Air compressors

Aug 24, 2007 21 Replies

Hi all,



Might be inviting a lot of chuckles here but....



Now I'm getting more experienced (yes, ha ha) and that I saw a SIP 25L compressor (as per eBay item 170142156209) in my local Costco for £99 inc VAT with a 10 piece tool kit (pressure washer, a couple of spray type devices, vacuum, tyre inflater etc...) I'm now wondering whether it might be worth getting and getting an impact wrench from somewhere.



This is mainly because I'm a little tired of rolling around on my back trying to apply a breaker bar to stubborn bolts when the car is on axle stands and you've got 20 degrees of swing for the breaker bar.



Questions...



The air specs are:



# Air displacement : 8.0 CFM (227 L/min) # Max free air delivery : 5.2 CFM (147 L/min) # Free air delivery : 4.4 CFM (125 L/min)



Now what is the difference between those three? :) Peak and continuous?



How much will an impact wrench use? I've seen some advertised as 4 CFM and some as 15 CFM. Also do they / can they have torque limiters for doing stuff up that'll stop it applying more than about 20-30Nm? I've not seen that advertised as a feature anywhere, of course if they don't do that then I won't use one for doing stuff up!



I'm sure I'll use the other tools too, patio furniture needs respraying and the Fiesta's engine bay could do with degreasing. Plus my cheapy electric pressure washer just broke down - I know an air powered one won't be as powerful.



Seems like a good buy? :)



Thanks again,



Peter.


Any compressor with a tank will do for domestic stuff, air wrenches only run for a few seconds, so compressor capacity is fairly unimportant, spraying is a different matter entirely, as is using a sander.

Torque limitation on an air wrench is very hard as there are too many variables. Whizz up wheel nuts with an air wrench but check them with a torque wrench or bar.

Aldo/lidl often have cheap air tools that are perfectly adequate. Get their weekly special email and keep an eye out.

Buying from Costco is a good idea as you could always return it if you find it isn't man enough, then you could buy the big compressor they have !!!

Mrcheerful

Receiver tank is a bit piss poor as most of them are at this end of the market. Only 25 litres. That means you'll be spending a lot of time stopping and waiting for the system to repressurise if you're using airtools a lot.

If you really only want it for that - but are inventing other uses to justify the purchase ;-) - get a cordless impact drill driver instead for about the same price. Very useful for DIY too.

OK, thanks :)

I'm not sure that the bigger air compressor will even fit in the Fiesta :) Also the wife may moan about the cost and space usage!

Peter.

Yeah, I know.. That's not much of an issue however, storage space is quite limited which is a more important consideration, I'm pushing it as it is :)

Thanks,

Peter.

Inventing other uses? Perish the thought :)

I considered that but isn't it that case that one of those will have recoil whereas the air powered wrench won't?

Thanks,

Peter.

Asa long as you're aware of the limitations, give it a go.

Oh. I thought that as they worked by slowing the incoming air down to produce torque the opposite force is the driven surface acting on the incoming air, not on the wrench itself. In an electric powered device the opposite force the magnets in the motor trying to move the other way to the coil hence trying to turn the whole device. I've gone wrong somewhere though given that both devices are usable despite having short handles and producing upwards of 200Nm :)

You can feel it kicking under heavy load but quite manageable. Dunno about air ones - I don't have a garage so can't really have a compressor. So have to have the electric alternatives.

They can tighten bolts that much, but they do it by smacking into them rather than tightening them in a conventional manner. It's akin to hitting the end of a short spanner with a hammer very quickly lots and lots of times.

The primary benefit is speed. You don't get the amount of torque that some would have you believe from a windy gun. I've worked on lots of cars where it wouldn't undo the wheel nuts, so I've undone them with a 2ft length of pipe over the T bar. It makes a mockery of the claims of "some numpty did them up with an air gun and I can't undo them" IME, that's far more likely to be because they haven't been undone until the pads started scraping or it finally failed a test.

I set the gun on 3 for doing them up and on 4 for undoing and I've had no trouble.

Steve

I have found this article useful, in particular, this page: "Air Compressors Buyer's Guide" (Page 3)

formatting link
down the page, you will read: "The rule of thumb you can use todetermine your approximate needs is that 1 HP should produce 4 to 5 CFM."To me, that's the single most important piece of information! But first,you have to find your impact wrench, the most demanding tool in yourintended collection, and look up its specifications.

Also useful is this page. They are from my useful info collection/databank! "Compressor Choice"

formatting link
HTH.

They've both got a bit of recoil, but suffeciently little it's not an issue. If you want a lot of torque though the air powered ones are far far cheaper.

You just need a bigger rattle gun:-) Although they're useless for undoing anything springy.

That's the case with most air tools. Provided you first have the compressor and of course somewhere to keep it. I have to work in the street on cars. My workshop is on the first floor. ;-)

I bought one of the 12v electric ones, it fell apart. The impact hammer split in two. I now have an air-powered one, and it is more powerful (half inch drive) and is still going strong.

Do you mean one of those 'unbranded' cheap types that plug into the car battery or a *cordless* tool like the Bosch currently on sale in B&Q (and elsewhere?

A decent make cordless impact drill driver is designed for long and heavy service life. Anything else would be pointless.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required