Subject: Re: air compressor: quiet air supply

From: Mike Rehmus <[email-masked]>
Date: 23 Mar 1995 01:34:06 GMT

[email-masked] (R.C. Jones) wrote:
>
> 
> I have a Sears 3 hp air compressor that is about five years old.
> When I use it for extended buffing/polishing now, it generates
> an "expensive"  knocking sound that makes me think I'll need to
> get a new one soon.

The Sears compressors are not that hard to repair.  You can also
purchase new compressors to mount on your old tank.

Normally, they only make this kind of sound if you don't frequently,
every 100 hours or so, change the oil or the air filter.

Sometimes the reed valves need to be replaced because they break,
bend, and/or corrode.

best,

Mike

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From: Mike Rehmus <[email-masked]>
Date: 23 Mar 1995 01:34:13 GMT

best,

Mike

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From: [email-masked] (Jon Lake)
Date: 23 Mar 1995 01:58:16 GMT

I would like to make some small flat prototype parts and I think that
chemical etching would give me the best quality.  Are there any
"hobbiest" kits out there for chemical etching or should I try to
avoid doing this myself?  I would like the material to be copper, but
aluminum would work.  On occasion, I would like to make small, flat
springs out of spring steel shim stock, can I make them with chemical
etching?  Some of this stuff would be a little difficult to machine on
a mill.
Alternatively, if the experts recommend against a small shop attempting
this, is there anyone out there that does low, low volume chem etching
in the San Francisco Bay area?
TIA,    jon

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From: [email-masked] (jim janecek)
Date: Wed, 22 Mar 1995 13:43:55 -0600

In article <[email-masked]>,
[email-masked] (R.C. Jones) wrote:

>  Is there an FAQ on compressors? Could anyone recommend a preferred model?
> I've heard that the "beltless/oil-less" ones are not so good. Comments
> would be sincerely appreciated.

I probably have the same model you do, only mine is about 6-7 years old.

I've had no problems with it, have you ever changed the oil?
If you can't figure out what's causing the knocking, you could just wait
for it to fail, take it apart, (they're not that complex) and relace the
parts from SEARS....

If you still have the manual, if you don't I could copy the parts section
and send it to you.
You might spend $150 in parts, but that's cheaper than a whole new compressor.

I also mistakenly purchased one of the newer 3hp "oil-less" direct-drive
compressors and although its lighter (I move mine around a lot) it is the
NOISIEST thing I have ever heard.

If you wish to purchase another new belt-drive piston compressor, I'd go
with a 2-3hp version from Grainger.  They are very quiet and seem to be
much more reliable than the Devilbliss brand that Sears sells.

-- 
Jim Janecek
[email-masked]
Personal Effects inc.

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From: [email-masked] (Ron Ginger)
Date: Wed, 22 Mar 1995 21:47:33 LOCAL

In article <[email-masked]> [email-masked] (Jon Lake) writes:
>From: [email-masked] (Jon Lake)
>Subject: chemical etching question
>Date: 23 Mar 1995 01:58:16 GMT

>in the San Francisco Bay area?

This is often done by scale modelers. Look at rec.models.scale. There have 
been a few discussions recently about this, including a pointer to a few 
places that will do custom work, one off.

I just tried to make an etched brass name plate for a model I just finished. I 
bought some transfer paper sold for making printed circuit boards, printed the 
design on my laser printer, then ironed it onto the brass. My results were 
poor. I got a lot of bluring of lines.  I intend to get back to this someday. 

Has anyone else used this transfer film?

The etching is easy- you can buy a bottle of the echant at Radio Shack stores, 
cheap- about $5. 

Ron Ginger
my signature is http://www.ultranet.com/~ginger

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From: [email-masked] (Tim Jensen)
Date: Thu, 23 Mar 95 04:20:16 GMT

In article <[email-masked]>, [email-masked] (R.C. Jones) writes:
>   |___________________________________________________________________| 
> >>| Dik Jones, Earth Model Interpretation   Internet: [email-masked] |
>   | Chevron Petroleum Technology Company.        Tel:  (310) 694-7056 | 
>   | La Habra, California 90633-0446              Fax:  (310) 694-7063 |  

  Hmmm.. I have a Sears 5 hp model that has made an expensive sounding
knock right from the start :-) It seems to work ok for the price though.
  I would certainly stay away from the oilless direct drive compressors.
For quiet operation any of the good compressors with a cast iron pump
are ok. Expect to pay $1000.00 + for a good 3 hp. That's why I have a Sears
with an aluminum pump. Another idea might be to buy a good pump to put on 
your existing Sears tank. That's what I intend to if the pump on my Sears
ever quits. Devillbess(sp??) makes excellent pumps as does Gardner-Denver.
Sanborn pumps are good too, or at least they used to be. Check with 
W. W. Grainger. They sell compressors and pumps along with tons of other
stuff. Hope this helps

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From: [email-masked] (R.C. Jones)
Date: 22 Mar 95 16:43:28 GMT

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From: [email-masked] (Daryl Bender)
Date: Thu, 23 Mar 1995 18:04:53 -0500

In article <[email-masked]>, [email-masked] (Jon

> in the San Francisco Bay area?

It's not that hard to do. Its usually called photochemical etching. It
works very well on copper and copper based alloys. You will need a UV light
source and you should see some discussion of that still lingering in this
group. You will need some resist, developer and etchant (ferric cloride)
usually found at an electronic parts store in the "do it yourself PCB"
section. The basic process is clean the metal, pour on resist (under red
light conditions) let dry (short 200oF bake in oven helps) (resist becomes
more light sensitive when dry) place your phototool on top of the metal &
held down with a piece of glass, expose under UV light source, remove glass
and phototool and develop coated metal (red light conditions end), rinse,
200oF bake in oven to harden coating, etch. If you can spray the etchant
hot it etches faster and undercutting (eating in then under causes fatter
lines) is minimized.
You can make phototools with a laserprinter that has been fed
transparencies. Also I have also sometimes sprayed the entire part with
black (or whatever) laquer. The paint bonds excellently to the etched lines
and elsewhere it is sitting on a resist coating. Take a wood block with
medium emery and sand away. The pattern literally emerges under the sanding
block. Just watch any wide etched areas (ie not lines) and sand carefully
around the edges. Then you sand finer and finer ending up with 0000 steel
wool. 
I'm not sure how well this process works on steel (likely different
chemicals for sure) but you could make your springs from berilium copper.
I feel you should also be ecologically responsible with the chemicals as
they are noxious (developer especially). Take them for proper disposal when
done. Don't dump them down the drain.

Daryl
-- 
Working, but not speaking for BNR.

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From: [email-masked] (Bob Powell)
Date: 24 Mar 1995 07:03:54 GMT

I've had a "PUMA" for 2 years, compressor made in Taiwan but has
a high-efficiency US-made induction motor.  Labeled 3 HP, draws
18A @ 120V, rated 4cfm @ 90psi.  Conventional belt-drive, oil in
the crankcase, works mounted over a 30 g horizontal tank, and
weighs a ton.  Very quiet, not at all unpleasant to have inside
the shop.  Cost $300 at a local contractor's tool store.  Seems
to be just right for my needs (nail guns, impact wrench, but no
"continuous drive" tools like die grinders).

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From: [email-masked] (Jonathan M. Elson)
Date: 23 Mar 1995 06:40:53 GMT

Jon Lake ([email-masked]) wrote:
: I would like to make some small flat prototype parts and I think that
: chemical etching would give me the best quality.  Are there any
: "hobbiest" kits out there for chemical etching or should I try to
: avoid doing this myself?  I would like the material to be copper, but
: aluminum would work.  On occasion, I would like to make small, flat

This is very similar to the manufacture of printed circuit boards.  The metal
on a PC board is about .001 to .002 copper, laminated to a fiberglass
substrate.  What you want to do is exactly the same thing without the
substrate.  I have tried several processes, and had poor results.
The material I now use is "dry film resist", made by DuPont and others.
It is a standard material in the printed circuit industry.  It is hot-roll
laminated onto the copper, exposed to UV light through a photo-master,
and developed with Sodium Carbonate.  The copper is then etched with Ferric
Chloride, or similar acidic etchant.  (Alkaline etchants will dissolve
the resist.)  The resist is then stripped with Lye (I use Drano crystals,
making a new solution each time).  This process is discussed in newsgroup
alt.electronics.cad in much detail.  This process should work fine for you,
too.  Making the photo-master from a laser printer output is a little tricky.
I contact expose KODAK GLP-7 photoplotter film, and then may contact print
that again to get back to a positive.  Any high-contrast litho film will 
work.  It takes a lot of light to penetrate the laser printer paper, so
you might want to use laser transparencies.  You probably still need the
litho film, however, because the contrast ratio of laser printer output is
not as high as you might think.  Copying to the litho film greatly enhances
the contrast of the laser printed original.  If you have any questions,
E-Mail me.  Oh, yes, the dry film resist is available from suppliers to the
printed circuit board industry.  Kepro in St. Louis sells it, among others.