shop-talk
[Top] [All Lists]

Re: Air Compressors - more

To: shop-talk@autox.team.net
Subject: Re: Air Compressors - more
From: "John T. Blair" <jblair@exis.net>
Date: Sun, 11 Feb 2001 10:43:30 -0500
>Hey Gang,
>
>as a fellow owner of one of the infamous Sears 6.5 upright oil/airless 60
gal 
>models, I've got a couple semi-sacrilegious thoughts.  First, has anyone 
>checked out Sears' new twin cylinder model?  I know, I know... but they're 
>just so darned close-by and convenient and all....

A couple of more thoughts:

My dad has had a 4HP 20gal (110V) Sears (oil lub) compressor for almost 30
years and it is still going.  We use it for painting cars, sandblasting and
various air tool.  I'll admit that once we start using a tool, the compressor
will run almost continuously, but it gets the job done.

When I went looking for a compressor, I had Sears had both the oil less and
the oil lubed types.  I purchased a 5hp 30gal (220V) one and have been using
it for over 10 years.  Again, I have a sandblast cabinet, a pressure blaster,
spray guns, etc.  I've used this compressor for restoring 2 cars and can't
say anything bad about it.

When I bought mine, I noticed the oil less was about $100 cheaper for the 
"same" basic specs. ie. 5hp 30gal tank.  When I asked the sales person what
the difference was, no one could really tell me why it was cheaper or which
one was better and or why.

Personal obervations:

1 - I've been on this list and other that periodically talk about
compressors.  
    The main group I hear complaining about theirs are the owners of the oil 
    less one.

2 - What is the duty cycle of a compressor supposed to be?  When I start using
    a tool, the compressor will lag, start running, a short time after I start
    the tool.  But when I release the tool, the compressor will shot off
    shortly after I release the tool.

    Is this a bad thing?  When we use a portable gas generator, it's motor
    run continiously.  When we drive our cars, the motor runs even when we
    are stopped.  So why can't or shouldn't the compressor run when we are
    using the tool?

3 - Many years ago, I was working on submarine simulators for the Navy.  One
    of the projects I had, was to develop an emergency air breathing system
    for one of the simulators.  At that time, I found out about "oil less"
    compressors.  I had to use and oil less compressor for breathing air.
    Since I don't have a pressurized hood and breath air from my compressor,
    I don't see the need for the hobby oil less - except that they are 
    cheaper than the oil lubed.

4 - The only 2 things I can find out about the oil less compressors are:
    a. they are usually cheaper than the oil lubed ones.
    b. they are cheaper to repair.

    I will also assume that you have to repair (replace the diaphrams) 
    periodically.  At least more often than you have to rebuild an oil
    lubed compressor.

Finally, yes, I would probably like a two stage compressor that would 
supply about 130psi.  But do I really need it?  Maybe this is where 
our thinking is flawed.  To me, if my tool doesn't drastically slow
down when I'm using it, I don't see anything wrong with the compressor
running while I'm using the tool.

The only time I've really had to wait on my compressor was when using a
DA sander to sand my van.  But I must admit that usually by the time the
sander starts to slow down (say 5 min) I want a short break or I have to
reposition myself.  The compressor catches up.

One finaly comment, my compressor is mounted under my workbench at the 
back of the garage.  I have hung a large box fan behind it to help move
the air under the bench to help cool it on very hot hummid summer days.

John


    

John T. Blair  WA4OHZ          email:  jblair@exis.net
Va. Beach, Va                  Phone:  (757) 495-8229

48 TR1800    48 #4 Midget  65 Morgan 4/4 Series V
     75 Bricklin SV1   77 Spitfire     71 Saab Sonett III

Morgan:    www.team.net/www/morgan
Bricklin:  www.bricklin.org

///
///  shop-talk@autox.team.net mailing list
///


<Prev in Thread] Current Thread [Next in Thread>
  • Re: Air Compressors - more, John T. Blair <=