CableSrv Posted March 12, 2007 Share Posted March 12, 2007 Over the weekend I went to sears and put down 300 bucks on a 26 gallon 2hp 6.4cfm at 90psi craftsman compressor. I'm looking for some new tools to use in my garage for repairing my rusted 240z. However I'm getting lost really on the difference. the tools I'm looking for are 3in cut off and a angle die grinder and possibly a sander. I understand the cfm and that if I get a tool that is rated higher in cfm than my compressor it will have a recharge time, as it will use the tank then have to wait for the compressor to rebuild charge, where as I can get a tool with a cfm rated to my compressor and the compressor can just run the tool. but then i'm confused. whats the difference between a cutoff rated at 20,000 rpm at 4cfm and one rated at 20,000 rpm at 14cfm ? Does the higher cfm make it cut easier ? through thicker metals ? will a 4cfm fail me on what I need it to do ? Most of my repair will be cutting out rusted spots and welding in new patches and hopefully sanding the car down to the metal and doing some basic body work, nothing to extensive or to the point of doing it over long periods. It's the reason I put down 300 for that compressor. I didn't think that I'd be using it for 8+ hours a day more like 1-2 hours if anything. should I get the cheap 4-6cfm tools ? will they support me on what I need to do or was I stupid in thinking I could do patch work with this compressor ? Quote Link to comment Share on other sites More sharing options...
naviathan Posted March 12, 2007 Share Posted March 12, 2007 You can't really tell by the consuption rating of the tool how good it will be, but typically the lower the cfm the less powerfull the tool. However just because it has a high cfm rating doesn't mean it's any good either. Some cheap china made tools have a huge cfm rating, but they're not built to maximize the air it's using. Buy quality tools, especially when it comes to air tools. 26 gallons @ 6.4cfm is a small compressor and isn't going to be able to handle a sander, a cutoff or a die grinder. All three of those tools use a lot of air. Even on my 60 gallon @ 12.5 cfm my compressor kicks in after only a short time using my cutoff or my sander. The die grinder is really bad if I have it at full speed. You will need a better compressor for the work you want to do. Quote Link to comment Share on other sites More sharing options...
NCchris Posted March 12, 2007 Share Posted March 12, 2007 26 gallons @ 6.4cfm is a small compressor and isn't going to be able to handle a sander, a cutoff or a die grinder. All three of those tools use a lot of air. Even on my 60 gallon @ 12.5 cfm my compressor kicks in after only a short time using my cutoff or my sander. The die grinder is really bad if I have it at full speed. You will need a better compressor for the work you want to do. Times two! I have the 26 gallon 5 or so HP. It will only run my die gringer for a few sec before the compressor cuts on and then I need to wait on it to get back to full charge. Go bigger if you possibly can! Air tools use lots of air. Bigger is better! chris Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 12, 2007 Share Posted March 12, 2007 I kind of agree with the above. Bigger is definitely better, there is no doubt about that. However, I've gotten a hell of a lot of projects accomplished on my car with a 5hp 20 gallon 110V oilless compressor. It is certainly not ideal, it is LOUD, and it runs almost constantly when I'm heavy into grinding or cutting on a project, but it has given me the capability to do jobs that I simply wouldn't otherwise have been able to do. But I would not spend $100 on a Snap-On die grinder. I buy most of my air tools (except impact guns) from Harbor Freight and the only issue I've had is the shaft on the die grinders are usually not perfectly straight, which is kind of problematic for porting and polishing heads. Other than that, if it spins the cutoff wheel it's going to cut. It might have to be restarted a couple times when you stall it out on a heavy cut, but that's more than worth the extra $90 expense for the Snap-On or equivalent tool in my opinion. I think the sander is going to be a real problem with a compressor of that size. I bought an electric DA sander for my project. But the cutoff wheel and die grinder will work, although the compressor will run from about 15 seconds after you start the tool. The real question is how much $$$ do you have to put into a compressor. Buy as much as you can afford, and if you can't afford much, then use what you have to its fullest potential. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 13, 2007 Share Posted March 13, 2007 I bought a couple of Campbell Hausfield tools and some Husky tools. The Husky air tools from Home Depot are both working rather well. The CH stuff is OK but definitely like the Husky stuff better. Also have a Sears impact driver that is not what I would like it to be. And like the others said, you really need a 220V compressor. A true 5 HP continuous motor will need 22 amps at 220V. My die grinders will run my compressor continuously, but I never fall below 90 PSI or so. Haven't tried a larger sander. All the rest of the tools barely tax the compressor. What I really need to do next is get a second air tank so I can get the moisture out of my air lines (something Tony D recommended). I have a separator in the line, but it doesn't seem to keep the condensate out of the copper air lines I ran about the garage. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted March 13, 2007 Share Posted March 13, 2007 Since we are talking about compressors, how do you guys feel about these two? Will this first one be enough or should i go ahead and get the 2nd, bigger one? http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_158284_158284 http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_211720_211720 Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted March 13, 2007 Share Posted March 13, 2007 i bought one of the hd husky compressors a while back. 30 gal 5 hp i think. runs constantly while i am using a die grinder or media blaster. i have an air da sander that killes the compressor, so like john i bought an electric one from sears. i figure i do not have to wait for it to come up to full strength to sand. i think a dual stage would kick a$$ but do not have the $$$. i have learned to have patience with what i have. blast for a while then find something else to work on. kind of sucks but it is what it is. jimbo Quote Link to comment Share on other sites More sharing options...
Cruez Posted March 13, 2007 Share Posted March 13, 2007 Take my word of advice..... if you are going to be using it quite a bit and are going to run DA sanders, die grinders or blasting equipment.. Get the one with the most CFM you can afford... I already have upgraded after a year and a half... BTW... anyone wanna buy a 1 1/2 year old compressor Got my (big) new one wired (finally) Quote Link to comment Share on other sites More sharing options...
CableSrv Posted March 14, 2007 Author Share Posted March 14, 2007 so sanding is really out of the question then with this compressor. As for the die grinding.. yea I don't see myself doing more than 2 mins worth of grinding at once it would be way intermittent. The only reason for die grinding would be cleaning up my welds as I finish one part up at a time. this week i'm ordering my welder which I've decided to go with the miller matic 140 with auto set. I think it will be a good first welder for a learner no ? Quote Link to comment Share on other sites More sharing options...
Metallicar Posted March 17, 2007 Share Posted March 17, 2007 Even though I now have a 5hp compressor with 60 gallons of storage, I still preffer to use my 4 1/2" grinder with 36 grit discs for grinding welds. I also use it most with cutoff wheels, not the air tool. I also picked up a Rotozip, with all of the attachments on sale at Home Despot. It came with the angle grinder attachment that uses 3" wheels. I also bought the flex tool (like a dremel) attachment for it. It works very well for small stuff like port and polish. I also highly recommend adding more air tank capacity. Over the years, I have at times, used old water tanks, old propane tanks, freon bottles, and once I used an old commercial water heater. One summer, I used an old chiller barrel, while I was waiting for the price of scrap to go up. TonyD did a write up about air consumption and storage a few months ago about this. It's another good read, by The Man. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted March 17, 2007 Share Posted March 17, 2007 I've got a 5hp 13.8 cfm @ 135 psi compressor with a 60 gallon tank, it doesn't keep up with the die grinder, but it works for quite awhile before it has to catch up. Also I turned my compressor settings up to 145 psi for the high cutoff and 120psi for the low cut in. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted March 17, 2007 Share Posted March 17, 2007 I've got a 5hp 13.8 cfm @ 135 psi compressor with a 60 gallon tank, it doesn't keep up with the die grinder, but it works for quite awhile before it has to catch up. Also I turned my compressor settings up to 145 psi for the high cutoff and 120psi for the low cut in. So how much did this help? I've thought about doing the same thing with mine. Quote Link to comment Share on other sites More sharing options...
lbhsbZ Posted March 17, 2007 Share Posted March 17, 2007 Well, seeing as how you already bought the compressor, this is what I think you should do now. Go down to harbor freight and get an air cutoff tool and a couple of those $7 die grinders. I've got 10 of the die grinders. They're so cheap, I leave a different bit in each one of them. while you're there, pick up a couple of those orange electric angle grinders. Use one with a flap wheel for cleaning and prepping metal, and use the other one with a cutoff disk for your heavy cutting. If you want to do sanding, get a orbital electric sander. Save the compressor for impacts, air ratchets, minor cutting and grinding, etc. Unless you are a smoker and drinker, the breaks you have to take every 5 minutes to let the compressor fill back up will start to piss you off quick. Quote Link to comment Share on other sites More sharing options...
240zV8 Posted March 17, 2007 Share Posted March 17, 2007 I have a 26 gal 2hp(running) belt driven oil lubed compressor, it can be wired for 220v, or 110v. It's great for impact guns, ratchet wrench, paint gun. But when I use my die grinder or sander, the compressor kicks on after about 15 seconds, and if you use the sander or ginder constantly the compressor will run the whole time, I haven't wired it for 220v, but i assume it would run better on that.. Thats why I bought a electric orbital sander, and a electric 4 1/2" ginder, there alot better and quieter for my use. The compressor draws more amps when it's running constantly, than running a electric tool, so theres no benefits with a smaller compressor really, unless ur painting, or using air wrenches. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 19, 2007 Share Posted March 19, 2007 Urgh... A compressor running continually at the pressure it needs to drive the tools is more efficient than one that pupst over the required pressure, shuts off, then restarts to pump up at some lower pressure. In air, storage storage storage is the key! The more storage capacity you have, the less horsepower you will need for impulse loads. Air tools rating? Trash and marketing hype. See if you can find an Ingersoll Rand Air Tool Catalog---they are one of the manufacturers that shows the "real" consumption of an air tool when in actual 100% duty----general rule of thumb, 2 to 3X what the 'rated CFM' of most manufacturer's ratings say! As I'm sure John C will say soon enough: Buy a used compressor, and industrial one that some local mom and pop compressor house took in on trade. Convert the motor to 220V single phase, and be set for life with a 5HP compresson made of good old American Cast iron sitting on a 120 gallon tank. Use a regulator AT the tank, don't run the tools on tank pressure, you're wasting air. What am I doing right now, besides shirking my paperwork duties at work? Supervising the Emergency Overhaul of an 8000HP Joy 4MSG12 Air Compressor for an Air Products 290Ton Per Day Air Separation Facility. Every day they are down it costs them $200,000 in lost production. Not a real big compressor, but big enough. The low speed rotating assembly weighs 686#, and spins at 12,800rpm. If you want specific questions answered, PM me, and I'll try to do my best to help you out. Air is my business...Air Solutions, more specifically. Damn, I sound like a salesman now... LOL Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 19, 2007 Share Posted March 19, 2007 220V, 120 gallon tank/7hp two stage Speedaire on@125psi/off@175psi. I can run a bayflex sander (7" disc) continually until the compressor kicks and it will run, catch up and shut off again without letting up on the bayflex. I built it 15 years ago for about $900. You can't have enough tank volume and compressor size. I learned that by burning up two much smaller compressors years before. Quote Link to comment Share on other sites More sharing options...
MrFancypants Posted March 19, 2007 Share Posted March 19, 2007 Nobody has added this point yet, so I'll chime in... check the dBA rating of the tools you are looking at. Cheap air tools will be inefficient and LOUD. Spend a little more and save your ears. A good example is my Ingersoll Rand reactionless air ratchet (IR111). It's at least 3 dB quieter than your average ratchet (i.e. half as loud), and spins 300 rpm instead of the usual 150 or so of a cheaper ratchet with the same torque. In other words, it's gobs more efficient and is easy on your ears. Sound is just wasted power! http://www.irtools.com/IS/modelComp_full.asp?item=3039 Also shop for weight. I have an IR impact gun that weighs 4.5 lb -- makes a huge difference when youre under the car! - Greg - Quote Link to comment Share on other sites More sharing options...
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