Measuring the effectiveness of a sandblaster?

[Michael Horowitz]

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

[Anyolmouse]

"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

[Bob]

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

[Morgans[_2_]]

"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

[Anyolmouse]

"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

[Bob]

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)

[Dan[_12_]]

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

[Tim[_8_]]

"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.

[[email protected][_2_]]

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

[routund]

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.

[Stealth Pilot[_2_]]

On Fri, 12 Jun 2009 15:56:48 -0400, Michael Horowitz
> wrote:

>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

mike I never used this because I did all the error and frustration
stuff that went into this.

save up all of your bead blasting work for one big session and go and
hire yourself a trailer mounted diesel engined compressor.
they are not expensive to hire.
one of the brands in australia is Broomwade.

they have the advantage of being able to deliver 120 to 150psi air all
day long.

bead blasting effectiveness is *all* in the pressure.

at 150 psi and using an el cheapo automotive shop style bead blasting
gun you will be cooking!

the same gun at 60 psi will softly polish the surface and remove
nothing.

I used 3 single phase compressors Teed together in the end and the job
still took me 3 weeks.
my mate took my advise and bead blasted his entire fuselage in 1 day
with no time waiting for a pumpup.

by my reckoning an el cheapo bead blasting gun uses about 60cu ft/min
to be effective. if you stick with what you've got, like me you'll be
forever waiting for a pump up.

btw before you start look at the nozzle on your bead blasting gun.
this *will* wear out and the alloy will be shot into the surface of
your aircraft.
it pays handsomly to go and buy a few feet of nylon rod of the same
diameter as the supplied nozzle. cut it all up into the same lengths
and drill out the centre to the same diameter as the supplied one.
the nylon ones will not damage the aircraft and will last marginally
longer. if you've got a supply it is easy to swap in a new one when
they wear out because they are held in place with a set screw.
also if you are using a lathe. machine a little recess in the end so
that they have a small sharp lip. this is incredibly useful for use as
a scraper for dislodging persistent stuff without having to put the
gun down and take the gloves off.
the second most useful tool in bead blasting is a swiss army knife
with a slightly blunt blade. worlds best beadblasting scraper.

......I have the Tee shirt :-)
Stealth Pilot

[Stealth Pilot[_2_]]

On Fri, 12 Jun 2009 15:48:21 -0700 (PDT), Bob >
wrote:

>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

grrrrrrrrrrrr!!!!
use round glass beads called ballottini on aircraft steel. AH grade
from memory works well.
sharp grit will stuff up the fatigue life. round beads will extend it
because they minutely hammer the surface into compression.

use sharp grit and I'll put white ants in yer woodwork.:-)
Stealth Pilot

[Bob]

On Jun 12, 9:21*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.
> ------------------------------------------------------------------------------

There used to be a company named 'Dunn-Rite' (sp?) which supplied a
conversion kit, but the idea dates from the 1930's and the conversion
of anu I-4 or V-8 engine for that purpose. The VW is especially easy
to convert and the DIY method has been explained several times on VW-
specific Groups. Basically, you simply select a pair of sequenctially-
firing cylinders as your power pair (ie, 1-3 or 2-4) and use the other
pair as your 'pumping' cylinders. The spark plugs of the pumping
cylinders are modified to act as ball-type check valves while the
exhaust stack is modified to become an input valve by the use of a
flapper valve made of light-gauge spring steel. The push-rods &
rocker arms of the pumping pair are modified so as to always be
open.

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

> * * I would imagine such Navy machines would be a ta
d 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.

>---------------------------------------------------------------------------------------

Actually, they sound remarkably like welding machines :-)

(I don't think the Navy hasn't used riveted hulls since the 1920's)

-Bob

[Dan[_12_]]

Bob wrote:
> On Jun 12, 9:21 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.
>> ------------------------------------------------------------------------------
>
> There used to be a company named 'Dunn-Rite' (sp?) which supplied a
> conversion kit, but the idea dates from the 1930's and the conversion
> of anu I-4 or V-8 engine for that purpose. The VW is especially easy
> to convert and the DIY method has been explained several times on VW-
> specific Groups. Basically, you simply select a pair of sequenctially-
> firing cylinders as your power pair (ie, 1-3 or 2-4) and use the other
> pair as your 'pumping' cylinders. The spark plugs of the pumping
> cylinders are modified to act as ball-type check valves while the
> exhaust stack is modified to become an input valve by the use of a
> flapper valve made of light-gauge spring steel. The push-rods &
> rocker arms of the pumping pair are modified so as to always be
> open.
>
> ---------------------------------------------------------------------------------
>
>> I would imagine such Navy machines would be a ta
> d 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.
>
>> ---------------------------------------------------------------------------------------
>
> Actually, they sound remarkably like welding machines :-)
>
> (I don't think the Navy hasn't used riveted hulls since the 1920's)
>
> -Bob

I didn't mean to imply the Navy uses riveted hulls. I had just
watched a show on television about Titanic and I was thinking of the
rivets used in that era.

Dan, U.S. Air Force, retired

[Peter Dohm]

"Bob" > wrote in message
...
>On Jun 12, 9:21 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.
>> ------------------------------------------------------------------------------
>
> There used to be a company named 'Dunn-Rite' (sp?) which supplied a
> conversion kit, but the idea dates from the 1930's and the conversion
> of anu I-4 or V-8 engine for that purpose. The VW is especially easy
> to convert and the DIY method has been explained several times on VW-
> specific Groups. Basically, you simply select a pair of sequenctially-
> firing cylinders as your power pair (ie, 1-3 or 2-4) and use the other
> pair as your 'pumping' cylinders. The spark plugs of the pumping
> cylinders are modified to act as ball-type check valves while the
> exhaust stack is modified to become an input valve by the use of a
> flapper valve made of light-gauge spring steel. The push-rods &
> rocker arms of the pumping pair are modified so as to always be
> open.
>
> -Bob
>

They are still around, and have improved dtheir system from the one you
describe.

Here is the link, thanks to Leon in this same thread:
http://dunnrightinc.com/

Peter

[rckchp]

On Jun 12, 3:56*pm, Michael Horowitz > wrote:
> 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

I sandblast for my living (cemetery lettering) and the most common
misconception is more pressure strips/cleans faster.....when actually
the more CFM (cubic feet per minute) is what works best. In the past
when I was an active EAA member I did a few blast jobs on Cub fuselage
structures. I use a 100 CFM compressor, such as used by utility crews
to run jackhammers, etc. Most tool rental places have 85-185 CFM
machines for rent....anything from 50 CFM up will work fine.

There are two "schools of thought" about how much pressure to use when
doing steel tube fuselage. One says use as low pressure as possible to
minimize damage to the tubing.....the other says to use as high
pressure as possible to intentionally blast thru and expose weak (thin
from internal rust) spots, which can then be cut out and new tubing
spliced/welded in. And of course, never blast thin sheet metal (steel
or aluminum) as the frictional heat can warp the sheet metal .
Chemical stripper works better for sheet metal.

[Bob]

On Jun 13, 1:21*pm, Dan > wrote:

>
> * *I didn't mean to imply the Navy uses riveted hulls. I had just
> watched a show on television about Titanic and I was thinking of the
> rivets used in that era.
> --------------------------------------------------------------------------

There's still a few structural steel applications that call for rivets
instead of welding. But it's usually on repair work or modifications
to a riveted structure -- lots of railroad bridges came as 'kits' and
quite a few were riveted. But some are bolted together, often with
Sher-Lock (sp?) type bolts

-R.S.Hoover

[Stealth Pilot[_2_]]

On Sat, 13 Jun 2009 16:44:50 -0700 (PDT), rckchp >
wrote:

>On Jun 12, 3:56*pm, Michael Horowitz > wrote:
>> 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
>
>I sandblast for my living (cemetery lettering) and the most common
>misconception is more pressure strips/cleans faster.....when actually
>the more CFM (cubic feet per minute) is what works best.

true but all you have is a pressure gauge and whatever the compressor
delivers. usually what you get with a pump system that deliveres
slower than you are using it, is a reducing pressure and eventually
the need to wait for a pump up. with the bigger pumps what you notice
is that the compressor just keeps on delivering at whatever pressure
you dial up.

150psi will remove rust, paint etc almost completely in a single pass.
100 psi will remove slowly
80 psi is a very gentle action if at all.

also you can moderate the "cutting" action (if you'd call it that) by
angling the gun off perpendicular to the job.

blasting thin metal distorts the sheet all right. the surface closest
to the gun is peened into compression and this causes the sheet to
grow toward you. (aluminium sheet -thats a good use for 60psi blasting
and a very gentle touch)




> In the past
>when I was an active EAA member I did a few blast jobs on Cub fuselage
>structures. I use a 100 CFM compressor, such as used by utility crews
>to run jackhammers, etc. Most tool rental places have 85-185 CFM
>machines for rent....anything from 50 CFM up will work fine.
>
>There are two "schools of thought" about how much pressure to use when
>doing steel tube fuselage. One says use as low pressure as possible to
>minimize damage to the tubing.....the other says to use as high
>pressure as possible to intentionally blast thru and expose weak (thin
>from internal rust) spots, which can then be cut out and new tubing
>spliced/welded in. And of course, never blast thin sheet metal (steel
>or aluminum) as the frictional heat can warp the sheet metal .
>Chemical stripper works better for sheet metal.