What sort of spec is required to run drills and die grinders properly? I'm always baffled by this, I currently have a 'hobby' clark hunter, 50L, 2.5hp, 8bar, 8.7CFM. Not a bad spec really, but its absolutely sh*te at running air drills or die grinders (tbh never bought it for that, it was for spraying which it does fine, but as always you end up wanting more).

But if you read the spec for your average air drill they're in the 6-7CFM range. So what am I missing? PSI's? 'Free Air'?

I have the chance of one of these units 2nd hand (price yet to be negotiated):

Clark SEV11C

But I dont want to bother if I'm just going to be disappointed again (no point replacing what I've got with something thats still not man enough). 2hp seems low, but 9CFM is slightly better and its 10bar. Also, will it be quieter being belt driven?

So really, what makes a good compressor?

For air tools you would need a min of 10bar 14cfm 150lt tank SE15 any less and it will always cutting in, but for extra £30 +vat i would go for SE19 10bar 18cfm 200lt tank and choice of 240/415v. If you have 3 phase check out local compressor companies who have ex demo / s/hand units.