Practical knowledge using air impact tools

[tangalora]

Not sure if this belongs here, but, my question is not car specific so be gentle with me if I'm posting to the wrong place (I normally only post to Infiniti Online Mechanic).

I need air impact tools (to remove the Q45 front engine crossmember, for example). I've always wanted them, so now's the time.

Today, I picked up a 20 gallon 220 volt Sears Craftsman compressor & air hose & impact gun for twenty bucks at a garage sale. I changed the oil in the compressor, properly wired the bare-ended wires to my dryer receptacle, and fired 'er up.

But, the gun just doesn't have any ooooumph. It wouldn't even remove the lug nuts on the front wheels today. Why?

Do I need a particular (i.e., better?) gun?Do I need more air per minute (what's a good cfm for air tools)?Is the 25-foot hose that came with it too restrictive?Note: I need the 25 feet (or most of it) as the dryer outlet is in the back of the garage while the car is on jack stands in the driveway.

I can easily get 115 psi output (before the 25 foot hose) as shown by both the tank pressure gauge and the output pressure gauge (see photo below).

May I ask those experienced in air tools what I should expect from air tools?Shouldn't air tools be able to remove lug nuts?Should they be able to remove suspension member nuts?Is it just that my gun is no good?Or, is the hose too restrictive?Is the CFM the important measure (or the pressure)?How can I measure the CFM at the end of the hose?

What is YOUR experience (and advice) for using air tools?

[DAEDALUS]

Get a better gun. The CFM recommendations will probably be posted on the tools or manual, but the point of having an air tank is so that with intermittent use it shouldn't be a problem. Always use impact sockets/extensions. Safety issue, plus a knowledgeable Sears clerk won't replace a broken socket that he thinks was used on an impact wrench.

You can put a regulator at the end of the hose, with a shorter hose from it to the tool, to see what the pressure drop is when you're using the tool.

[tangalora]

Thanks for the advice.I guess it could just be the gun.Does a better gun multiply the torque somehow?

I just realized the air compressor puts out more air at a lower PSI than at a higher PSI (see photo below). That is, at 40 psi, it putsout 10.3 standard cubic feet per minute while at 90 psi it only putsout 8.5 standard cubic feet per minute.

That makes me wonder if the gun (what do you call it) gives moretorque with air pressure or with cfm? Any ideas?

Should I use lower air pressure or higher air pressure to get more torque?

Another question is there seems to be a 4-position dial on the bottomof the gun (whatever it's called). I tried all four positions (none seemedto me to make any difference) but, does anyone know what thesefour positions indicate?

Is 1 more or less torque than (say) a 4?

[DAEDALUS]

An impact driver (or impact wrench) has vanes in the mechanism that drive the motor, converting the air pressure to torque. Maybe simlar to the exhaust side of a turbo charger, but with "hammering". A better impact wrench has a larger and/or more efficient mechanism. Use the highest pressure setting allowed by the tool you're using. A motor's CFM rating tells you how good a job it does in filling the air tank. The air in the tank is what the regulator controls and is what powers the tool.Just guessing, I'd say the larger the number, the greater the torque, though they're only relative settings, probably no values given even in the owner's manual.

Just looking at that thing I would have bet money that it is far too inadequate for what you need now. Look at the tools rated above 300 ft-lbs and you'll see they're substantially larger. The torque to undo a bolt that's been in place for 15 years is noticeably greater than the installation torque.

[elwesso]

You shouldnt experience any if at all pressure drop with the hose.... Ill take some more pictures today of my setup... But we have shop air up here, and about 100 feet away from the compressor I can get the same amount of pressure as I do to the port thats basically right on it...!

I was using a portable air tank on my impact wrench, and not a compressor. Id charge it up to about 160-170 PSI, and after it got down to 140 PSI id have to recharge because it woudlnt hardly do anything...

That said, I dont think 125 PSI is enough to properly use an impact wrench... Id think you need to look more around 150 or so.... However, if your gun works decently, I dont think youll need a new one... We've got some REALLY old tools around here (im using a very old B/D) and they all still work... SO that said, getting a new gun wont really give you MORE POWA.. Its more efficient, but the PRESSURE is ultimately what drives it! I dont know what you got, but its possible its not good enough.... Id see if you can get it to put out about 150 PSI then buy a new one...

And also, as robert said, GET IMPACT SOCKETS... Ill take some pics, but they are MUCH beefier than a regular socket.....

[elwesso]

The numbers are also for torque... 4 should be the highest...

I think probably in the owners manual there is a torque value or range for each number... Use the highest value for taking all them off, and use a lower number for putting them back on, so you dont put them on too tight....

[PoorManQ45]

I was using a portable air tank on my impact wrench, and not a compressor. Id charge it up to about 160-170 PSI, and after it got down to 140 PSI id have to recharge because it woudlnt hardly do anything...

Wow! You have got a commercial air compressor! Your Impact Wrench doesn't do much at 140psi? OMG. I remember seeing an Impact Wrench online that was designed to run at 160PSI. It was rated to deliver ~900 lb/ft torque. I've got one that is designed to develope 350 lb/ft torque at 90 PSI. It still works very well even when the pressure drops to ~50PSI.

Most "standard" compressors "only" go to about 125~150 PSI. That is plenty if you get tools that are designed to operate between 80~110psi.

At equilibrium the pressures will of course be the same everywhere in the system, but there has to be a pressure drop while using the tool.

Ya, I understand what you're saying. Air tools are not 100% efficient. I Have a 6 gallon tank/compressor combo with a regulator gauge on it. When I use the Impact Wrench, the Regulator gauge drops by ~10PSI. But the PSI gauge on the tank doesn't move the same as the Regulator. When you pull the trigger on the Air Tool, move your other hand around it. You should notice that there is a lot of air coming from it.

[tangalora]

... a knowledgeable Sears clerk won't replace a broken socket that he thinks was used on an impact wrench...

I'm wonderin' how you knew I (only) use Craftsman hand tools?

100 feet away from the compressor I can get the same pressure as I do to the port thats basically right on it

That's good to know. I measured the hose that came with the compressor. I thought it was 25 feet but it was more like 50 feet. I'd buy a larger (fatter) hose (if I need it) but I do need the 50 feet because of the distance from the outside of the garage to the 220 volt dryer receptacle.

At equilibrium the pressures will of course be the same everywhere in the system

Thinking about it a bit more, I should've realized this. If I think of the PSI like voltage or water pressure, once I open the stopcock, the pressure (voltage) should be the same throughout the system. It's the VOLUME (i.e., current) that must suffer from the long thin hose. I need the 50 feet, but, I may consider buying a thicker hose (and corresponding couplings). Are all coupling shapes the same? Some seemed slightly different to me when I stopped by the parts store this morning (to pick up the red locktite).

Quote »(im using a very old B/D)[/quote]What's a B/D?

Quote »but the PRESSURE is ultimately what drives it[/quote]Sorry for asking so many questions. I'm new to this.Seems to me a combination of pressure, volume, dial settings, and the mechanics of the gun are what is limiting my torque. The problem is which one. So far, the answer seems to be the gun itself ... I'll keep reading on.

Excellent analogy (easy to understand & agree with). This again implies the gun thingey (what's it called ... an "air impact wrench") may be the culprit.

The numbers are for torque... 4 should be the highest...

Thanks. That's what I'll set it on (it didn't seem to help but at least that's one setting I don't have to futz with ... I'll just leave it on 4.)

I think probably in the owners manual

I picked it up at a garage sale yesterday. Neither the compressor nor the air impact wrench gun came with any instructions. The lady who sold it to me said her husband passed away and she was selling everything in the garage so she didn't have any idea how it worked. Luckily for me all the hoses and regulator were attached so she gave me the whole unit for a twenty (she set the price and I just paid it as I absolutely hate haggling). Same with the air impact gun. I gave her another twenty.

Quote »And also, as robert said, GET IMPACT SOCKETS... Ill take some pics, but they are MUCH beefier than a regular socket.....

On the messy shelves at the garage sale, there were a bunch of really black thick battered sockets so I didn't even think of picking them up (all mine are chromed thin-walled shiny Craftsmans). I think (after reading what you say here) I should've dropped another twenty on those socket sets, huh?

Quote »Use the highest pressure setting allowed by the tool you're using.[/quote]Do you think that if 90psi is "allowed", then using 125 psi is better? Or is there a cutoff that basically shunts the air from the tool?(Maybe that's my problem?).

Quote »Look at the tools rated above 300 ft-lbs[/quote]Is 300# the torque number I should aim for in the gun to remove an engine crossmember?

Quote »A better impact wrench has a larger and/or more efficient mechanism. [/quote] I wonder if there is a way to TEST it (other than trying to remove something). I guess I could press the reverse button and tighten a nut such as the lug nuts and then test with a torque wrench how tight it got.

Are there any simple torque tests we can run ourselves? to determine the actual torque obtained?

In summary, based on your responses, assuming the gun below is capable, my setup should be able to remove tough nuts but it can't. So, I need to narrow down the culprit (bad settings, user error, low air pressure or cfm, bad gun, etc.).

[DAEDALUS]

On the messy shelves at the garage sale, there were a bunch of really black thick battered sockets so I didn't even think of picking them up (all mine are chromed thin-walled shiny Craftsmans). I think (after reading what you say here) I should've dropped another twenty on those socket sets, huh?

Yeah, it probably would have been quite a bargain, especially if there were metric ones in the sizes you need.

Quote »Do you think that if 90psi is "allowed", then using 125 psi is better? Or is there a cutoff that basically shunts the air from the tool?(Maybe that's my problem?).[/quote]Never thought of it but I assumed the tools did not have a safety feature like that. I think the makers only assume you will obey the limits. The more pressure, the more torque, at least until the tool breaks.

Quote »Is 300# the torque number I should aim for in the gun to remove an engine crossmember?[/quote]I just kind of threw that number out there as a guess. Without looking I assumed installation torque would be maybe 150ft-lbs max, and I doubled that number. Maybe 300-450 ft-lbs would work here and most other things. Crankshaft bolt is the highest torque I've ever put on any fastener, at 270ft-lbs.

[elwesso]

As usual I wasnt clear enough ( didnt post what I was thinking)

Allow me to clarify... The wrench would have to be really bad to not work... I realized today that most of the time I was running at about 120 PSI and it worked fine.. It was just "decreased" in performance.....

I guess being blessed with the attached beast, you think aynthing else is inferior

I was using an old school black and decker wrench..... More pictures will come as promised in another thread.

[tangalora]

I couldn't get any of the suspension member bolts off today. None.I could barely get to some of the nuts, even with a standard wrench kit. Even those I did get to would not budge a bit with the air impact wrench.

So, I'm resorting to plan B, which is composed of the following two steps: - Learn more about how these air impact wrenches generate torque - Pick up a larger set of wrenches, impact sockets, breaker bars, etc.

To determine the torque that the existing air impact wrench can garner, I found Universal Tool company on the web at: http://www.utsupply.com/viewpr...=2032

Apparently their UT-2210 air impact wrench is no longer sold, but, I was able to find a used Universal Tools UT-2210 wrenches for sale (see photo)on ebay (although I never did find a set of good pecifications): http://cgi.ebay.com/ebaymotors...34787

The nearest UT part seems to be UT-2147P (I'm guessing), having specs of: - "Limited Use" (designed only for the home & hobby, not commercial) - 1/2 inch Impact Wrench - Dynapact® clutch for high torque output - 8,500 RPM, 425 ft. lbs., 7-1/2", 6-1/2 lbs., $108.67

If mine did generate 425# (in reverse), it still wouldn't budge any of the 1990 Q45 front engine crossbar bolts holding it to the frame. - http://www.nicoclub.com/zerothread?id=77266 - ("www.nicoclub.com/zerothread?id=77266")

But, I suspect it did not generate anywhere near that amount of torque,so, that's why I'm looking to better understand the mechanics here.

I still don't know how to determine if it's actually generating 425 pounds, but, I learned (from the web) that SAE 30 extreme pressure oil should be used in the gun (about an ounce should be poured in an oil hole on theside somewhere). Also, after each use, that 30 weight EP oil should be addedto the air inlet and the gun should then be spun before storing. Since the previous owner of the air impact driver left us years ago (according to his wife), the UT-2210 air gun probably hasn't had oil for at least as long.

Also, about 16 oz of that 30 weight oil should also be placed in the air compressor (not the multi-weight 10W30 I put in there previously) as the multi-viscosity motor oil additives apparently carbonize inside the air compressure cylinders.

So it was my bad both for running the air compressor on 10W30and for running the air impact tool without oiling it (if I only knew then what I now know). Maybe (just maybe) that's why my setup won't generateanywhere near enough torque to remove Q45 front engine crossmember nuts.

I also learned that the 4 settings do regulate the air pressure at the baseof the air impact wrench. My problem (since there are no markings on the gun - they probably were on a sticker somewhere that's not there now) is how to determine if it's on #1 or #4.

After looking at other guns at Sears, I will assume the number on the dial which is closest to the air inlet is the actual number (#4 beingthe higher air pressure and #1 being the lowest).

I also picked up a set of impact sockets (not cheap), impact extension rods, and a wierd-looking 360 degree impact universal joint (which looks like a stick in a round tub instead of looking like a U-joint). Just to be safe, in casethe air impact tools continue to fail me, I picked up three lengths of pipe and two different kinds of breaker bars.

I'm hoping that at least one of these methods will break those nuts loose!

[p00t]

i did a search on google and eventually came across some similarly sized impact guns, the older snap on ones were rated at 140 ft/lbs. Newer models were around 240ft/lbs. I think its a good bet that your somewhere in the middle.

http://cgi.ebay.com/ws/eBayISA...73110

http://cgi.ebay.com/ws/eBayISA...42248

http://cgi.ebay.com/ws/eBayISA...22663

3/4" drive in is the 500 ft/lb area which might be what you want. this model has "oil daily" imprinted in plain site on the side of the unit lol. I think you should try oiling yours first!

http://cgi.ebay.com/ebaymotors...03915

interesting to note they all work at 90psi... I think its safe to assume your troubles are not with anything compressor side.

[tangalora]

Quote »they all work at 90psi... I think its safe to assume your troubles are not with anything compressor side.[/quote]Good (and intelligent) point. I'm sure 90 psi is available (although I have no idea how many scfm are really coming out at the end of the 3/8 inch 50 foot hose). Since the compressor is rated (new) to output double the stated 4 scfm needed to run most air guns (from my web search), I'm gonna lay off the compressor and concentrate on other things to better understand how to get the maximum torque and how come those bolts won't budge.

Quote »Newer models were around 240ft/lbs. I think its a good bet that you're somewhere in the middle.[/quote]That's likely to be accurate. The Sears store medium duty impact gun (which seemed about the same size, albeit many years newer) sported (an advertised) 345 foot pound rating. My research showed Marketeers lie tremendously on compressor horsepower ratings, so, subtracting 30% (or so) gets us to a realistic 250 foot pounds for a correctly oiled correctly working well fed (90 psi) air gun. Assume 50% less for an older not well fed gun gets me about 125 foot pounds (rough guess).

Now, the question is whether 125 to 250 foot pounds is enough to remove Q45 engine crossmember and transverse link bolts (which have not budged one bit yet), partly due to my sorry socket situation.

What I've done to rectify the sorry socket situation is to pick up three impact extension bars and a funny looking tube-in-a-tub universal which I hope gets me a impactful line to the transverse link & crossmember nuts.

Quote »I think you should try oiling yours first![/quote]Indeed! I researched this and found 30 weight oil to be recommended the most (although some recommended EP oil which would indicate some kind of hypoid gear oil). Same with the compressor (which cokes and carbonizes on multi-weight oil). Funny, why would a compressor be much different than an engine (which apparently thrives on multi-weight oil)? Maybe it's the temperature (I assume an engine is much hotter than a compressor, although I've burned myself on the fins on the compressor already so that might not be true).

At the Sears store, the instructions that came with the gun suggested oiling both from an oil hole on the side (1 ounce) and from the air inlet side. My question is why both? Do they get to a different area?

[tangalora]

Quote »What I've done to rectify the sorry socket situation is to pick up three impact extension bars and a funny looking tube-in-a-tub universal [/quote]Help me here as I'm brand new to air tools.

Is the set I picked up below sufficient to get the crossmember, motor mount, and transverse link nuts off? I found that I couldn't get a direct shot to the nuts with just an extension bar (plus someone, I think it was Wes, suggested that these black impact sockets and extension rods were stiffer therefore they transmitted more of the torque to the nut and less was expended en route).

What else (by way of tools) would I need to get those gosh darned nuts off?

[DAEDALUS]

I have no idea how many scfm are really coming out at the end of the 3/8 inch 50 foot hose. Since the compressor is rated (new) to output double the stated 4 scfm needed to run most air guns (from my web search), I'm gonna lay off the compressor and concentrate on other things to better understand how to get the maximum torque and how come those bolts won't budge.That's likely to be accurate. The Sears store medium duty impact gun (which seemed about the same size, albeit many years newer) sported (an advertised) 345 foot pound rating. My research showed Marketeers lie tremendously on compressor horsepower ratings, so, subtracting 30% (or so) gets us to a realistic 250 foot pounds for a correctly oiled correctly working well fed (90 psi) air gun. Assume 50% less for an older not well fed gun gets me about 125 foot pounds (rough guess).

The compressor power should have no practical impact on the effectiveness of the tool. It's the stored, compressed gas in the tank that drives the tool. A 20 gallon tank is essentially the same as a 100 gallon tank, as far as the tool is concerned, regardless of the compressor mounted to either of them, given equal regulator settings. The only difference is that a larger tank shows a smaller pressure drop with use, and the more powerful motor is able to fill the tank faster, so there's less waiting around once you cross below the threshold pressure. Neither are an issue with very intermittent use of an impact wrench, as long as the tank has more pressure in it than what the tool requires.

Hose diameter and length do play a role in the pressure drop between the regulator and the tool. A 1" ID hose has 9x as much area as a 3/8" ID hose. But I would think that this should not be the make-or-break feature of the system.

[tangalora]

The compressor power should have no practical impact on the effectiveness of the tool. It's the stored, compressed gas in the tank that drives the tool.

Makes sense. There's logic there.

I'm definately learning a LOT from this endeavor to garner more torque.For one, while putting oil in the gun sure makes a mess it seems to magically generate more uuumph now (after spitting out 30 weight oil out the front for the first minute or two after the thorough oiling).

When I set the regulator (at the compressor tank output) at 90 psi and the Universal Tool impact gun to #1 (see photo for assumed reference mark), it seemed to spin much faster (based purely on the audible sound) than it did at #4 (which seemed to be the slowest setting).

Does that definate sound (i.e., speed) difference tell us anything about the operation of the impact gun torque regulation knob?

Something is working better now.

After spritzing the nuts with Kano Sili Kroil, the newly oiled and 90 psi regulated impact gun now easily spun out all four motor mount nuts and all six of the nuts holding the torsion bar & what appears to be a sway bar to the transverse link assembly on a 90 Q45.

However, even the newly oiled impact gun set at 90 psi wouldn't budge the six front engine crossmember nuts (two of which need a 17mm deep socket which I had to run to the store today to purchase a complete set of). Luckily, I busted most of those nuts off using a breaker bar, two feet (literally, my legs and feet) and a three foot pipe extension (explained more fully in the Q45 oilpan R&R thread at http://www.nicoclub.com/zerothread?id=77266 ("www.nicoclub.com/zerothread?id=77266").

So, the impact gun was of some use but not as much as I'd like.

It would be nice to find some kind of inexpensive setup which would intelligently measure the true torque output of an air impact wrench.

[mixatonia]

It would be nice to find some setup which would intelligently measure the true torque output of an air impact wrench.

I'd LOVE to know the answer to THAT question!I've always wondered for years.How can we measure the torkue output of a zip gun?

Is there a dynamometer setup that is cheap enough for the average user?

Would it work to put a bolt in and then measure the foot pounds it takes to remove it?

Or would it be better to put a bolt in and measure the foot pounds it takes to move it a mm or so?

Has anyone ever measured the output of a zip gun before?

[navysnail]

well, if you turn that adjustment knob to different settings, you can feel the difference just holding the socket with your hand. those impact sockets are good for what your doing, the reason for using those is that an impact gun can rip apart and "explode" a normal socket.

if any of this has allready been said, i appologise lol

also, its not the sheer torque of an impact gun, but the rappid succession of powerfull impacts, thats why you dont strip as many bolts with an impact gun

also, i woudlnt use it to put bolts back on, i would use a torque wrench for that

[mixatonia]

Quote »i woudlnt use it to put bolts back on, i would use a torque wrench[/quote]From my experiense I see technicians put lug nots and the like on with the zip gun.

Then when they are done they torkue it up without moving the nut.

Are this process wrong? Or is it just another way of doing busness?

[DAEDALUS]

There are products called "torque sticks" that break torque at pre-set levels. The techs are fine with air tools if they're using these. However, the biggest problem I see is with techs who don't put the nuts on 3 full threads by hand first. You won't figure it out till your next tire rotation that they screwed up, and then you've got to deal with a broken/stripped lug.

[p00t]

[prophet] Listen to Daedalus! He speaks the truth! [/prophet]

[s13sr20chris]

i use air tools all day everyday.1)the torque rating means almost nothingsolution: just spend as much money as you can and you will be oki like ingersol rand and snap on impacts2)air pressure is good. i use at least 160psi at all times. our shops tire changer needs at least 145psi so we just crank the compressors up as high as they will go. works good.3)long hoses dont hurt but skinny slinky ones like my dumb boss recently installed do hurt the tools performance.4) you have to oil different holes on different guns because of their design. i have rebuilt them before and they usaully have separate chambers for the "turbine" side and the "hammer" side. i dont know the real names for them.5)some bolts need impact torque to get free and some need constant hernia inducing torque. the latter could be avoided by upgrading(which for me means going with a high dollar 3/4in gun) the amount of impact torque.