At 02:16 PM 8/21/98 -0700, you wrote:
>
>So what should I look for in sand blasters? I would much rather have a
>cabinet to contain the sand. But does that limit me too much? In the
>'70s I used a blast cabinet once at the university metal shop. What
>media might a restorer find need for? You know, tell us all.
Ken,
What you described is a typical "syphon" feed system. You can get
the guns for $15 to about $30. The only problem with them is the sand
goes all over the place. What I have done in the past was to go to
my back yard by the back door of my garage. Where the fence (6' privicy
type) formed a corner. I took 2 hook eyes and screwed them into the
posts so that they were about 8 to 10' apart, forming a triangle with
the fence as 2 of the legs. I then tied a rope to the 2 hook eyes and
cliped a large plastic tarp to it with clothes pins. I layed my parts
on the plastic and blasted so that the sand rechoched off and hit the
tap. When the supply tank was empty, I took a small can and scooped
the sand up and recycled it. This saved a lot of sand.
I also have a very nice plastic cabinet from Harbor Freight, about $120.
It is fantastic, however, you will have to make a few mods. The pickup
tube doesn't like to stay in the sand, so I layed the pickkup in the
cabinet drilled a 2 small holes near the bottom of the tube and 2 near
the top. Took some scrap aluminumn and made some "U" clips and pop
riveted it to the case. This has really worked to keep the tube in
the sand.
The nozzels will wear. They cost around $2 each. I suggest that you
keep a couple in reserve.
I have also borrowed a "pressure" plaster from a friend. For doing large
projects this is the way to go. Tip sells them for $300 and up. However,
the one my friend has is about a 50# unit and sells for about $120 to
$150. Again I've seen them in Harbor Freights cat. These really do the
job a lot faster than the plain syphon type. Again the nozzels go pretty
fast. The other problem, is the shutoff valves. If you turn it off,
with the valve you are supposed to use, you'll only get about 10 on/off
cycles before the sand eats a hole in the side of the ball valve. Instead
we turn off the sand feed and then the air. Once everything has stopped,
I disconnect the compressor and crack the air valve back to the compressor
to vent the tank.
With this unit, I usually blast in my drive way. After going through
about 50# of sand (30 + min of blasting) I sweep it into piles, then
using a dustpan, scoop it up and strain it (with some old window screen)
back into the bucket. After I have recovered as much sand as I can, I
fill the tank and start the process over.
John
John T. Blair WA4OHZ email: jblair@exis.net
Va. Beach, Va Phone: (757) 495-8229
48 TR1800 65 Morgan 4/4 Series V
71 Saab Sonett III 75 Bricklin SV1 77 Spitfire
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