Compressors And Air Tools

[Fossilface]

Are there any air tools experts in here that can assist me please?

I bought a compressor from Aldi the other day (no Aldi comments please lol) with the intention of running a few air tools on it.
I bought a die grinder today which has a consumption of 8CFM and recommended pressure of 90 psi but the compressor is really struggling to run it inspite of the compressor having a max air flow of 9.5 CFM and a max pressure of 120 psi.
The tank capacity is 24 litres and it is 2.5hp.

When I say really struggling, I mean I can very easily stop it turning with my hand.
Have I simply bought an optimistically rated crap compressor?
Any help gratefully accepted

[Fossilface]

doogz said:

Stupid question, but i have no idea how mechanically competant you are. Have you turned the regulator up full? The pressure in the tank isn't necessarily the output pressure, you should have a second gauge and a regulator to control it?

Yeah, the regulator is on full.

This is it, if it helps.

http://www.aldi.co.uk/uk/html/offers/special_buys3...

[Mermaid]

Fossilface said:

Yeah, the regulator is on full.

Not a hijack (really) but what make & spec would be a good compressor for domestic use?

[andym1603]

It is possible you have been optimistic in expecting to run air tools from a small compressor.
This unit may only be suitable for a tyre inflator and an air blowgun.
When people buy compressors they look at the cfm quoted and are of the opinion that it will
power impact wrenches and sprayguns etc.
When compressors are advertised the sellers, unless they are in that business, always quote the
cfm produced. Unfortunately that number may as well be next weeks winning lottery numbers as it
mean diddly squat. What they should be advertising is the free air delivered (fad), which is the usable
air from that specific machine. The fad is more likely to be a lot less than the cfm produced.
Hope this helps to explain your situation.

Andy..

[Fossilface]

andym1603 said:

It is possible you have been optimistic in expecting to run air tools from a small compressor.
This unit may only be suitable for a tyre inflator and an air blowgun.
When people buy compressors they look at the cfm quoted and are of the opinion that it will
power impact wrenches and sprayguns etc.
When compressors are advertised the sellers, unless they are in that business, always quote the
cfm produced. Unfortunately that number may as well be next weeks winning lottery numbers as it
mean diddly squat. What they should be advertising is the free air delivered (fad), which is the usable
air from that specific machine. The fad is more likely to be a lot less than the cfm produced.
Hope this helps to explain your situation.

Andy..

Hi Andy, thanks for that.
As I suspected, I have bought an air gun lol.
Oh well.
If this one isn't upto the job I may as well take it back.

As already asked, what would be an appropriate compressor to run things like a die grinder from?

Thanks.

Edited by Fossilface on Tuesday 15th March 18:49

[SplatSpeed]

this is the min I would consider

http://cgi.ebay.co.uk/Air-Compressor-3HP-50L-50-lt...

[anonymous-user]

I agree with Splatspeed, I've got a Chinese cheap domestic compressor, 3hp 50 Liter, will run a wheel gun, drill, air wrench and a die grinder everything I want, but it struggles with a 4in grinnder, but start with afull tank and allowing for stops while you have a 'look at what you've done' it works fine even with that.
Great tool, you wonder how you managed without it, but as said on here a few weeks ago they become addictive.

[dudleybloke]

with compressers i'v always found its best to find the one you think you need and then buy the next size up.

[normalbloke]

SplatSpeed said:

this is the min I would consider

http://cgi.ebay.co.uk/Air-Compressor-3HP-50L-50-lt...

Be aware that direct drive compressors( as this is) are generally very noisy compared to belt driven items.

[cpas]

As AndyM said, the figures given are the theoretical cfm worked out from the cylinder or diaphragm size and the oscillation speed. This figure is theoretical as, once under any load, the actual free air delivery will be reduced to about 2/3 of the theoretical value. I think Machine Mart quote both figures.

[pikeyboy]

As others have said I think you,re being a bit ambitious trying to run a die grinder from a small compressor. I've had 3hp single phase with a 150ltr tank for years now. I cant remember the CFM but it powers my devilbis JGA spray gun OK and like wise my die grinder no probs. I think with these sort of things, biggest is often best.

[Fossilface]

Yeah, I now realise that I can use it for things like an air gun and that's about it.
I've decided to keep it for now as one of my major limitations is space and this one fits in a corner I have spare, but a larger one wouldn't.
With my project car in the garage. I only have a few feet spare around it.

Hopefully at some point the garage will get bigger, a bigger compressor will be acquired and this little baby will go on E-bay, hopefully only losing me about £30 to £40.

[dienamic]

I can recommend these http://www.halfords.com/webapp/wcs/stores/servlet/...
Have run one at work for 3 years without a problem. Easliy as good as our £3k Sealey.

[normalbloke]

dienamic said:

I can recommend these http://www.halfords.com/webapp/wcs/stores/servlet/...
Have run one at work for 3 years without a problem. Easliy as good as our £3k Sealey.

I'd seriously look at buying a decent second hand single phase belt driven unit. I'd choose a decent branded second hand unit over a cheapo smaller direct drive unit all day long.The other bonus with a branded unit is that you will probably be able to buy parts for it long after it is dis-continued.

[buzzer]

I also have one of the Aldi units from the last time they were on sale. I think a big problem for home use is the size of the tank. I have a large calor gas cylinder at the back of may garage (outside with a pipe through the wall) which acts a a bigger tank. this makes a HUGE difference to how the compressor performs. I can run a 4 CFM die grinder easily now. With the standard tank it struggled...

Incidentally, I got the calor cylinder from my local tip... slipped the guy £5 and he gave me a big one (oh er!)

[foz01]

What's considered a good brand to buy second hand.

Would sandblasting a set of alloys be beyond the capability of most stuff under 200 quid?

[ndg]

I have small pressurised sandblasting setup, running off a 4hp 50ltr compressor(it's a dodgy chinese one so probably 3hp really!). From memory it's a 14cfm one (probably not F.A.D.). When blasting it runs flat out 100% of the time, so I think you would struggle with anything smaller for blasting. I did a set of rims two weeks ago, face and lip only, and they took about 4 hours.

N.

[Super Slo Mo]

buzzer said:

I also have one of the Aldi units from the last time they were on sale. I think a big problem for home use is the size of the tank. I have a large calor gas cylinder at the back of may garage (outside with a pipe through the wall) which acts a a bigger tank. this makes a HUGE difference to how the compressor performs. I can run a 4 CFM die grinder easily now. With the standard tank it struggled...

Incidentally, I got the calor cylinder from my local tip... slipped the guy £5 and he gave me a big one (oh er!)

I don't wish to knock your ingenuity, which is impressive, but is this not a little dangerous?

Do you know what safe pressure the gas cylinder can handle? I'd be a little nervous of it to be honest, but then it's not my setup, and you may of course know exactly what you're doing.

[buzzer]

Super Slo Mo said:

buzzer said:

I also have one of the Aldi units from the last time they were on sale. I think a big problem for home use is the size of the tank. I have a large calor gas cylinder at the back of may garage (outside with a pipe through the wall) which acts a a bigger tank. this makes a HUGE difference to how the compressor performs. I can run a 4 CFM die grinder easily now. With the standard tank it struggled...

Incidentally, I got the calor cylinder from my local tip... slipped the guy £5 and he gave me a big one (oh er!)

I don't wish to knock your ingenuity, which is impressive, but is this not a little dangerous?

Do you know what safe pressure the gas cylinder can handle? I'd be a little nervous of it to be honest, but then it's not my setup, and you may of course know exactly what you're doing.

The bottles are manufactured to DOT specs. Working pressure 240 psi, test pressure 480 psi, design, burst pressure 960 psi. Depending upon the ambient temperature, propane in a tank is around 110 - 130 psi. Most Single stage, home-use compressed air is generally not more than 130 psi. I have been using mine for many years with an old compressor. However, I am always a bit nervous around compressed air tanks, especially the big ones. I have a very big and old compressor in the garage which lives behind a 25mm plywood screen as the tank on it is very old and shows signs of rusting inside…

They don’t put strict regulations on compressed air tanks for nothing! Having said that, I was once speaking to a BSI inspector whose job it was to inspect tanks. He said he had been to quite a few that had burst and although they went with a bang, all the ones he had seen has just split along the bottom welded seam. That’s why the seam is always at the bottom apparently.

you are right to question it though, you cant be too careful with tanks!

Edited by buzzer on Sunday 20th March 22:09

[Super Slo Mo]

buzzer said:

The bottles are manufactured to DOT specs. Working pressure 240 psi, test pressure 480 psi, design, burst pressure 960 psi. Depending upon the ambient temperature, propane in a tank is around 110 - 130 psi. Most Single stage, home-use compressed air is generally not more than 130 psi. I have been using mine for many years with an old compressor. However, I am always a bit nervous around compressed air tanks, especially the big ones. I have a very big and old compressor in the garage which lives behind a 25mm plywood screen as the tank on it is very old and shows signs of rusting inside…

They don’t put strict regulations on compressed air tanks for nothing! Having said that, I was once speaking to a BSI inspector whose job it was to inspect tanks. He said he had been to quite a few that had burst and although they went with a bang, all the ones he had seen has just split along the bottom welded seam. That’s why the seam is always at the bottom apparently.

you are right to question it though, you cant be too careful with tanks!

Edited by buzzer on Sunday 20th March 22:09

Thanks for that. It's interesting info, I suspected the gas tank would have a fairly high factor of safety, but I've never heard of anyone using them for compressed air before. You have me thinking now, although I yet to purchase even a compressor (in fact, my garage isn't fully complete as we speak).