On Wed, 4 Oct 1995, Chris Chubb wrote:

> I know we talked about air compressors here a bit back. I listened,
> and am ready to go get my first air compressor. I think that
> I will need it to get some of the work on the fastback done,
> and it would make some of my work on the Bus easier as well.
> 
> I want to buy my first compressor. It needs to be portable,
> and it needs to be cheaper than $500. 
> 
> I want to do painting, impact wrench, sander, some light sandblasting
> with it. Mabye some house painting, etc.
> 
> I have been looking and it looks like a 5 HP compressor with a 
> 20 gallon tank should cover it.
> 
> I have looked carefully at the Craftsman and the Campbel-Hausfield (sp?)
> compressors. The Craftsman compressor hos a slightly higher airflow
> rating, (11 SCFM@90) is oilless, and direct drive. 
> The C-H compressor has a slightly lower rating (9.5 SCFM@90PSI)
> but boasts a cast iron pump and belt drive.

There is a lot of over estimating the performance of ac's in the "home" 
capability range. This has been discussed in other forums. The sum seems 
to indicate that Sears is one of the prime offenders in this matter.

> Some 
questions that nobody (At the store) seems to be able to > answer:
> 
> Cast Iron:If the pump is not cast iron, what is it, aluminum? Is cast iron
> going to last much longer than the alternative? What does it get
> me for the higher price.
> 
> Direct Drive: Other than compactness, what is the difference between
> directr drive and belt drive, other than the belt? Are the belts
> quieter or more noisy?
> 
> Oilless: My engineering training makes me cast the hairy eyeball on 
> something that says 'lubed for life.' Without the oil, I should not
> need a seperator if I want to paint, etc. But, a seperator is not
> that expensive. Does the oil let the pump last longer, run cooler,
> what? Or, does it just make up for the shortcomings of cast iron?
> 
Is the "Oilless" really a piston type compressor? At least in the past 
oilless reffered to a diaphram pump and was only sold at the lower 
capability ranges. If this is still true I would not touch the ac with a 
10 foot pole. 

I would note that all the commercial type ac's seem to use piston pumps 
with cast iron cylinders being the norm. The virtue of cast iron 
cylinders is the excellant wearing/life of cast iron. Some what the same 
reason is why most cars use ci engine blocks. 

> The C-H compressor seems much heavier. I think the tank walls are 
> stronger, and the pump is definately heavier. It is also about
> 15% more expensive, and about 10% less powerful (by the specs).

The weight difference is consistent with the Sears use of a diaphram pump 
instead of the more traditional ci block and aluminum piston arrangement 
of CH. Really check out this point on whether Sears is using a D pump.

At least in my area the CH ac's are discounted to about $400 (Home Depot, 
Auto Parts Club, etc. I should point out that my 5 hp CH ac uses 220v 1 
phase power. This is not a problem with me but is it ok for your use? 
Does the Sears unit require 220v?

> Is there another widely availible compressor that I
should be 
> looking for? I only want to spend the money once, for a loooong
> time, but I am limited to about $500 including a seperator, drier,
> etc. that I need to make it functional.
> 
I bought the CH you are talking about and have used it extensively for 
about 3 years in restoring an old Ford pu. My main useage has been in 
sand blasting, cabinet bead blasting and tools such as grinders, drills, 
cut offs, etc. I am quite satisfied with the CH even though in the real 
world I have had a few problems that I handled myself w/o the aid of the 
service types. 

In my experience you must stay inside the duty cycle limits of the ac you 
buy. The sales men? seldom if ever discuss this point. Look at the manual 
before buying to find these limitations. 

The key to any happy use of an ac is to set up a rig to condense the 
water naturally produced and to prevent it from entering the tools you 
plans to use. This is critically true of sand blasting and painting. This 
is NOT just buying a water filter. The question of oil in the airflow is 
IMHO nowhere as important. If you solve the water to have takem a big 
stride in solving the oil problem.

To avoid prolonging this reply e-mail me if I can be of any assistance. 

> 
> -- 
> -- Chris Chubb (cchubb@ida.org) - (703)-845-2287 [Alexandria, VA, USA]
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