Air compressors

[Gregor 4,847]

Going to let my stupid out again. How do they rate the HP on an air compressor? I know my compressor  does not have a 3 1/2HP motor on it, but the compressor is rated at 3 1/2" HP. My 14 HP tractors have 14 HP motors on them.  What am I missing? So when a media blaster says it requires a 1 HP compressor, what are they really saying?

[Achto 27,818]

The HP rating is for the motor on the compressor. Electric motor HP rating have always confused me a bit. Example : the 220v 5hp motor on a Rol-Air compressor is about twice the size and weight of the 220v 5hp motor on my Sandborn compressor. Both motor are supposed to have the same HP, granted the duty cycle on the Sandborn is lower.  

 

When sizing a compressor to a tool, pay no attention to the HP rating of the compressor. CFM (cubic feet per minute) is what really matters. If the CFM on your compressor is not at or above the CFM required for the tool then it will not keep up under constant use of the tool.

[bc.gold 3,403]

Air pressure and CFM determines horse power required to reach those limits.

 

A decent compressor motor would usually have start and run capacitors.

 

[Gregor 4,847]

Not sure I can justify a $1500 compressor. I guess if I can justify 11  tractors on less than 1/2 acre...........

[bc.gold 3,403]

1 minute ago, Gregor said:

Not sure I can justify a $1500 compressor. I guess if I can justify 11  tractors on less than 1/2 acre...........

 

Paint the new compressor Wheel Horse red and the wife wont take notice.

[Gregor 4,847]

On the other hand, in the last couple of years, between Lawn Boys and tractors, I have probably more than that on media blasting. $80 for 1 Lawn Boy mower deck. I have rebuilt over 20, getting most of them blasted. Who knows, maybe I could pick up some blasting work when weather permits. 

[Achto 27,818]

3 minutes ago, Gregor said:

Not sure I can justify a $1500 compressor.

 

I have been using one of these for about 20yrs. This one says Master Force but I'm quite sure that it is made by Sandborn. Probably not the right compressor if you were running a business but it is a good compressor for most home shops. 

First thing that I did to mine was to reset the pressure switch so that it shuts down at 125psi and kicks back in at 100psi, I thought that 155psi was a little over board for a single stage compressor. Some tools that I have will over run the compressor, 4"grinder, mud hog, & sandblaster but I never have to wait very long for it to catch up.

 

https://www.menards.com/main/tools/air-compressors/masterforce-reg-belt-drive-60-gallon-155-psi-stationary-electric-vertical-air-compressor/mela3706056/p-1444439609007-c-12910.htm?tid=-4007114158737362003&ipos=1  

[pacer 3,174]

Cubic Feet Minute/ CFM

 

This cannot be stressed enough, that feature should be THE guide for you in any purchase of an air compressor!!! Horsepower, PSI, tank size, etc are all secondary factors.

 

If you are gonna run air tools or a blast cabinet, then to be able to run these properly you need one with, at a minimum, 10-12cfm - even better is over 15cfm. (to get this I would believe you would need a 2 stage pump)  A blast cabinet in particular is an 'air hog'. My 80gal, 5hp is rated at 19cfm and when using it on a large item it will often run constantly.  Even the little - very handy die grinders - will gulp a lot of air. Paint gun, nail gun, blow gun, air tires, etc, most any of them will do.

 

Having said that, fooling with/rebuilding these horses, (like so many of us do) a blast cabinet has to be one of the most useful tools I have. At the age of most - all? of them have been left outside, not maintained properly, etc etc, getting those rusted, gunked up parts cleaned is made SO much easier with a good compressor and cabinet.

[Gregor 4,847]

1 hour ago, pacer said:

If you are gonna run air tools

I can't stand the noise of air tools. I am perfectly happy with my battery operated tools, but I sure would like to have a blaster, of some kind.

[lynnmor 7,354]

When comparing CFM, be sure that you take into account the PSI where it is rated, example:

• 13.4 CFM at 40 PSI
• 11.5 CFM at 90 PSI

[Achto 27,818]

2 hours ago, Gregor said:

I can't stand the noise of air tools. I am perfectly happy with my battery operated tools, but I sure would like to have a blaster, of some kind.

 

 There is always the E-tank route

 

 

[bc.gold 3,403]

7 hours ago, pacer said:

Cubic Feet Minute/ CFM

 

This cannot be stressed enough, that feature should be THE guide for you in any purchase of an air compressor!!! Horsepower, PSI, tank size, etc are all secondary factors.

 

If you are gonna run air tools or a blast cabinet, then to be able to run these properly you need one with, at a minimum, 10-12cfm - even better is over 15cfm. (to get this I would believe you would need a 2 stage pump)  A blast cabinet in particular is an 'air hog'. My 80gal, 5hp is rated at 19cfm and when using it on a large item it will often run constantly.  Even the little - very handy die grinders - will gulp a lot of air. Paint gun, nail gun, blow gun, air tires, etc, most any of them will do.

 

Having said that, fooling with/rebuilding these horses, (like so many of us do) a blast cabinet has to be one of the most useful tools I have. At the age of most - all? of them have been left outside, not maintained properly, etc etc, getting those rusted, gunked up parts cleaned is made SO much easier with a good compressor and cabinet.

 

I run my two stage on an 80 gallon tank at 175 psi with cut in at 150 psi, regulated at 90 psi output which is what most air tools call for, and my paint gun calls for 70 psi.

 

The large 80 gallon tank is good at cooling the air to remove moisture, then I also have a pair of moisture traps.

Edited December 9, 2021 by bc.gold

[bc.gold 3,403]

2 hours ago, Achto said:

 

 There is always the E-tank route

 

 

 

Your iron oxide has many uses, you can add it to your concrete to give it some color, make thermite or use it as a pottery glaze.

[oliver2-44 9,874]

6 hours ago, bc.gold said:

 

 make thermite 

???

Edited December 10, 2021 by oliver2-44

[bc.gold 3,403]

35 minutes ago, oliver2-44 said:

???

Did I misspell thermite?

 

Make Iron Oxide for Thermite

 

 

 

Edited December 10, 2021 by bc.gold

[rjg854 11,498]

Anyone have experience with California compressors?  I'm not looking for the biggest, fastest, bestest.  I just want to replace the Kobalt one I have with something you can be in the same room with 

[pacer 3,174]

8 hours ago, rjg854 said:

something you can be in the same room with

 

Heh!, aint they LOUD ....

Theyre called 'oilless' and thats because .... well, they dont use oil in the compressor pump!  and to my thinking that is why they are SO loud. The piston is not enclosed in a 'block' to dampen all that motion.

 

Far as I can tell you will have to get up to a 'oiled' compressor and they dont seem to make that till you get on up into the more expensive ones. Course then they too can be a bit noisy because they ARE bigger. If you want to stay in the smaller types without the noise you'll probably have to prowl CL, facebook, garage sales, etc for a used one. Way back when .... 20-30....40? yrs ago the small compressors were oiled types - Sears, Sanborn, and many others had them in horizontal tanks of 20 or so gallons ran on 110 volts and they really were ... quite quiet .

 

[kpinnc 12,572]

On 12/9/2021 at 7:08 AM, Gregor said:

Not sure I can justify a $1500 compressor. I guess if I can justify 11  tractors on less than 1/2 acre...........

 

It took me years to convince my wife that they are NOT "lawnmowers"... 

 

In other words, acreage is not a factor!

[Jrain 276]

On 12/10/2021 at 5:29 PM, pacer said:

 

Heh!, aint they LOUD ....

Theyre called 'oilless' and thats because .... well, they dont use oil in the compressor pump!  and to my thinking that is why they are SO loud. The piston is not enclosed in a 'block' to dampen all that motion.

 

Far as I can tell you will have to get up to a 'oiled' compressor and they dont seem to make that till you get on up into the more expensive ones. Course then they too can be a bit noisy because they ARE bigger. If you want to stay in the smaller types without the noise you'll probably have to prowl CL, facebook, garage sales, etc for a used one. Way back when .... 20-30....40? yrs ago the small compressors were oiled types - Sears, Sanborn, and many others had them in horizontal tanks of 20 or so gallons ran on 110 volts and they really were ... quite quiet .

 

Pacer is spot on with what he said ,but  you have to be patient and keep your eye on CL and FB market place , and I would add think of older air compressors like a older wheel horse ,they are built to last , when I was looking for another air compressor  about 5 years ago that is what I did , I scored a   Kellogg  2 stage 80 gallon for $300 ,  its big .it quiet and runs like a dream ,I have a old speed air 60 gallon single stage in my other garage its ok but no comparison to the Kellogg , its rebuildable and new parts are easy to find .