lesson, airtools are great--but have limits!
 
  #8  
Old 10-30-02, 09:25 AM
bledsoe
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Alright, it's a 13 gallon, 5.5 CFM at 90 psi compressor(turns on wayyyyy to often when using the impact wrench). The wrench is probably the same one that you have Joe, it's the $100 500 ft. lbs capable wrench. I'm not home now, so I'm not sure of the CFM spec on the wrench. Either way, thanks for taking the time to reply on this. After reading a few things on the web it sounds like I need a compressor that'll put out a higher CFM, like the 7 to 9 range. And I definately need bigger than a 13 gallon tank! Sound right to you guys?
 
  #9  
Old 10-30-02, 09:27 AM
bledsoe
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I meant to include that the wrench was the Husky from Home Depot and the compressor was also a campbell hausfield from the depot...
 
  #10  
Old 10-30-02, 09:44 AM
Joe_F
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My compressor is an 18 gallon 4 HP Sears/Craftsman (made by DeVilbiss). It's rated at 8.4 at 40 PSI and 6.2 at 90 PSI.

I'd step up to something in this range and CFM output. Should be fine then.

The HD gun is about 4 CFM average from what I remember...
 
  #11  
Old 10-30-02, 05:36 PM
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if you are going to use airtools alot i would recomend you get a compressor with atleast a 60 gallon tank it is well worth the extra investment and in an upright doesnt really take up much more floor space than a smaller compressor would and not necassarily cost that much more depending alot on which brand you buy.
 
  #12  
Old 10-30-02, 10:39 PM
knuckles
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I agree with bejay. Buy the largest (both tank size as well as HP/CFM rating) compressor you can possibly afford. Avoid direct drive models if possible. They're noisy as all hell. For heavy use, go for a 5HP/60 gallon upright w/ belt drive & a cast iron pump. 2 stage is more desirable than a single stage.

I have a 12 year old Campbell Hausfield 5 hp/ 60 gallon upright at home. It's seen severe use over the years & it's never given me any trouble. I paid $399 for it in 1990 at the now defunct Hechinger home improvement center.

I run a 30 year old commercial 5 HP/ 80 gallon Keystone compressor at the shop. The only thing we've ever done to it was replace the drive belts & change the compressor oil. It'll keep up with the most demanding air tools (DA sander, 7" pneumatic grinder, etc) with no problem.
 
  #13  
Old 10-31-02, 07:04 AM
bledsoe
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OK, my impact wrench says 3.5 CFM on the box. Does that mean it's only capable of using 3.5. What exactly is that number referring to? Also, knuckles, what is the difference between 1 and 2 stage?

thanks
 
  #14  
Old 10-31-02, 09:03 AM
Joe_F
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3.5 CFM is the amount of air that the wrench consumes. (Cubic feet per minute)

In turn, the next question is what is the rated output in CFM Of your compressor at 90 PSI (typical working pressure)? As I said before, look in the owner's manual, on the unit itself or call up the company and ask them.

1 and 2 stage refer to the amount of times (stages) the air is compressed. 2 stage compressors are better, but they cost more.

For most home use a single stage compressor is fine.

I suggest you search the forum archives for information about air compressors and tools, I personally have answered these questions many times in the past.

Also Home Depot publishes a good guide that they used to put in the tool corral in the store. I'm sure if you type the subject on google.com you'll get some hits as well.
 
  #15  
Old 10-31-02, 10:29 AM
bledsoe
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Ok thanks. The compressor is rated at 5.5 CFM at 90 psi, so it sounds like that's more than enough for the wrench, which requires 3.5 CFM. I'm starting to think the wrench is falsely claiming it can put out 500 ft. lbs..... or perhaps the compressor isn't actually putting out 5.5!
 
  #16  
Old 10-31-02, 05:38 PM
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What is the inside diameter of your air hose?If its 1/4 inch it's too small.You need more flow and more storage capacity a 13 gallon tank is very small.They also make hi flow couplers which may help.You will also never see 90 psi in an auto shop more like 125 to 175 psi.Good Luck
 
  #17  
Old 10-31-02, 11:26 PM
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Take a look at this basic air hose pressure drop chart and it will surprise you.
www.tptools.com/StaticText/air_consum.asp

You not only need to use the largest hose but keeping the length as short as possible also helps. Last of all but not least don't forget to lubricate your air tools for maximum output.
 
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