3HP and 2.5HP have same CFM

[the snooper]

are the compressors you are looking at belt drive or direct drive ? the direct drive are very noisy belt drive are far better machines

 

[the snooper]

Yes, it means chassis work unfortunately !

for 3mm stick with the plasma

 

[v8burbling]

Awesome answers everyone thanks. Yes, Snooper it will be a direct drive. The belt drives seem to be a lot more expensive. I saw one 3HP belt drive and it weighed 80kg ! I am looking at £100 ish and those machines are more like £400.

 

[Maker]

Awesome answers everyone thanks. Yes, Snooper it will be a direct drive. The belt drives seem to be a lot more expensive. I saw one 3HP belt drive and it weighed 80kg ! I am looking at £100 ish and those machines are more like £400.

I'd bet they're at least 4 times better too. Could you get a nice big second hand one?

 

[the snooper]

Awesome answers everyone thanks. Yes, Snooper it will be a direct drive. The belt drives seem to be a lot more expensive. I saw one 3HP belt drive and it weighed 80kg ! I am looking at £100 ish and those machines are more like £400.

yes they are more expensive but better, start thinking along the lines of building a simple cover to kill the noise, they drive you mad

 

[v8burbling]

Yes I know you're talking sense guys. I'm just wanting to get started. I have a few days off after Easter and want to get some serious work done on the car restoration - I don't get the chance very often. I'd love to have the time to buy an old broken one cheap and fix it, install a 16A supply etc but that's not going to get the car fixed. I'm sure I'll be wishing I'd taken your advice in a month or two. Perhaps I will sell it then and upgrade as you recommend. Thanks again. I appreciate all your comments. This is a fantastic web forum.

 

[Paul G]

To be honest my tool of choice would be a 115mm Makita (or Bosch) angle grinder
and a box of Smith & Arrow 1mm cutting discs.


If you use plasma then you'll need to clean up with the grinder anyway so cut out the middle man.

Paul G

 

[rtbcomp]

Aldi sometimes have 2.5hp ones in at £60 - two of those will get you started. They're direct drive though but do come with a 3 year warranty.

 

[Wallace]

The direct drive are very noisy and drive you mad. What air tools are you looking to use? You might find it more cost effective to buy electric equivalents. I picked up a cheap 75mm cutoff tool a while back to get into couple of places a 4.5" grinder can't and it slaughters my Clarke SE16C 150 even regulated to 90psi. I dread to think what the running costs are for a single 12" cut!

 

[normspanners]

The link for the 3hp one says "input power: 1500W", 1.5 kW is 2 hp, not 3. I don't know how the output power has been calculated but that's closer to 1 1/4HP. I don't think I'd bother with one of these.

Well done maker thats what I thought 7.5 cfm ??especially only running up to 115psi, which is very low, my compressor kicks back in at higher pressure than that.
Maker you sure your 15??.
I'm well impressed

 

[v8burbling]

Well done maker thats what I thought 7.5 cfm ??especially only running up to 115psi, which is very low, my compressor kicks back in at higher pressure than that.
Maker you sure your 15??.
I'm well impressed

Indeed ! I checked with the supplier (who checked with the "Warehouse Manager") and they've come back confirming it is a 3HP machine as they have other ads for 2HP machines. I have asked them to confirm the input/output power, displacement and pressure figures.

 

[normspanners]

3 hp should be 2250 ish W
http://www.engineeringtoolbox.com/horsepower-compressed-air-d_1363.html to give you an idea

 

[v8burbling]

3 hp should be 2250 ish W
http://www.engineeringtoolbox.com/horsepower-compressed-air-d_1363.html to give you an idea

Ah yes, the internet of everything ! One of my graduate engineers googled the conversion between metres and area the other day to work out the area of our office !

Admittedly, the HP-electric power conversion requires knowledge of the correct coefficient and the link you provided is even better so justified use Sir ! Thanks.

 

[rtbcomp]

As a matter of interest the calculator that comes with Windows 7 has unit conversions built in.

 

[v8burbling]

So here's two pics of the spec plate off the air compressor. It does look like 3HP as they said and the power is 6.5x220=1.43kW
Any ideas ?

 

[Maker]

I'm still not convinced, it says the current is 6.5A which means the power cannot be more than 1560 watts, ~2HP but it will be less than because of energy lost to inefficiencies. According to this page, a 6.5 amp motor is going to be more like 1HP.

 

[droopsnoot]

plus I'm going to be working quite a way from the nearest plug scocket and it sounds like the higher power motors with the 100litre units won't like being fed through extension leads.

I've got a 50l 3hp Sealey compressor, and have had some issues (discussed on here somewhere) with it blowing the fuse on the extension lead RCD unit in the colder weather. I fixed it by moving the compressor to the wall socket and buying a longer pipe, which also had the side-effect of making it much quieter. It does spend a lot of time filling the air tank if I'm using stuff like the cut-off tool or die grinder, but there's stuff I can do with those that I can't (cheaply) replicate with electric tools.

 

[droopsnoot]

So here's two pics of the spec plate off the air compressor. It does look like 3HP as they said and the power is 6.5x220=1.43kW
Any ideas ?

View attachment 62675

I know it makes me sound like an internet anorak, but you do have to wonder how accurate anything is when they can't spell "Executive" or "Dimensions" properly.

 

[skotl]

I'm still not convinced, it says the current is 6.5A which means the power cannot be more than 1560 watts, ~2HP but it will be less than because of energy lost to inefficiencies. According to this page, a 6.5 amp motor is going to be more like 1HP.

I concur. Unless they've bent the laws of physics, that's nae a 3hp compressor.

And if it was, I'd be wondering what stable the lazy third horse was lying down in, if it was only generating 7.5cfm

 

[normspanners]

And if it was, I'd be wondering what stable the lazy third horse was lying down in, if it was only generating 7.5cfm

they do use 3 horses-------accept two of them have been hobbled.