Re: Air Compressors

[jlandry@domain.elided (John A. Landry)]

When the truth serum kicked in, Chad Sibert <csibert@domain.elided> blurted
out...

>This is kind of Scout related.  I'm looking to buy a compressor to aid
>in the 800 restoration.  What do you guys think of the newer oil free
>compressors sold by Lowes, Home Depot, Sears, etc.?  Are they reliable,
>or should I spring for the more traditional twin-cylinder and separate
>motor design?
>
>The rated output seems to be the same, but the older design runs about
>$100 more.  What's the difference in the two?

Chad,

Like Dan I have one of the Sears oil free models.  Without looking, I think
mine's a 4 HP with a 13 gallon tank.  I have a sneaky suspicion that DeVilbis
makes the oil free air compressors for Sears.  I saw one with their name on it
and it look identical.

Anyway, the difference is in the way the pump is constructed.  The traditional
models use one or more pistons in a cast iron cylinder with a oil filled
crankcase... much like a small Briggs and Stratton engine.  The newer oil free
types use a cylinder lined with a teflon sleeve.  The piston in the oil free
type is thin like a pancake and basically a metal disk holding a teflon lip
all the way around.  This thin piston is pumped up and down in the sleeve to
compress the air.

The thought is that for heavy continuous use, a well built oil type compressor
pump will outlast the oil free type.  But for home use and light business use,
the oil free are more than adequate.  For one thing, the teflon cylinder
sleeve and piston are easily replaced in the Sears oil free design.

I've been very happy with the performance of my compressor.  The only thing
outwardly different from older compressors is the different sound an oiless
makes.  I can only describe it as a sort of *loud* growling sound.  I use mine
for running all sorts of air tools including a sand blaster.  I'd consider 4
HP to be about the minimum you want to get... bigger is better for both the
pump HP and tank size.

Take care,

John L.
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