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Thread: media/pressure blasting set-up help?

  1. #1
    xl97 is offline New User
    Join Date
    Dec 2008

    Default media/pressure blasting set-up help?

    I have a small Harbor Freight pressure/media blaster...

    I believe it is this one:
    - Harbor Freight Tools - Quality Tools at the Lowest Prices

    I have no real experience with blasting before...

    but took some 'black magic' medium..threw it in the blaster...

    hooked it up to my compressor..and started to see how things works stripping some old paint/rust off some old parts..

    I found that the medium seems to 'spit' from the nozzle..instead of a constant 'stream' of abbrasive... and at just seems to FALL out of the nozzle end when open..and I point it down.

    is this normal? what can I do to get a more useful pressure blaster? with consistent pressure/stream... and the media staying in the blaster until ready.. (not falling out of the deadman nozzle)..

    am I using to small of a medium? (I didnt think it mattered)

    is the blaster just a POS? (its used)


  2. #2
    CarWiz's Avatar
    CarWiz is offline Metal Finishing Guru
    Join Date
    Sep 2005
    South Texas

    Default Re: media/pressure blasting set-up help?

    Download the manual and read page 10. It describes how to adjust flow and pressure. All the pressure blasters require fine tuning. It's a balance between media flow and air flow and needs to be adjusted with each type of media. And dry air is paramount!

    Pulsing indicates too much media flow but this can occur, and is normal, right after filling. You need run it for a few seconds to clear the manifold and hose then adjust the media and/or air flow until you have a steady blast. You should just barely see the media blowing from the tip. Sort of like smoke. You don't want a solid stream of media. Practice and you'll see the difference it makes between flow rates.

  3. #3
    XK120DHC is offline Experienced Metal Finisher
    Join Date
    Jul 2004
    Texas! Is there anyplace else?

    Default Re: media/pressure blasting set-up help?

    Yeah, what CarWiz said. ;-}
    Also, you didn't mention what size air compressor you are using. A Pressure Pot blaster consumes a huge quantity of air (CFM). If your air compressor is underpowered, in both horsepower and air output, no blaster will work right. The manual (Wiz linked), possibly somewhere on the blaster and on your air compressor the CFM requirement and output should be listed. Your Air Comp output needs to be more than the blaster's consumption rate.. otherwise you'll be standing around waiting for your compressor to "catch-up". The Air Comp running non-stop is Not Good!
    I have a 100lb Pressure Pot Blaster and a commercial Five Horse, twin cylinder, dual stage, 80gal tank Air Comp. I blast everything on a car/motorcycle from the chassis, sheet-metal, all the way down to the nuts and bolts.
    As CarWiz noted, you have adjustments for both the "volume" of Air as well as the media. This is NOT a "Set It And Forget It" situation.. as the heat of the air increases, the humidity increases/decreases, air density, etc. change, you WILL need to "tweak" the pressure pot blaster.
    About the Media.. You can spend a lot of money on fancy named media, but good old "Blasting Sand" is, in my opinion, the best overall stuff you can get (search out a "Contractor Supply" in your town.. I buy mine for about $8/100lb bag). You DO NOT want "play sand" nor concrete mix sand.. the grit is not uniform and will clog your nozzle at a minimum and, at worst, your output hose! I use "#4 Blasting Sand" and I reuse it (after filtering it, of course) about five times.. by then it's more dust than sand. The "#4" (here in Ft. Worth, Texas) is the "finest" (smallest) grit you can get.. It's great for frames of cars, or "hard parts" like suspension items. It's too aggressive for more delicate items until it's been reused a couple of times. Now, having said that, I don't have a problem using "specialized media", like ground corncob, walnut shells, etc. if that produces the results you are after.
    It should go without saying, you WILL need to wear a respirator when blasting sand.. The dust given off will kill you (eventually).. Avoid the paper "dusk masks", they are useless. Use a full-on painter's respirator with standard cartridge filters and "dust caps" over those.. helps keep the cartridges cleaner, longer. If you do electroplating, you can swap the cartridges for "Acid Gas" cartridges.. you should be useing them, as well..
    Didn't mean to preach.. hope I helped you some.

  4. #4
    maahi is offline New User
    Join Date
    Nov 2009

    Default Re: media/pressure blasting set-up help?

    Thank you for the information.

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