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Measuring the effectiveness of a sandblaster?



 
 
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  #1  
Old June 12th 09, 08:56 PM posted to rec.aviation.homebuilt
Michael Horowitz
external usenet poster
 
Posts: 159
Default Measuring the effectiveness of a sandblaster?

I know the compressor requirements are stated when considering a
sandblaster, but is there anyway to measure the effectiveness e.g. is
my blaster taking off paint as quickly as someone elses?

As an example, I can take off an 1/8" strip of paint at about
1"/second, but have no idea what should be happening - Mike

  #2  
Old June 12th 09, 09:45 PM posted to rec.aviation.homebuilt
Anyolmouse
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Posts: 138
Default Measuring the effectiveness of a sandblaster?


"Michael Horowitz" wrote in message
...
| I know the compressor requirements are stated when considering a
| sandblaster, but is there anyway to measure the effectiveness e.g. is
| my blaster taking off paint as quickly as someone elses?
|
| As an example, I can take off an 1/8" strip of paint at about
| 1"/second, but have no idea what should be happening - Mike
|

To take a lot off in one pass you have to have a industrial capacity
compressor and nozzle. 100 to 115psi @ 5 to 7cfm doesn't give you much
except for cleaning small parts. A water separator is a must. A
commercial shop I use shuts down when the humidity is high. They use an
old Military surplus compressor that puts out close to 100cfm @ 150psi
or there-a-bouts. FWIW yours is doing about what my old Sears
compressor/blaster used to do.

--
But a Constitution of Government once changed from Freedom, can never be
restored. Liberty, once lost, is lost forever.
John Adams, letter to Abigail Adams, July 17, 1775

Anyolmouse

  #3  
Old June 12th 09, 11:48 PM posted to rec.aviation.homebuilt
Bob
external usenet poster
 
Posts: 42
Default Measuring the effectiveness of a sandblaster?

On Jun 12, 12:56*pm, Michael Horowitz wrote:

As an example, I can take off an 1/8" strip of paint at about
1"/second, but have no idea what should be happening - Mike

-------------------------------------------------------------------------------------------------

Basic test was to paint a 10" x 2" coupon then cure the paint to spec.

Once th paint was cured you masked-off the surface in strips 2"
wide,giving you four square inches of 'sample surface'.

The coupon was then rigged to a rack at a hight & angle convenient for
the blaster, who got thirty seconds before the flag came down,
indicating the next 2" wide 'surface' was being exposed. Flag goes
up, blaster goes back to work, which is trying to remove ALL of the
paint from ALL of the surface.

The blaster is all suited up, inside a helmet or mask. He's as much a
part of the procedure as the rack or the flag or whatever.

What are they testing? Usually they're comparing one paint against
another, or one abrasive against another, or one nozzle against
another. If they were comparing hobby-type sand-blasting rigs, they
probably run the FULL procedure then take a break, roll in a new rack
of samples AND a new compressor, sand bucket, hose, nozzle & so
forth... and do it all over again.

Guy restoring/repairing an airplane? He'd probably RENT the biggest
rig he could afford, hire someone to keep the hopper filled, use lotsa
pressure, a 'sharp' abbrasive, no grit recovery, etc. -- get the job
done as fast as possible EVEN IF IT DAMAGES SOME JOINTS.

Otherwise, there's lotsa good books on abrasive surface treatment,
most with excellent photographs showing what happens when you go after
small diameter mild-steel tubing when you're armed with a 25hp air
compressor.

-R.S.Hoover
  #4  
Old June 13th 09, 12:30 AM posted to rec.aviation.homebuilt
Morgans[_2_]
external usenet poster
 
Posts: 3,924
Default Measuring the effectiveness of a sandblaster?


"Anyolmouse" wrote

To take a lot off in one pass you have to have a industrial capacity
compressor and nozzle. 100 to 115psi @ 5 to 7cfm doesn't give you much
except for cleaning small parts. A water separator is a must. A
commercial shop I use shuts down when the humidity is high. They use an
old Military surplus compressor that puts out close to 100cfm @ 150psi
or there-a-bouts. FWIW yours is doing about what my old Sears
compressor/blaster used to do.


WoW! I can't even comprehend a compressor that big!

What is the power source; IC engine, or electric, and do you know how big the
power source is, in either HP or amps? That would help me try to put it into
size.
--
Jim in NC

  #5  
Old June 13th 09, 01:42 AM posted to rec.aviation.homebuilt
Anyolmouse
external usenet poster
 
Posts: 138
Default Measuring the effectiveness of a sandblaster?


"Morgans" wrote in message
...
|
| "Anyolmouse" wrote
|
| To take a lot off in one pass you have to have a industrial capacity
| compressor and nozzle. 100 to 115psi @ 5 to 7cfm doesn't give you
much
| except for cleaning small parts. A water separator is a must. A
| commercial shop I use shuts down when the humidity is high. They use
an
| old Military surplus compressor that puts out close to 100cfm @
150psi
| or there-a-bouts. FWIW yours is doing about what my old Sears
| compressor/blaster used to do.
|
| WoW! I can't even comprehend a compressor that big!
|
| What is the power source; IC engine, or electric, and do you know how
big the
| power source is, in either HP or amps? That would help me try to put
it into
| size.
| --
| Jim in NC
|

The compressor is diesel powered and is about the size of my Safari van,
maybe a little bigger. The sand hopper is roughly a 10 ft square funnel
at the top that tapers down to an outlet at the bottom.

The guy that operates it has a helmet with a face plate that has a
leather/canvas breastplate and apron. The delivery hose is about the
size of a fire hose. Filtered air is fed to his helmet to make sure he
has good air to breathe.

They sand blasted a friends old VW beetle in about a half hour. I think
almost half of that was prep time.

--
"We have no government armed with power capable of contending with human
passions unbridled by morality and religion. Avarice, ambition, revenge,
or gallantry, would break the strongest cords of our Constitution as a
whale goes through a net. Our Constitution was made only for a moral and
religious people. It is wholly inadequate to the government of any
other." --John Adams, October 11, 1798

Anyolmouse

  #6  
Old June 13th 09, 04:58 AM posted to rec.aviation.homebuilt
Bob
external usenet poster
 
Posts: 42
Default Measuring the effectiveness of a sandblaster?

On Jun 12, 4:30*pm, "Morgans" wrote:

*WoW! *I can't even comprehend a compressor that big!

What is the power source; IC engine, or electric, and do you know how big the
power source is, in either HP or amps? *That would help me try to put it into
size.
------------------------------------------------------------------------------


Dear Jim,

A modified VW engine makes a pretty good media blaster in the medium-
size range. This is a 96cid engine that is modified so that two
barrels are constantly pumping whilst the other two serve as the power
source (ie, about 15hp). Using a VW bug body as an example, it will
usually take from six to eight hours to strip one of paint, tar, etc.

Tthe really big units are found at dry docks, for treatment of
concrete piers and other heavily encrusted objects.

-R.S.Hoover
-(USN Retired)

  #7  
Old June 13th 09, 05:21 AM posted to rec.aviation.homebuilt
Dan[_12_]
external usenet poster
 
Posts: 451
Default Measuring the effectiveness of a sandblaster?

Bob wrote:
On Jun 12, 4:30 pm, "Morgans" wrote:

WoW! I can't even comprehend a compressor that big!

What is the power source; IC engine, or electric, and do you know how big the
power source is, in either HP or amps? That would help me try to put it into
size.
------------------------------------------------------------------------------


Dear Jim,

A modified VW engine makes a pretty good media blaster in the medium-
size range. This is a 96cid engine that is modified so that two
barrels are constantly pumping whilst the other two serve as the power
source (ie, about 15hp). Using a VW bug body as an example, it will
usually take from six to eight hours to strip one of paint, tar, etc.

Tthe really big units are found at dry docks, for treatment of
concrete piers and other heavily encrusted objects.

-R.S.Hoover
-(USN Retired)


The VW engine idea sounds interesting. Any suggestions where to find
plans? I don't think Id build one, but it should be an interesting read.

I would imagine such Navy machines would be a tad noisy. I have
never had the pleasure of hearing a rivet gun used in building large sea
going vessels. I have the feeling it also would be a bit loud.

Dan, U.S. Air Force, retired
  #8  
Old June 13th 09, 06:01 AM posted to rec.aviation.homebuilt
Tim[_8_]
external usenet poster
 
Posts: 27
Default Measuring the effectiveness of a sandblaster?


"Dan" wrote in message
...
Bob wrote:

A modified VW engine makes a pretty good media blaster in the medium-
size range. This is a 96cid engine that is modified so that two
barrels are constantly pumping whilst the other two serve as the power
source (ie, about 15hp). Using a VW bug body as an example, it will
usually take from six to eight hours to strip one of paint, tar, etc.

Tthe really big units are found at dry docks, for treatment of
concrete piers and other heavily encrusted objects.

-R.S.Hoover
-(USN Retired)


The VW engine idea sounds interesting. Any suggestions where to find
plans? I don't think Id build one, but it should be an interesting read.

I would imagine such Navy machines would be a tad noisy. I have never
had the pleasure of hearing a rivet gun used in building large sea going
vessels. I have the feeling it also would be a bit loud.

Dan, U.S. Air Force, retired


You can do the same with the old 289/302 Ford engines. I rented a jack
hammer from a local rental supply company many years ago, that was a
tankless compressor built on a trailer with nothing more than a 302 Ford
with one stock head, and one compressor head.



  #9  
Old June 13th 09, 06:37 AM posted to rec.aviation.homebuilt
[email protected][_2_]
external usenet poster
 
Posts: 33
Default Measuring the effectiveness of a sandblaster?

On Jun 12, 10:21*pm, Dan wrote:

* * The VW engine idea sounds interesting. Any suggestions where to find
plans? I don't think Id build one, but it should be an interesting read.
Dan, U.S. Air Force, retired


http://dunnrightinc.com/

Great use for those VW parts that really shouldn't be put back on the
road much less in the air..........................
====================
Leon McAtee

  #10  
Old June 13th 09, 01:13 PM posted to rec.aviation.homebuilt
routund
external usenet poster
 
Posts: 5
Default Measuring the effectiveness of a sandblaster?

Dan wrote:

Bob wrote:
On Jun 12, 4:30 pm, "Morgans" wrote:

WoW! I can't even comprehend a compressor that big!

What is the power source; IC engine, or electric, and do you know how big the
power source is, in either HP or amps? That would help me try to put it into
size.
------------------------------------------------------------------------------


Dear Jim,

A modified VW engine makes a pretty good media blaster in the medium-
size range. This is a 96cid engine that is modified so that two
barrels are constantly pumping whilst the other two serve as the power
source (ie, about 15hp). Using a VW bug body as an example, it will
usually take from six to eight hours to strip one of paint, tar, etc.

Tthe really big units are found at dry docks, for treatment of
concrete piers and other heavily encrusted objects.

-R.S.Hoover
-(USN Retired)


The VW engine idea sounds interesting. Any suggestions where to find
plans? I don't think Id build one, but it should be an interesting read.

I would imagine such Navy machines would be a tad noisy. I have
never had the pleasure of hearing a rivet gun used in building large sea
going vessels. I have the feeling it also would be a bit loud.

Dan, U.S. Air Force, retired


Here is an exchange from several years ago hear on RAH.

========
"Bruce A. Frank" wrote:

I helped build a Chevy 327 into a compressor many years ago. We kept it
simple and crude. Every other cylinder in the firing sequence was made
into a pumping cylinder. The intake manifold runners to each compressor
cylinder was plugged with a chunk of wood and JB Weld epoxy to prevent
fuel mixture from flowing there. A hole was drilled in each compressor
cylinder runner between the epoxied plug and the intake valve. those
four holes were piped together to draw air from an air cleaner element.
The rocker arms on each of the compressor cylinders were removed and a
hardware store light spring installed in place of the normal intake
valve spring. This allowed the intake valve to open every time the
piston headed down, rather than just on the "intake cycle" of the
cylinder. A check valve replaced the spark plugs so every up stroke of
the piston compressed air. The Chevy 327 ran like a top and produced
enough air at 4000 rpm to power a small jack hammer. It seems we
calculated 200+ cfm at 100 psi. Intake and exhaust were muffled so it
ran very quietly.

--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
BAFRANK(at)worldnet.att.net Homebuilt Aircraft Newsletter"
| Publishing interesting material|
| on all aspects of alternative |
| engines and homebuilt aircraft.|
*------------------------------**----*
\(-o-)/ AIRCRAFT PROJECTS CO.
\___/ Manufacturing parts & pieces
/ \ for homebuilt aircraft,
0 0 TIG welding

While trying to find the time to finish mine.

========

Tony P wrote:

HI Bruce.

So YOU'RE the guy who built that one I saw! That explains it. I even
think it was an SBC engine.

Sounds pretty similar to what I saw, but somehow I think the thing
plugged along at idle most of the time and just accelerated as needed.
Maybe it vented off surplus?

Also had a neat loping sound. The powered cylinders clearly had no
difficulty keeping up, probably ridiculously overpowered.

Tony Pucillo

--


I speak only for myself unless otherwise stated.
One personality is enough, thank you.

"Irony better befits a gentleman than buffoonery;
the ironical man jokes to amuse himself,
the buffoon to amuse other people." (Aristotle, 'Rhetoric')

========

"Bruce A. Frank" wrote:

From empty tank to full, from start up to pop off, was about 20
seconds (50 gal tank). While we were using it it ran at about 1000 rpm.
With the jack hammer we turned it up to 4000 rpm and with the JH running
full bore the pop off valve was always blowing. When we put the
commercially mfg. controller on it the rpm hardly ever got above 500 (the
tank would fully pressureize before the engine reached its controller
set 2500 rpm). Last I heard it was still running just fine (30 years
now! and the engine had 90,000 miles when we converted it with no
overhaul) Ours had a sort of pocketta-pocketta sound, much like an
antique 4 cylinder engine.

An interesting side note, the air out of that engine was as oil free and
clean as if it had been charcoal filtered. There was no exhaust gas
blow-by smell or gasoline smell. A friend in PA built the same thing for
a sandblast outfit. It'll pump through 600 lbs of sand at 130 psi in
about 15 minutes.

--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
BAFRANK(at)worldnet.att.net Homebuilt Aircraft Newsletter"
| Publishing interesting material|
| on all aspects of alternative |
| engines and homebuilt aircraft.|
*------------------------------**----*
\(-o-)/ AIRCRAFT PROJECTS CO.
\___/ Manufacturing parts & pieces
/ \ for homebuilt aircraft,
0 0 TIG welding

While trying to find the time to finish mine.


 




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