Sandblasting media

rob love · #1 08-07-09, 20:45

With regard to the window getting sandblasted, I have gone to a different solution. I just let it get blasted. The plastic frostshields to protect it run about $3 each, and get sand etched rather quickly. Instead, I just replace the glass every few months. Princess used to have them for just $8 each. I had a small stack of them, although I also notice that princess seems to have quit stocking the replacement glass.

WRT the air exhaust, there are actually two ports on the cabinet. The one on the left would be for fresh air intake, while the one at the back of the cabinet will be for exhaust. I used to use a modified fan for the exhausting, but the dust was destroying the fan annually. Without the negative air pressure, you will not see anything.

WRT all the various environmentally friendly and health conscious blast media, the problem with any of it is that the end result of blasting adds things like the lead based paint, rust, possible asbestos, and whatever else is present on the item being sandblasted. So in the end, anything used must be considered toxic. Maybe just less toxic. With a good vent fan on your cabinet, you will have no need for masks or supplied breathing air. The cabinet will be in a state of negative pressure, so nothing will escape it.

cletrac (RIP) · #2 08-07-09, 21:04

When it comes to protecting a vision port the best thing I've found is a piece os Saran Wrap or the like. The sand bounces off without making a mark.
I agree with Rob on the media bit. Sand is cheap and you don't want to breathe the dust off any of it. This thread http://www.class-five.com/~mlu/forum...t=sandblasting
shows the cabinet I made.

George McKenzie · #3 09-07-09, 07:18

When I am beadblasting I could do it with a white shirt and tie There is no dust what so ever .The only time I use a mask is when I put things in or out . My window is 18"x30" and is plastic so I cover it with the Princess Auto material and I didn't think it was very expensive and will do quit a bit of blasting before I have to change it .

Jordan Baker · #4 16-07-09, 06:25

OK so I got the cabinet all setup today and finished assembling it. I used a silicone adhesive to seal all the panels but still found a few spots that I missed. As for the media I chose. I just went with the glass/sand for now.

My next problem is the compressor. The little one we have just wont cut it and I fear that I will wear it out rather quickly. I was going to check out Home Depot tomorrow to see what they had. Any suggestions.

Lynn Eades · #5 16-07-09, 09:37

The air consumption depends on the type of gun and the jet in it.
Compressors are rated by the FAD (free air delivery) in cu. feet per minute.
It's hard to get apples for apples, but go for the biggest one you can afford.
A large receiver (tank) will let you blast longer before the pressure drops off, but it also means that you have to wait longer to pump up again, if the pump is to small.
Keeping the media (sand) dry is very important to having it flow freely, and work well.
LASTLY, but MOST IMPORTANT. A young fella like you needs to be very careful when it comes to dust, and when blasting it is hard to avoid breathing at least some of it, sometimes. Because of this I would seriously reccommend using a media that is NOT silica based. Silicosis leads to lung cancer. Buy some garnet or other suitable media, and a respirator. They're cheap compared to maybe cutting 20 years off your life.

rob love · #6 16-07-09, 15:17

I am not even sure you will find a compressor big enough at home depot. Seems like what they call a 5 hp has a motor about the size of a household clothes dryer, and the results to match. I drilled out the passage in my sandblast gun to allow more flow mind you, and get the results of a commercial sandblaster out of it.

As to air supply; I have an older 2 hp (with one of those massive old style 70 pound electric motors) and will run one of those wheelbarrow type gas compressors in tandem with it when I sandblast. I am using one of the princess auto made gas powered compressors, somewhere around the 9 horsepower range. It will also keep up enough air to use a commercial spray gun. Once I get electricity into my new shop, I will hook up my 2 stage 7-1/2 horsepower compressor, which I got from a auto dealership closeout.

I will echo Lynn's recommendation to avoid that dust. I'll snap a photo of my exhaust system when I get out to the shop later. It is the best $120 you will spend, as it removes all dust from the cabinet, dumping it outside.

Bob Carriere · #7 28-07-09, 22:11

Oure expereince at the barn has been with the Princess cabinet..... which once assembled needs to be glued shut and/or taped.

I choose at the outset to use aluminum oxide.....expensive but lasts a long time and cuts fast. Sandblasting cabinet is USELESS unless you hookup a shop vac to create a neg. pressure....... I use a 5 gal. metal can to catch osme of the heavier dust before it enters the shop vac...... buy a shop vac with a written 5 year wrranty and expect to replace every year...... no matter what you do the aluminum oxide will kill the blower/motor bearings.

On a regular basis dump the blasign media as it gets full of large flakes that will plug the suction tube....... nozzles also need to be replaced as the wear to a large orifice and reduce your cutting capacity.

On the glass...... I made a new wooden frame held by wooden screews which are easier to remove to replace the plastic lining. Have a set of spare rubber gloves.... you will cut them or wear holes in them at themost unopportune time..... like late on a weekend and Princess is closed....

Keeping a good source of lights inside is also a challenge.... I have taken to junking them regularly when they get tooooo pitted to let light out....I have opted for under the counter lights from Home depot that runs on 12 volts....cheap and easy to replace.

Finally the "kompressor"....... like other manly things bigger is better.

Check out the specified C.F.M. of the cabinet as listed in the Princess catalogue...... you do not need high pressure but high volume.... youmight get by with a high CFM 7 1/2 HP..... as large a tank as you can find for the reasons given above...... you do not necessarily need a two stage compressor....... but they do come in handy to run a 3/4 inch impact for those stubborn rims studs...... requires 125/150 psi..... 900 pounds of torque and we still need touse the hot wrench to mellow the nuts to some mobility..

I am using a 10HP Princess running on single phase 60 amps on start up..... when it kicks in the lights dim in the village..... 120 gal. tank rated at 33 CFM at 100 psi.....

Caution..... whatever size you buy..... install it as far away as you can... they are noisy...... I had no previous expereince and installed mine in the attic of the barn...... never regretted the efforts to get it up there..... if you are in attic looking for parts and the sucker goes on...... hope your head is not under a low part of the ceiling.......they are as noisy as a Harley Dee.

Be prepared to drain the water out of the tank regularly.... so make provision for easy access to the drain plug/valve...... a good 3/4 in. ball valve from Princess will do the trick.... and a hose section to shoot the water in a desireable direction....... one litre of water at a time coming out at 150 psi really fogs up quickly......including oil from the compressor....

One final note..... when you pipe in your air lines from a remote location to your work site....... consider installing a special flexible section to you 1 inch steel delivery line..... it will reduce noise and vibration to the steel line.... and use a water trap in addition to draining the tank.

Now you are set for a blow job.....

my 5 cents worth

BooBee

Snowy · #8 29-07-09, 04:42

Quote:

Originally Posted by rob love

WRT the air exhaust, there are actually two ports on the cabinet. The one on the left would be for fresh air intake, while the one at the back of the cabinet will be for exhaust. I used to use a modified fan for the exhausting, but the dust was destroying the fan annually. Without the negative air pressure, you will not see anything.

I'm working on improving my el-cheapo sandblasting cabinet at the moment and am thinking that an extraction fan could benefit from a cyclonic seperator as well as a fine particle filter. Some vacuum cleaners use this method and they seem simple enough to make after seeing this article on Hack-a-Day a few days ago: http://hackaday.com/2009/07/19/cyclo...st-seperation/
Principle of operation: http://en.wikipedia.org/wiki/Cyclonic_separation

Steve.

Pedr · #9 29-07-09, 19:32

Thanks Snowy,

That's really answered all my questions. This is going to be the answer to my problems. Have killed a couple of vac's already and hate having to empty and clean dust extraction system every hour.

Spoke to my ol' man ( who's a mechanical engineer specialising in designing and building special purpose machinery ) asked about using a cyclone to remove glass bead dust from my cabinet to allow reuse of media after cleaning, He said that it wouldn't be possible because material is usually blown into a cyclone ( he's been working in the mining and paper pulp industries, the first where they blow air down the drill hole to reclaim the drill castings collected at the cyclone and the second where the waste passes through the fan which allows it to be smashed into smaller pieces then blows it into the cyclone and onto a compactor bin for recycling through the pulp mill again. ) Anyway, this proves that what I was thinking about will infact work.

I like the features of the Clear Vu CV06, in that it has the sprial ramp on the dust intake, but I love the thought and design that has gone into the Oneida Dust Deputy, especially the larger unit, but the cost makes them a little prohibative and that they haven't been used on blasting media only saw dusts. After watching all of the Youtube video presentations of these cyclonic separator systems, I think that ALL vacuums should have one of these.

So, once again, thanks to Snowy for this tip.

Pedr

cantankrs · #10 30-07-09, 11:48

Hi All,

Seeing Snowy and Pedr's posts forces me to finally stop and mention Bill Pentz's hard working efforts to help guys like us save our lungs. http://billpentz.com/woodworking/Cyclone/index.cfm
I'm pretty sure he has details on how to build your own cyclone as big as you need and with the blower on the top so only 'fines' travel thru the blower.
I haven't tried building one yet but its on my list of things to do before I need it so I won't die early.

If you use his info then he sounds like a bloke worthy of a donation.
And I'm not related to the chap in any way.

Regards

Alex

Bob Carriere · #11 31-07-09, 19:59

I have installed a 5 gallon metal can with a store bought plastic cover that has a molded angled intake and outlet, which they claim, will spinf the air flow....... it collects a lot of solids...... inclusing a lot of the blasting media(aluminum oxide)........... media is so dusty fine that we discard as resuing it would just be a waste......It has prolongued the life of the shop vac to at least twice as long as before...(over a year now).... and the negative pressure of the cabinet keeps leaks to a minimum so a face mask is hardly required.

In answer to Jordan's door leaks....... get yourself a roll of winter foam rubber door sealer at CTC...... get the thin type 1/8 or 1/4 soft foam.... easily installed witht eh self adhesive backing......

I find that turning off the ceiling lamps in the shop reduces glare from the window glass and increases visibility to the inside.

To save our backs and make moving the cabinet easier we built a angle iron floor platform on casters.... raises the hand holes about 6 inches and provides a shelf for the shop vac and 5 gal. can all in one contained unit...

May actually use it this weekend to clean up a doz. or so rear shock steering ball linkages from earlier CMP......now that I bought replacement gloves....

Bob C.

George McKenzie · #12 04-08-09, 06:55

This is what my truck sleeper look's like .No dust ,no leaks .Very portable .My 27 cu ft doesn't run half the time . I use my shop vac with a long hose so I can put it outside the shop so it is quiet .and if there is dust comming out of the vac it doesn't matter as the vac is outside .

maple_leaf_eh · #13 10-08-09, 03:58

Are you sure you didn't steal that from some hospital nursery ward?

The gun community rarely sandblasts any gun parts, but they do need to vibrate and clean cartridge cases. The standard media include walnut shell pieces, corn cob pieces, apricot pit pieces and white rice. The latter surprised me, but anything that is hard surfaced and slightly textured seems to be required. Somebody lately found a supplier of hard plastic beads at his wife's craft supply store. He claims they work like a charm. I don't know how any of this is going to flow through a nozzle, but it is the thought that counts.

Cleaning regimes for cartridge case tumblers usually include some form of chemical rejuvinator and household dryer softener sheets. The mesh turns filthy and the media gets cleaner.