how to use an impact wrench

[JHZR2]

Hi all,

I know Ive made a few posts asking a variety of questions about compressors, pneumatic tools, electric impact wrenches, etc... But in order to help me pick, I need to ask a really simple and stupid question - how do you use an impact wrench.

I know the operation of the tool, I understand how to make it go, and I know that I want one... but I dont know how to ensure that I dont destroy bolts taking them off, or ensure that I stay safe and not overtorque anything.

So I have a few questions:

-all impact wrenches have forward and reverse, right? (some dont mention it, but look like they have rocker switches)

-how important is ti to have variable speed drive? Does this significantly prevent you from destroyuing things?

-on an air or electric gun, say its rated at 300 ft-lbs, does that amount get delivered from the first impact? I wouldnt want to immediately shear off bolt heads because I dont have variable speed, and it immediately gets torqued so hard (assuming its seized) that it just snaps)

-If gettingone, is it really best to buy the highest torque you can get, or are you better off getting lower, say 250 ft-lbs max, so to ensure that nothing gets hit too powerfully... and if it needs more, buy a bigger one that goes to 400+ or take it to a shop?

Any info would be great... I think it will help me to size what I want and better resolve how to choose a tool for my application needs.

Thanks!

JMH

 

[The_Jeff]

My cheapo impact has "max power" reverse and three settings going forward. The most powerful forward setting isn't even 100 ft lbs, the lug nut spec on my cars. You want as much loosening power as you can have, if you break something loosening (and you've got it in reverse) it was jammed anyway.

You'll notice an impact slowing way down when the going gets tough, so it won't bust stuff as easily as you fear.

 

[JHZR2]

OK, good to know... Ive read that people can take heads off of 14mm bolts relatively easily using these things... Id hate to be removing a bolt and break the head off because I cant control the unit, but it seems that this wouldnt really be the case.

Thanks!

JMH

 

[Win]

I've never used an electric impact wrench, but have a few air impact wrenches and, in all candor, find that I do not use them very much. Once in a while I will use an air ratchet but for the most part, I find it about as easy to just get a long breaker bar (if you have space) and just be done with it.

If you are still considering an air compressor, you might want to take into account job "creep".

I have three compressors now because I got a compressor suitable for a particular task, but insufficient for later jobs that I came up with. I always needed a better (read: bigger) compressor than the one I had. I finally wound up with a big behemoth on wheels that will run anything, continuously, even at the end of a long hose. If I had just bought the big one to start with, I would have saved several hundred dollars.

It is nice to have a portable that you can carry around, but you will probably want a bigger one later.

 

[Car Luver]

I use an impact wrench to remove big bolts and lug nuts.rarely use it to do final tightening. thats waht a torque wrench is for. Impact wrench is a must have for a good shop.

 

[JHZR2]

I agree totally on tightening with a torque wrench... I just wasnt sure if these high power rated ones zip up a bolt to 300 lb-ft within a split second or if it takes a while... Since I dont really have a feel for it, I dont really know.

Anyway, in doing my research, Ivce noted in a few places that lug nuts should not be REMOVED with an impact wrench... Ive never seen anyone do it with anything else (except myslef, who uses the tool provided with the vehicle. What is the issue with removing a lug bolt with an impact? I would tighten it 100% by hand, BTW.

Thanks!

JMH

 

[Pablo]

Mine has 5 speeds forward and R. Simple. Just start low with tightening.

 

[uconn1150]

quote:

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Mine has 5 speeds forward and R. Simple. Just start low with tightening.

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What brand?

 

[Pablo]

I need to slow down a bit....I mean torque setting not speeds. It's a bottom of the line IR.

 

[uconn1150]

Yeah, I figured, but I knew what you were talking about. What compressor do you use?

 

[Pablo]

I use a LOUD Craftsman 35(+/-) gallon 120V, 15A+. vertical mobile compressor. I'd love a small quiet one, too. And then a huge stationary belt drive unit in a shed.

 

[Win]

I have one of the black vertical Craftsman's, maybe a 25 gallon tank. It's very quiet; it's actually quieter than the little 4 gallon red Craftsman pancake compresser.

 

[tom slick]

I have the same compressor as Pablo, very loud.

the rating on an impact wrench is the max torque it can muster. it is not instantly on tap, you'll hammer for a little while before reaching max. it will shear bolts if they are stuck. all the guns i've seen, including really cheap ones, are reversable, they would be worthless if they weren't.
get the biggest gun you can afford, you really cannot have too much power.