[GMCnet] how much compressor do i need to bust loose BIG bolts
dave silva
Can someone explain to me what I need to know about air to break loose the big stuff on my coach?
I really want to know what are the minimums I can get away with to drive a substantial impact wrench.
I'm not a garage and I would not need to do this very often, and I'd be willing to wait for the head to build between bolts, (this ain't NASCAR)
So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
thanks
--
1972 Revcon 250- the other front wheel drive motorhome. http://www.davesilva.com/revcon
Parting out 1974 GMC 26- http://www.davesilva.com/gmc
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Rob Mueller
I did a Google search and came up with:
http://www.engineeringtoolbox.com/air-consumption-tools-d_847.html
http://www2.northerntool.com/air-compressor-buyers-guide.htm
http://catalogue.cp.com/e-catalogue/index_xmlhttp.asp?target=vs-impactwrench
es&BA=it
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
dave silva
THanks. That clears it up a little but I think i'm asking for real world applcation.
THose ratings assume you're going to work all day at that output. So if you need to use a 3/4 impact driver you need 8 CFM continuously, you're not expected to wait for the tank to load.
I'm thinking a cheap compressor might be a nice Christmas gift; for the occasional tire flling an brad driving. But will it be capable of busting loose tight nuts in confined spaces on some limited basis?
David H. Jarvis
I would think it depends on the impact gun. All the air pressure you can come up with won't help a weak impact gun.
--
"I've always been crazy, but it kept me from going insane"
Mr.erf ERFisher
torque them back on any way
gene
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
Matt Colie
hertfordnc wrote on Tue, 08 December 2009 13:28
> Can someone explain to me what I need to know about air to break loose the big stuff on my coach?
>
> I really want to know what are the minimums I can get away with to drive a substantial impact wrench.
>
> I'm not a garage and I would not need to do this very often, and I'd be willing to wait for the head to build between bolts, (this ain't NASCAR)
>
> So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
>
> thanks
Dave,
I have lots of air and a very good 1/2 impact.
It still takes a 3/4 ratchet with a piece of pipe to loosen steel wheel lugnuts and drive axle nuts.
Having air available is neat, but don't count on an impact until you have serious money in one. Little nut runners are neat to have - like a 3/6 palm wrench or air ratchet.
Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air)
SE Michigan
Charles Boyd
hertfordnc wrote on Tue, 08 December 2009 13:28
> Can someone explain to me what I need to know about air to break loose the big stuff on my coach?
>
> I really want to know what are the minimums I can get away with to drive a substantial impact wrench.
>
> I'm not a garage and I would not need to do this very often, and I'd be willing to wait for the head to build between bolts, (this ain't NASCAR)
>
> So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
>
> thanks
Sir: I have found the size of the air line matters. I use a 1/2" air line and the 1/2" impact works much better than with a 3/8" hose. No problem with wheel nuts.
--
C. Boyd
76 Crestmont by Midas
East Tennessee
Gary Casey
I think it depends on your intent. If you just need to break loose bolts that are difficult to do with a hand wrench, but don't necessarily need to spin multiple bolts out one right after the other (not NASCAR, as you said), then almost any compressor that can generate 100 psi would work. I used a 1/2-inch gun to loosen a crank bolt that was tightened to over 200 ft-lb and it took just a couple of "hits" with the wrench - almost no air was used. You need enough pressure and enough volume in the system to get the first few impacts, which are the ones that do the job. The most effective volume is that in the hose, so you don't even need a large tank. After one bolt is loosened you might have to wait for the pressure to build up. Even the coach compressor would be more than adequate and I'll bet you could break loose all 8 bolts of a wheel before it lost pressure. I think you need at least 80 psi and probably 100 would be plenty adequate.
Gary
________________________________
From: Rob Mueller <robmu...@iinet.net.au>
To: gmc...@temp.gmcnet.org
Sent: Tue, December 8, 2009 11:48:03 AM
Subject: Re: [GMCnet] how much compressor do i need to bust loose BIG bolts
Rob Mueller
I have one of these:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=2623
My compressor is a 5hp Sanborn (220 VAC 60HZ) that I've had for almost 20
years. It was NOT cheap.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist...@temp.gmcnet.org
[mailto:gmclist...@temp.gmcnet.org] On Behalf Of dave silva
Sent: Wednesday, 9 December 2009 7:26 AM
To: gmc...@temp.gmcnet.org
Subject: Re: [GMCnet] how much compressor do i need to bust loose BIG bolts
fred veenschoten
impacts can beat a nut to death before it lets go.
i agree about spending your bucks on a 3/4" drive breaker bar and a piece of pipe. it will loosen anything easily with nice quiet action.
--
Fred V
'77 Royale RB 455
P'cola, Fl
Dave King
I have a 39" Snap On bar (the one with no "business end". I have an end on it like a "Johnson Bar" but various heads are available. This thing does not bend or flex. I bought this to do the wheel nuts on my Dodge chassis motorhome that has flange style wheel nuts like the GMC but the nuts and studs are bigger and the owner's manual torque spec is crazy, like 250 to 400 ft/lbs. With this bar you can get your full weight a real 3 feet from the fastener.
DAVE KING
Terry Skinner
pipe, one each 1.25" and 7/8" impact type sockets. Those are the two
that are the killers. I have broken more 1/2" breaker bars around here
even though Snap on, Mack and Craftsman will replace them. It is just
the inconvenience of driving all the way to town to get a new one.
Remember, some people think that wheel lugs should be torqued to 250
lbs/ft. After you get them broken loose you can use any ol' air wrench
to spin them off or on.
"My story an sticking to it."..............Terry
--
Terry Skinner
253-686-2624
Roy. Washington
'76 GMC
Steven Ferguson
found that slightly tightening first, makes loosening much easier. If
you're using an impact, make sure you oil the air tool first, then run
in the direction that tightens, then reverse and most bolts and nuts
will break loose.
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
Craig Lechowicz
Dave wrote:
> So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
Dave, the short answer is 4 cubic feet per minute at 90 psi, if you believe all the specs, but more is always better. My experience has been the quality of the air wrench matters a lot more than the quality of the compressor. In it's day, my 25+ year old Ingersoll Rand 231 would take just about anything off, and now it struggles on the really rusty stuff. (Here's where having a neighbor with a newer and nicer Chicago Pneumatic comes in . . .) But, a lot of the discussion has been about reaching high constant torque (3/4 drive breaker bars with long handles . . . I bought a 5' piece of pipe to get my front axle nuts off, and I'm fat) That's typically not where I find an air impact most useful. You probably stand a 3 or 4 x better chance of successfully backing out a rusty exhaust manifold bolt with an air wrench than you do with a long handled tool, as the impact action is much less likely to twist it off. And for that, a one or two hp compressor is probably fine, but a
"name brand" air wrench is much more successful than a $39 one that comes with the compressor.
Just what my experience has been,
Craig
--
Craig Lechowicz
'77 Kingsley, Waterford, MI
Ken Burton
I have just about sworn off of impact wrenches. I primarily use them for a speed wrench. I also use them at lower torques settings to loosen stuck (usually rusted) bolts after a thorough soaking for days with Kroil.
As speed wrench example, on wheel nuts I break the nuts loose with a long bar and a socket. Then I spin them off with an impact (speed) wrench. I spin them back on with a quick pull on the trigger of the impact and then finish with an appropriate torque wrench.
On stuck bolts, like exhaust manifold bolts, I soak the bolts for several days with Kroil and loosen them with a lower power 3/8" impact. The jerking motion helps to break them loose, without twisting / breaking them off. I never exceed the torque rating of the bolt. Occasionally on a really stuck I use some heat from a flame wrench to assist the Kroil.
For the above reasons I question the need for a large impact wrench.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Wayne E LaMothe
My two cents. To me the biggest part of the equation is the impact gun. Mine is rated for 450lbs and really does not do a lot. I needed to break loose an axle nut on the old Wagoneer and it would not budge it. Nor would a 2ft breaker bar with 4ft of pipe on it. At that point my compressor developed a leak. My Brother-in-Law came over with his 1000ftlbs impact wrench and spun that nut off first try using a Dewalt contractor compressor designed for an air nailer. It is all in how the gun uses the air supplied to it. More air cfm will not increase the torque of a gun.
YMMV
--
Wayne and Lisa,
Bolton Landing, NY,
Patriot Guard Rider,
Standing for those who stood for us.
Steven Ferguson
axle nuts on my GMC by generating 60 ft lbs of torque with a breaker
bar..........attached to my torque multiplier. They are expensive but
if you watch EBay, every now and then one shows up for a very fair
price compared to the new price.
With it I can easily generate 500 ft lbs of torque necessary to set
pinion depth/crush a crush collar. Handy device.
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
Don Jeffers
For breaking loose the drive axle nuts (A big nut on a big bolt):
1. At NAPA we simply bought the correct size 3/4 inch drive six point socket, a long 3/4 inch drive handle, and
2. At Lowes we bought a three feet long piece of galvanized gas pipe of an inside diameter just to slip over the socket drive handle and a couple of inches of PVC tubing that I squeezed into each end of the galvanized pipe.
The Lowes items we then made into a "Johnson Bar" with the PVC inserts to prevent scarring the 3/4 inch drive handle. Works great for the axle nuts, they come loose very easily.
When not in use we just slip the drive handle with the socket attached into the pipe and they store in the pod with a minimum of volume.
Air Pressure Needed:
As for how much air do you need to drive an impact gun? Possibly none. We have both air impacts and electric impacts. The electrics are so convenient to use that we reach for the electric first, especially if our air compressor is not fired up.
Don & Susan Jeffers
78 Eleganze II
mills
but that is only based on 30 years of using impacts from 1/4" square
drives to 1 1/8" spline drives. Of course if the wrench has not been
oiled regularly and overhauled when due all bets are off.
--
Jim Mills
Greeley, CO
1973 CanyonLands 260 TZE-063V100731(under renovation)
1973 Glacier 230 TZE-033V101993
On Wed, 2009-12-09 at 09:23 -0600, Wayne E LaMothe wrote:
>
> My two cents. To me the biggest part of the equation is the impact gun. Mine is rated for 450lbs and really does not do a lot. I needed to break loose an axle nut on the old Wagoneer and it would not budge it. Nor would a 2ft breaker bar with 4ft of pipe on it. At that point my compressor developed a leak. My Brother-in-Law came over with his 1000ftlbs impact wrench and spun that nut off first try using a Dewalt contractor compressor designed for an air nailer. It is all in how the gun uses the air supplied to it. More air cfm will not increase the torque of a gun.
>
> YMMV
_______________________________________________
Gary Casey
depend on there being as little pressure drop in the line as possible. So, you need a short, large diameter line (just avoid the little 3/8 plastic lines) and a modest tank. I could pump the tank up with a bicycle pump and it would work just as well for the first bolt. Just trying to save the original questioner some money.
Gary Casey
Elbert, CO
'73 23 under "renovation", er, "refurbishment"
________________________________
From: mills <mi...@bmi.net>
To: gmc...@temp.gmcnet.org
Sent: Wed, December 9, 2009 11:58:08 AM
Subject: Re: [GMCnet] how much compressor do i need to bust loose BIG bolts
Reduce the CFM below what is specified will reduce the available torque,
dave silva
Well I certainly got my answer. This really is an amazing board.
Conclusion: I may add a compressor to my inventory if i can also afford a high quality impact wrench. A cheap wrench is more useless than a cheap compressor.
Imagine what i would have gone through to gather the data for that answer without this board.
thanks
--
1972 Revcon 250- the other front wheel drive motorhome. http://www.davesilva.com/revcon
Parting out 1974 GMC 26- http://www.davesilva.com/gmc
Keith V
You are correct.
I got a decent craftsman impact wrench. It was rated at like 250? ft/lbs. It couldn't loosen the lug nuts on my car, 85 ft/lbs! The salesman claimed my compressor wasn't big enough...
B.S., the compressor never came on. 120psi from a 20 gallon tank, if it isn't loose in the first 10 seconds it aint coming off.
I FINALLY traded it for a nice ingersol rand, 650ft/lbs rated or something silly. Same compressor and it spins those lug nuts off like nothing.
It even took the axle nut off of my GMC, and it's only a 1/2 drive wrench.
If I had it to do over I'd buy one with at least 800 ft/lbs and a good one.
hertfordnc wrote on Thu, 10 December 2009 06:05
> Well I certainly got my answer. This really is an amazing board.
>
> Conclusion: I may add a compressor to my inventory if i can also afford a high quality impact wrench. A cheap wrench is more useless than a cheap compressor.
>
> Imagine what i would have gone through to gather the data for that answer without this board.
>
> thanks
--
Keith
69 Vette
29 Dodge
75 Royale GMC
Mark Scoble
Would anyone be interested in a 3/4" 120VAC impact wrench? I bought two from a government surplus sale and the maintenance tags simply said "needs new switch", which is a simple on-off affair used in many devices and I found at a local h/w store for $10. These were made by Boston Pneumatics (even though they run on AC power) and cost over $3,600 each when new. I paid $250 each (as-is0 so I could change my own tires on the GMC.
Any interested parties, e-mail my personal address please:
mailto:worl...@aol.com
--
Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and undergoing complete renovation at the GMC Co-Op
Roger Warner
I had to look for an air compressor a few months back, there's this buying guide I found pretty helpful:
http://www.thomasnet.com/articles/machinery-tools-supplies/Buying-Guide-Compressor...
And you can source a supplier too, I personally didn't, but if your trying to find a company, it'll probably be helpful: http://www.thomasnet.com/products/air-compressors-17092800-1.html