Small sandblasting set up

Anyone got experience with the small sandblasting units like this one http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber4202
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,
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Harry, join this forum and ask these folks. They are a nice bunch. Be sure to introduce yourself and tell them what you want to use it for.
http://www.cuttingedgesandcarving.com/forums/index.php
--
Steve Barker





"Harry Palmer" < snipped-for-privacy@nope.com> wrote in message
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sure
HEy Steve
will do and thanks for the heads up
Harry
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"Harry Palmer" wrote...

Not that brand, model or size, but experience nonetheless.

First thing is that you really need a compressor that can keep up. Since you really didn't give any details as far as what type of media, what you are trying to blast, etc., it's kind of hard to give any advice. Different media require different settings, but there are really only two adjustments that need to be made and most times it's a trial and error thing. The valve after the pressure gage is your tank pressure (as it appears in the picture). Heavy media like silica require more pressure and larger nozzles, lighter media like walnut shell require less pressure. There should be a valve at the bottom of the tank, this will control the amount of media that is fed through the nozzle. The goal is to make those adjustments to where the media is barely visible coming out of the nozzle. BTW, you are keeping a constant supply of air to the tank, right?
--
hawgeye



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like
know
what
and
Hey Hawgeye
thanks for the reply. Right now I'm planning on cleaning some interior brick in my attic. It's a knee wall and its covered in about 120 years of Chicago crud. I'm using a media called black beauty http://www.flatrockbagging.com/sand/abrasive.html and the nozzle aperture is about the diameter of a pencil lead, is this too small? I've been using the blaster with the media throttle ( bottom of the tank) open full, so based on your info I'll throttle it back until I can barely make out the stream, thanks for that really great advice. I'm trying to get the compressor to keep a steady pressure of about 60 psi but it keeps dropping off. I'll keep plugging away though.
thanks for your great advice
Harry
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wrote:

Make sure you have a proper source of breathing air, and proper protective cloths. We're talking an OSHA approved resperator here.

IMHO, your air compressor is too small. How big is it? (What is the brand, model and SCFM rating?)
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me
how
before
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.
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V8Z
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http://www.anchitispat.com/ecoventilator.htm
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wrote:

Can your air compressor deliver the 6-25 SCFM needed? I'd guess the real air demand is about 12-15 SCFM which is a *large* compressor.
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me
how
before
Hey peter
I just went upstairs and wrote down the setup details from the setup
the sand blaster is http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumberD762
a.. Abrasive hose: 8 ft. x 3.4'' diameter b.. Valve material: brass c.. Abrasive capacity: 20 lbs. d.. Air consumption: CFM 6-20 @ 125 PSI e.. Air inlet size: 1/4'' NPT AND the compressor is
Air america 5 hp 20 gallon Model f5020 displacement 11.9 cfm 8.8 scfm @ 40 psi 6.9 scfm @ 90 psi
What do you think?
Harry
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wrote:

Compressor is not large enough... <g> That 6-20 CFM on the sand blaster is a bit misleading. The lower value(s) are if you are using it about 10% of the time, basically playing. They give that number so people who have small compressors will still buy it!
Best bet may be to rent a big compressor (I'd suggest one that can do 20 CFM) for the job.
Bottom line: a 7 CMF compressor won't give enough air.
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like
and
know
some
thanks this makes more sense now, I'll go out and rent a bigger one. Thanks for your help.
Harry
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the output of the compressor only dictates how continuous you can blast. Even a little dinky compressor with a big tank will work if you don't mind waiting for it to recover. I have a little itty bitty emglo compressor on top of an old 110 gallon tank, I can do anything I want as long as I don't mind waiting. In the case of blasting, air sanding, etc.
--
Steve Barker





"Harry Palmer" < snipped-for-privacy@nope.com> wrote in message
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one
novice
properly
minutes
don't
thanks for the heads up steve, I'm pretty patient but it's a big loft ( 60 * 30 ft) with a apex at about 14 feet.
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All good suggestions.......
you need a bigger compressor if you want to get serious work done in reasonable amount of time (& not keep waiting for the compressor)
Compressor mfrs overstate their horsepower & cfm numbers....tool mfrs tend to get wide ranges with low ends that just don't work.
The combination results in general disappointment in using air tools. With good tools & the right amount of air....air tool usage is really sweet.
One thing not mentioned is provide for media / debris collection (heavy plastic, drops or cardboard arranged so that all flows into a trough or container)
otherwise you'll generate a real mess in that attic. I set up a "blast booth" (only three sides & a top) to corral the sand & debris (paint).
I re-used the sand by running it through a series of sieves to get the junk out. If you're got real messy stuff to deal with, re-use might not be an option.
cheers Bob
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this
the
appreciate
the
compressor.
setup
using
so
do
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thanks for your great advice bob, I'm taking the advice of my betters and getting an expert in to get this done. I need a lot of other brick related things done so might as well bundle this in with them. Thanks to you and everyone else for helping make this decision.
Harry
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wrote:

Best solution, IMHO! In the end I think you will be happier with the results. Blasting is a pain when dealing with one time jobs. Expensive equipment, major safety issues, and cleanup problems all add up to a 'why bother with this' type situation. Good luck!
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