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Posted by v8z on June 4, 2007, 11:42 pm
> Anyone got experience with the small sandblasting units like this one
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34202
>
>
> What would be great is to point me at a web site that helps a novice like
me
> figure out how much sand to put in it, how to pressurize it properly and
how
> to set the valve levers when it's in operation. I have followed the
> instructions but it seems to only really work for about three minutes
before
> it loses pressure, I know it's something I'm doing wrong but I don't know
> what. If anyone has experience with these things I would appreciate some
> help.
>
> Harry
>
>
> --
> It is important that students bring a certain ragamuffin, barefoot,
> irreverence to their studies; they are not here to worship what is known,
> but to question it.
> - Jacob Bronowski, 1908 - 1974
>
I have very similar to that and it works great.
First question is did you buy screened, dried sand specifically sold for
sandblasting? This comes in a plastic lined kraft paper bag. You do not
ever want to use "play" sand, or concrete sand. The moisture content is too
high and the size of the grit varies way too much. Either will glog up the
works real fast. Most welding supply places carry the right sand.
Second, does your compressor put out enough CFM at 100 PSI to keep up? To
work effectively, the compressor really needs to be able to put out a LOT of
air. This usually means a min. 5HP compressor with at least a 30 gallon
tank. My 7HP w/ 60gal tank will run the blaster non-stop - the 3 HP / 30gal
I had before made required me to stop and let it catch up. Looks like yours
has a moisture trap onboard - be sure to check / empty it regularly. Also,
be sure to drain your compressor tank regularly too - I installed a 1/4 turn
ball valve in mine to make it easy, figuring the easier it would be, the
more likely I'd do it instead of having to go and get a wrench....
You MUST wear a respirator if using sand as blasting media - the dust it
generates can cause a serious health condition named silicosis
http://en.wikipedia.org/wiki/Silicosis - 'nuff said.
I fill mine about 3/4 full. Brush off the theads for the cap before
installing it. A shot of dry graphite lock lube now and again will keep it
easy to get on and off.
Here's some info on the valves.
First one, closest to inlet is the supply valve. Turn it on to pressurize
the tank.
Second valve is the choke /mixer ( one with gauge at top). Set it to about
half for starters.
The valve at the bottom of the tank adjusts the amount of media feeding into
the blast hose. Start it at 1/4 open or less - you want to run this lean
or you're wasting sand.
Then you're ready to turn on the nozzle valve - be sure to have this one
either fully open, or fully closed - don't run it partially open or you'll
be replacing it very quickly.
If you're blowing lots of air but not enough sand, open the media valve
more.
If you're getting lots of sand, but not enough pressure, close the media
valve some and add more air using the mixer valve.
If you get a clog, sometimes you can clear it by turning off the media valve
and turning the mixing valve to full on - if this doesn't clear it,
completely bleed off all pressure before doing any disassembly.....you might
miss seeing your face in the mirror otherwise.....
One last thing - if you're doing the blasting on a dry, sunny day on a clean
( before starting) driveway, you can sweep up the sand, sift it with sifter
made for blasting sand, and re-use it. But ONLY if its bone dry.
--
V8Z
Chevy V6 powered '66 Datsun Roadster
http://www.mildevco.net/chevypowereddatsuns/
Chevy V8 powered '77 Datsun 280Z
http://www.mildevco.net/chevypowereddatsuns/
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