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Thread: Advice on a serious blaster

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    FigureLLC's Avatar
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    Default Advice on a serious blaster

    Argh. I hate trying to figure out blasting. I'm in the market for a new bigger and badder blaster, and could use some pointers for those of you who have serious set ups.

    I have a 10hp/120gal compressor, and I know this is a huge limitation for production blasting... Right now blasting space within a cabinet is a bigger concern than the time it's taking me to blast. But, I also would like to have something that can grow with me as I eventually upgrade the air systemicon to more CFM. So here are my biggest questions:

    1) I know pressure blasters are supposed to be more efficient than siphon. They also use a lot more air. Will 40CFM of pressure blasting be faster than 40CFM of siphon blasting?

    2) Anyone have experience with a pressure blast cabinet? I've seen all the talk (without any real meat to it) about PA blasters. Unless it's far superior than a real pressure blaster, I'd prefer to buy something rather than build it. The known disadvantages to pressure cabinets are A) you have to change over the media, and B) they're more expensive. Anything else?

    3) Is there any real advantage to a blast room over a sufficiently-sized blast cabinet? I'd really hate to eat up valuable shop space at this point with a blast room. Plus with the room, blaster, dust collector, and PPE costs, I think it'd be pretty expensive to get into.

    4) Any suggestions for companies that build industrial blasters? Good or bad? I was looking at some Bad Boy Blasters, and first noticed their guns looked remarkably similar to the HF guns. Then I noticed their one cabinet IS the HF cabinet, except theirs is blue and $1000 instead of the $600 or whatever I paid for mine.
    Len
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  2. #2
    XK120DHC is offline Experienced Metal Finisher
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    Default Re: Advice on a serious blaster

    Quote Originally Posted by FigureLLC View Post
    Argh. I hate trying to figure out blasting. I'm in the market for a new bigger and badder blaster, and could use some pointers for those of you who have serious set ups.

    I have a 10hp/120gal compressor, and I know this is a huge limitation for production blasting... Right now blasting space within a cabinet is a bigger concern than the time it's taking me to blast. But, I also would like to have something that can grow with me as I eventually upgrade the air systemicon to more CFM. So here are my biggest questions:

    1) I know pressure blasters are supposed to be more efficient than siphon. They also use a lot more air. Will 40CFM of pressure blasting be faster than 40CFM of siphon blasting?

    2) Anyone have experience with a pressure blast cabinet? I've seen all the talk (without any real meat to it) about PA blasters. Unless it's far superior than a real pressure blaster, I'd prefer to buy something rather than build it. The known disadvantages to pressure cabinets are A) you have to change over the media, and B) they're more expensive. Anything else?

    3) Is there any real advantage to a blast room over a sufficiently-sized blast cabinet? I'd really hate to eat up valuable shop space at this point with a blast room. Plus with the room, blaster, dust collector, and PPE costs, I think it'd be pretty expensive to get into.

    4) Any suggestions for companies that build industrial blasters? Good or bad? I was looking at some Bad Boy Blasters, and first noticed their guns looked remarkably similar to the HF guns. Then I noticed their one cabinet IS the HF cabinet, except theirs is blue and $1000 instead of the $600 or whatever I paid for mine.
    LLC;
    I've been sandblasting antique & classic cars and parts professionally for the better part of thirty-four years and I believe I can properly advise you..

    Question #1 a 10hp, 120gal set-up.. Are you going to be sandblasting Aircraft carriers? I have, and effectively use a 5hp, 60gal (twin cyl, two stage) set-up and my pressure blaster has never "out run" the compressor. In other words, my compressor will "cycle" off and on during constant blasting.
    Siphon Feed blasters are NOT worth the powder to blow them up! Most require 90psi just to work, and the "quality" of their "work" is laughable.. A Pressure Pot blaster, on the other hand, can work very effectively at 50psi (I also dial it down to 40psi for the more delicate items!), remove the toughest baked-on enamel & rust and NOT "heat-warp*" the sheet-metal (*If you "bore-in" on one spot, you WILL warp the metal and probably cut a hole in it!)
    Question #2. I have a cheepie H-F Blast Cabinet, I use my Pressure Blaster in it, as well. The small size of the cabinet is its only limitation, but I bought it for small parts and it works great.. After I run about 50lbs of sand into the cabinet, I "pull the plug" at the bottom of the unit, drain the sand and reuse it. (in reusing the sand, it gets beat finer and finer, great for putting a "satin finish" on interior garnish moldings on '50's era cars!) I paid about fifty bucks for the cabinet nearly ten years ago. I've replaced the viewing window once (I tapeicon-on clear 0.010" Lexan sheets to protect the inside of the viewing window.. Each Lexan sheet lasts about an hour.. and so does fifty pounds of sand) and I've replaced the "floodlight" bulb once.
    I've never used anything but "#4 Blasting Sand" for both "open" and cabinet blasting.. Where is it written that you "have" to change media when blasting in a cabinet?
    I have the plans for a PA Blaster.. If you can't afford a decent quality 100lb Pressure blaster, then maybe using the PA design on your siphon-feed blaster would be an improvement.. Given that I use "Low Pressure, Low Angle" blasting techniques effectively, the PA is not for me..
    Question #3. The Advantage to a "Blasting Room" is a simple one.. it allows one to "recycle" the blasting sand.. There is method to this madness.. As noted above, I use #4 Blasting Sand.. it is now the "finest" grit available in north-central Texas.. thirty years ago I used #5, it was discontinued. I buy 20 100lb bags when I ready to blast a car and all it's bits and pieces.. With the "new" sand, I blast the Chassis (frame) and all "hard parts" like suspension, steering rods, etc. I refill my pressure blaster with a new bag of sand until all these "hard parts" are done.. Then I sweep up the sand on the floor, strain it (thru a mesh screen) and put it in a clean barrel (used only for sand). I then take the "next batch" of parts to be blasted.. not quite as "dense" as the frame, etc. but still "heavy", and I use the "once used" sand. I continue reusing a previously used batch of sand on each "lighter gauge" batch of parts. By the time I blasting with "powder", I'm blasting the body, doors, hood (all the sheet-metal) of the car. I should also note that immediately after each "batch" of car parts is done, it is blown off, wiped down with a Degreaser, tacked-off then shot with an epoxy primer. No rust is allowed to form.
    My "blast room" is a corner of my shop that is "walled in" with heavy mil clear plastic sheeting (I buy it in 100' rolls). The "walls" are all clear plastic and one continuous piece, the "ceiling" laps over the walls. The whole mess it attached to the ceiling rafters with 1x2's and wood screws. Allows for easy install and take-down. I use 2x4's to hold down the bottom of the walls. It goes without saying, but a respirator (not a dust mask) is a MUST when doing this.. also guard against dehydration, as well (the temp can go over 135 in this plastic enclosure during a "normal" Texas summer!).
    Lastly, Question #4. I bought my Pressure Pot Sand Blaster at an automotive swap-meet from an Oklahoma fellow who, I believe, built these units in his garage. Seems I gave a couple hundred dollars for it, but I got a longer than "standard" blast hose (helps in moving around a car body on a rotisserie). It has a 100lb capacity-- 110 if you "stuff it" full-- (that's about 60-90 minutes of blast time), replaceable ceramic nozzles (about $5 last time I bought them). I bought this unit just about twenty years ago. If you are familiar with "TIP" blasters, it's made pretty much the same way.
    Bottom line is, you don't need "bigger and badder".. Sandblasting is an Art, not a Demolition Derby.. a light touch, finesse and "quality time" will result in a high quality job!
    I hope this answered your questions as well as clearing-up your misconceptions about sandblasting..
    Last edited by XK120DHC; 03-05-2009 at 05:10 PM.
    Charles

  3. #3
    Brintiff is offline Amateur Metal Finisher
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    Default Re: Advice on a serious blaster

    A pressure assisted blaster is the best of both worlds, low blast pressure means less air than a siphon and no clogs or spurts. Do a search for PA Blaster, the website is kinda crappy but the product is great. I built one from the plans and it does everything they claim it does. By buying the plans you get access to the yahoo group which has tons of help.

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    FigureLLC's Avatar
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    Default Re: Advice on a serious blaster

    wow, charles... i had missed your reply. thanks! i know a lot of care has to be taken with sheet metal, but i don't do a lot of sheet metal. and it sounds like from what i've read since my post and what you have told me, that the lack of production is indeed from using a siphon blaster. a couple weeks ago i bought a big used blast-it-all cabinet. it won't do a better job blasting, but i can do bigger stuff, actually move stuff i do a lot like bicycle frames around in there, and it's got a real deal dust collector so i can see my work (not to mention free up our shop vac). i'll eventually try out a pressure blaster set up. blast-it-all sells a pressure blaster cabinet upgrade for $2000 or 3000, i don't recall which. i know it's expensive, but it's got fully automatic refills, and if it's built like the used cabinet i bought, it's bullet-proof and well-thought-out. i've still got lots of learning to do on blasting.
    Len
    Figure Finishing
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    FigureLLC's Avatar
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    Default Re: Advice on a serious blaster

    i dunno. i've been gnawing on this for a few hours, and i'm still not sure. i read that every time you double the cfm, you third the blast time. so if it takes an hour with 40cfm (~10hp), it'd take 20min with 80cfm (~20hp). i never got the impression that cranking the pressure up really helped. kinda like washing a car with a pressure washer or a fire hose. one's high-pressure/low-volume, the other's low-pressure/high-volume and it's clear which would win.

    by "change over" media, i meant refill the pot.

    oh, what is #4 sand? surely it's not 4 mesh. that'd be like 1/4" pebbles, no? and do you really use sand? sounds risky even with a respirator.
    Len
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    CarWiz's Avatar
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    Default Re: Advice on a serious blaster

    A higher volume of air at any pressure is going to allow you to move more abrasive through a gun (tip). More abrasive means faster cutting. I have 160CFM available but because I'm using 3/8" lines on my tank and 1/2" out-feed with a 3/16 - 1/4" tips, I'm probably drawing less than 35CFM. The engine that powers my compressor never goes over about 1600rpm out of around 2400rpm available. In fact, it's almost in constant bypass. The 1600rpm is basically it's "idle" speed. I went the shop-built route on the 300lb pressurized media tank. I use a separate room off the shop as a "blast cabinet". The room is 10' x 16' with a 7' ceiling. I also use a forced air breathing systemicon and wear a full coverage suit.

    What I meant by "more abrasive means faster cutting" does not mean a constant stream of media. When my blaster is tuned to the abrasive, you can barely see it coming out. Like I mentioned in another thread, it will strip a 15" factory wheel in about 10 minutes or less. That's complete and getting all the details. It strips paint in nothing flat. Heavy rust or old Bondo takes a little longer but still much faster than manual methods. A couple of gallons of gas and 300lbs of media will nearly strip a whole car. I think if you went the 30-40CFM route, you wouldn't regret it. When I look back at blasting with my old setup (5hp/17cfm), it was drudgery--Slow with small tips. I still use it for small items but you just can't beat CFM and a pressurized media tank for getting work done.

    I'm always on the lookout for air compressor tanks. They're easy to convert to media tanks and having a couple makes swapping media a snap. I especially like the blown-up airless compressors. They're cheap and have a good tank! All cabinets have a drain on the bottom so even with a cabinet, it's not all that bad to change media. Or recover it to put back into the pressure tank.
    Last edited by CarWiz; 03-25-2009 at 01:23 AM.

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    XK120DHC is offline Experienced Metal Finisher
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    Default Re: Advice on a serious blaster

    Quote Originally Posted by FigureLLC View Post
    i dunno. i've been gnawing on this for a few hours, and i'm still not sure. i read that every time you double the cfm, you third the blast time. so if it takes an hour with 40cfm (~10hp), it'd take 20min with 80cfm (~20hp). i never got the impression that cranking the pressure up really helped. kinda like washing a car with a pressure washer or a fire hose. one's high-pressure/low-volume, the other's low-pressure/high-volume and it's clear which would win.

    by "change over" media, i meant refill the pot.

    oh, what is #4 sand? surely it's not 4 mesh. that'd be like 1/4" pebbles, no? and do you really use sand? sounds risky even with a respirator.
    Len;
    Sorry to be so long in getting back to this thread.. I sorta "misplaced" it..
    In re-reading what I originally wrote, I failed to mention that my Five Horse, Two Stage 60gal compressor it set to produce a "max pressure" of about 130PSI.
    I have two "outlets" on the tank.. one 1/2 "Black Pipe" run that it for my everyday air tools, paint guns (conventional & HVLP), DA & Straight-line sanders, 1/2" & 3/8" Impact Guns, Air Ratchet, "Jitter gunicon", die grinders (I use three different types) as well as supplying "air" to the agitators in my electroplating tanks and powdercoating gun. The output pressure of the 1/2" line is "generally set" (at the regulator/filter) to 110PSI. The 3/4" line is primarily for the Pressure Pot Sandblaster. The Regulator (and filter) on the wall (primary output) is set to 60PSI (occassionally higher for "other than sandblasting" use), an air hose runs to the pressure blaster via "quick disconnects", the regulator and filter AT the pressure blaster is set to 50PSI on average.. depending on what I'm blasting, I might lower the pressure to 40.. any lower than that is just slow going ;-}
    On the "Grit Size".. Don't get me to lying, the sand is bagged in Texas, sold in Fort Worth and the grit "ranges" are #1 thru #4 plus "Silica Sand" (which is a "finer" grit than the #4.. this is the "white ash tray sand" you use to see in the "butt pots" in airports, finer hotel lobbies, etc... With respect to silicosis, "Silica Sand" is the worst).. On the health/breathing issue, I agree, sandblasting IS dangerous, but using a quality respirator fitted with "Organic" cartridges and "pre-filters", you have about the best protection short of a "Outside Air Breathing Rig" (can you say "Serious Bucks"?).. And, Yes, I really use sand.. I have found that nothing else, no "whiz-bang media" will get into and clean the "pits" better than good ol' real sand. I have not experienced any breathing (cough) problems (chough, hack) in the thirty (cough, hack, hack) odd years I've been (cough, cough, hack, gag, hack, spit out the blood) doing this.. Seriously, I breathe just fine. It is, however, damned important that your respirator fit your face properly and is "snugged up" to prevent any dust getting but the "seal".. Same is said when painting with today's "chemistry set" paint systems (some contain isocyinates.. bad chit!)
    Going back to the first part of your post, about "doubling" the CFM.. That was not my post, but I can say, your "CFM" is based on the combination of the compressor's motor, RPM of same, type of compressor (single stage, two stage, single cylinder, twin cylinder, etc.) at a specific output air pressure. Like oil pressure on an engine.. It can be all over the gauge, but the "factory" uses a set RPM to produce a certain PSI. If the oil pressure isn't "that", then there are "problems" inside the engine. Point being, if you have a Three Horse motor running a small two cylinder, single stage compressor, the CFM is going to be low, changing pullys is not going to help a bit.. It'd be like taking a Ford 292 and trying to make it into a 426 Side Oiler! It just ain't gonna happen!
    Sandblasting, like racing have a same rule.. Nothing Beats Cubic Inches! For "effective" sandblasting, 19CFM at 90PSI is a "minimum" one should have.
    Your "10PH/120 Gal compressor" probably cranks out well over 19CFM without breathing hard.. At 40/50 PSI, the compressor will pump-up, cycle off and you'll probably blast for five minutes, maybe longer before the Comp cycles back on (assuming you are using a "Pressure Pot" Blaster).. If you are using a Syphon Feed, well, let's just say you are "blowing" in the wind".
    Again, I apologize for not following-up on this thread..
    Charles

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    Grogel is offline New User
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    Default Re: Advice on a serious blaster

    Len,

    I just signed up here because of your question. I have work in a metal blasting and deburring shop for 18 years.

    Looking at the website for your shop, it looks to me like you are ready for a real blast cabinet or a shop to do the work for you.

    IMHO the badboy blaster is a advanced hobbyist tool and not a production machine. Nothing wrong with that!!

    I have both Empire, zero and Gamm pressure blasters in my shop. Pressure blasters are not only faster, but can be used to blast at lower pressures than suction blasters when set up properly. With proper dust collection and a reclaim unit, use media and trash are constantly being removed.

    It does take longer to change media in a pressure unit, I like to keep them dedicated to a media so that isnt a issue.

    I also have empire profinnish pressure blasters in the shop. They are a little slower for production because they dont move as much media. They also have reclaimers and dust collectors to take out trash and broken down media.

    The nice thing is that they can be changed from one media to another with ease and take a smaller charge of media to get started.

    This means I can keep costs down when a customer wants a small number of parts blasted in a media that I dont keep in a machine all the time, and I can keep smaller amounts of specialty media on hand for special jobs.


    In my suction machines I run 5/16 nozzles and need 19 cfm for 40 psi and 34 cfm for 80 psi but those cfm numbers drop to 12@40 and 21@80 with a 1/4 inch nozzle.

    in the pressure machines I use 3/16 nozzle wich takes 22 cfm @ 40psi and 38 cfm@ 80 psi

    I dont sell machines so I have nothing to gain but If I where you I would contact a empire dist. I would also call around to the used equipment dealers in your area. Lots of used blast machines out there.

    Gary

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    FigureLLC's Avatar
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    Default Re: Advice on a serious blaster

    Thanks Gary! Good info!
    Len
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    KRISG is offline New User
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    Default Re: Advice on a serious blaster

    We blast alot here. Our big sandblast room 24'/64' uses a 60hp rotary screw putting out 290 cfm. I really wish I had a bigger compressor yet! The more air volume the better.
    We have 6 different Blasters, 3 600# pressure pots and some small ones. We used black beauty 20/40 for heavy iron and rust ex: dump truck bodys, Starblast for aluminum and light steel- Starblast is a very fine pepper light consistancy. We Use Baking powder to strip paint only. In one of the Big room we made our own recycler to reuse the media, using a salt spreader with screens to clean out the media. Starblast works real well in a blast cabinet that recycles. If you have any more questions for me on blasting let me know. Kris

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