From: ygmir (ygmir@onemain.com)
Date: Sat Mar 30 2002 - 19:01:04 PST
Hi John,
I sandblast for a living, I make tombstones (ok, laugh if you all must).
The h.p. isn't as important as the c.f.m. Usually there is a correlation,
but that also depends on if it is a rotary or piston compressor, and if you
are referring to electric motor or combustion engine.
Reumilin makes a very good sandblast generator, but there are many
manufacturers, you can even make one yourself if you are handy with plumbing
and a little welding, and understand the dangers of air pressure and
vessels.......
It takes about 70 cfm at 100 psi to run a 1/8" nozzle orifice, using a
pressure pot style blast generator and still get about 100 psi at the tip.
As the nozzle orifice diameter increases through wear, you either need more
cfm, or the output pressure will drop. Much below 50 psi at the tip won't
cut paint or rust very well. Also, the larger, heavier and more angular
(sharp) the media used, the faster and more aggressive the cutting. You can
use from talcum powder to pea gravel, it just depends on what you are doing
and how big your machines are...........
I use a 20/30 grit media and a 1/8 inch nozzle, and it cuts very well. Using
river sand is cheap, but the size parameters of some manufacturers can vary
widely (leading to plugging problems, and the need to re-screen), and it is
fairly light. There are several abrasive medias and manufacturers available,
just search under "sandblast media". You can use copper smelting slag,
garnet sand (my favorite, for cutting and it can be recycled well), silica
sand (higher health hazard associated, but good cutting properties), steel
shot, and a variety of others.
Sometimes if you have a big project to do, and not many of them, it is
advisable to rent a 150cfm compressor and sandblast pot with about a 1/4"
nozzle from a local rental yard and really blow through the job. It is
somewhat expensive, but very much faster than smaller units that would serve
you very well for spot cleaning and individual parts and panels.
Also, remember humidity will cause rust to develop very quickly. If you can
spray primer with an hour of cleaning, it will really stick because with
most steels in most conditions, it is still "virgin" for an hour or so, as I
understand metallurgy, and since there will be no surface oxidation to speak
of yet, the paint gets not only its usual adhesive properties, but some
electrical bonding, too.
I'm sure I have left something out, and hope I have been accurate in my
info. If not, maybe someone else can correct me, cause I'd like the correct
info, and have no ego when it comes to what's right............
Good luck,
Henry
----- Original Message -----
From: "Doyle, John D" <JDoyle@framatech.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Saturday, March 30, 2002 3:10 PM
Subject: [MV] sand blasting
>
> 2 weeks ago I bought a $140 sandblaster to do some
> work on my '51 M37 and '62 WM300. I should've known
> from reading the directions that were in "chinglish"
> that it wasn't worth fooling with. I just took it
> back today and am again on the hunt for a sandblaster
> to do some middle-of-the-road stripping of frames,
> panels, bumpers, ...
>
> I figure with this crowd, there would be some ideas
> on THE sandblaster (make/model/capacity/...) to have.
>
> Currently I have a 5.5hp, 30g compressor. If that
> needs to be bigger, what do I need to get for that that
> I can still move around if I have to? It can be
> semi-stationary, preferably 120vac, althought 220vac
> might work if absolutely necessary.
>
> What is the best media to blast stuff with?
>
> Thanks,
> JD
>
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