Blasting cabinet

[Hauk]

It seems that quite a few on this board are using small blaster guns/air erasers for cleaning models etc.

I have aquired one myself, but I am not happy with "shooting in a bucket", and the not so great outdoors is no option in the winter.

So, I am going to build myself a small blasting cabinet. For the cabinet itself I plan to use a plastic storage box with a transparant snap-on lid.
Industrial-grade rubber gloves will be fitted to holes in the front of the box.

But a dustproof box will be a pressure chamber if there is no ventilation in the box.

So what I really need is suggestions for a dust-proof vent. Anyone?

Regards, Hauk

[eTraxx]

Hauk. Interesting to see where you go from here. Here's a link to how someone resolved this using a filter ..

Setting Up A Sandblast System Part 1 .. third Photo/paragraph down the page

[Hauk]

Hauk. Interesting to see where you go from here. Here's a link to how someone resolved this using a filter ..

Thanks for the feedback!
Is that some sort of engine air filter in the picture?
Could that work?

Regards, Hauk

Edit:
I found some small airfilters intended for use on the air intakes on compressor. Could such filters do the trick? All we want to avoid is increased pressure in the box, right? ( I just got images in my head of the lid of the cabinet getting blown off  by a mushroom cloud of baking soda. And then the whole workshop contaminated by the fallout...)

[eTraxx]

Looks to me like the filter from a wet-dry vacuum cleaner.

[RoughboyModelworks]

The engine air filter appears to be a good solution. Perhaps one of the flat engine air filters set into the cabinet wall would work as well or better. Every time you have a joint between components in an air system you introduce another potential leak opportunity. The blast cabinet I use for glass-bead blasting is an old bench-top commercial unit that has a simple ventilator port with very fine screen that does little for dust but does keep some of the excess beads from blasting out of the cabinet. As a result, I keep it in part of the shop where dust is not a critical issue. For proper blasting you also need to attach a vacuum device (simple shop vac) to the cabinet to draw off the dust, especially if you are blasting at high pressure. The inlet to the vacuum needs to be filtered as well to prevent drawing excess quantities of blast media into the vacuum. The standing blast cabinet we had at our motorcycle shop (large enough to hold a motorcycle frame) had a massive vacuum and filter assembly that had to be run with the cabinet in order for it to work. Even then, there was always a dust issue. That's why blast cabinets are usually positioned in areas where dust control is not a significant issue. Our cabinet was installed in a building extension outside the main shop. In short, no matter what you use for a filter and how well you seal up the cabinet and vacuum system, you're still going to get some dust, particularly if blasting a fine grit such as baking soda. The vacuum will prevent the mushroom cloud though.

I'll stick with blasting the baking soda into my bucket or most times just into the open air outdoors. It's too fine for the blast cabinet and it usually only takes a minute or two to complete whatever blasting I need to do with it, not worth the trouble of sealing up the cabinet, hooking up the vacuum and so on. Air pressure is generally low, between 15 & 30 psi depending on what I'm trying to accomplish. It's just so much simpler to open the door, blast the part outside, and close the door. No need to save the excess baking soda blast, it's cheap, readily available and in the miniscule quantities used, has no discernible impact on the environment. I have a roof overhang outside the shop door which has allowed me to blast outside while it's raining, though with that level of moisture in the air, it's much harder to control, but can be done if necessary.

Paul

[Hauk]

In lack of something proper to post, here is a little follow-up on my blasting cabinet.

I have now built one from a plastic storage box bought at IKEA. I dropped the whole filter thing, since the negative pressure in the box created by the vac lets very little dust escape from the box. I had to drill several holes in the roof of the box to even out the pressure a bit.



If you look closely you can see what really could be called a lazy mans vacconnection. I just glued an old mouthpiece in a hole in the side.





In the picture I hav gloves properly installed, but they gave very little freedom of movement inside the box. So when I did some blasting today I loosened the gloves and just popped my hands (wearing gloves, of course!) into the box and blasted away. It was much more convinient beeing able to remove and insert parts without having to remove the lid of the box.

I have had some trouble getting the eraser to work properly, but it seems that the trick is to keep the blaster at least half full all the time. My blasting medium is a quarz sand from Fohrmann tool in Germany http://www.fohrmann.com/

The blasted parts  got a beautiful matt finish that  was very easy to blacken. I am quite certain it is the ideal surface for paint as well. But a word of caution: thin sheets of brass that is not structurally supported can warp badly.  

Regards, Hauk

[W.P. Rayner]

Looks like a good solution Hauk using readily available materials and given the small amount of abrasive material that the air eraser puts out, certainly all you need for cabinet. Yes the air erasers do work best when they are at least half full.

Paul

[Hauk]

Looks like a good solution Hauk using readily available materials and given the small amount of abrasive material that the air eraser puts out, certainly all you need for cabinet. Yes the air erasers do work best when they are at least half full.

Paul

Did not cost much, and it could possible have been even cheaper if i just dropped the flanged PVC pipe fittings I used for having something to fix the gloves to.
As the box is not 100% transparent, I need to check the parts blasted frequently. Beeing able to remove it for inspiection through the hole is very convinient.

So If you plan somethingsimiliar, go for the most translucent box.

Regards, Hauk

[Gordon Ferguson]

the small amount of abrasive material that the air eraser puts out,

Yea, but it doesn't half go everywhere , as I discovered last week in the spare bedroom ...... well it was cold in the garage!

The dust does matt down a laminate flooring and make anti-slip as well 

[W.P. Rayner]

So If you plan somethingsimiliar, go for the most translucent box.

Regards, Hauk

A good point Hauk. I've had a small commercial bast cabinet for years that I use for any heavier blasting with glass beads. It has a translucent top and it lit inside, but even with that it gets dusty very quickly and I have to pull the part to inspect the process. I have some clear mylar-type sheets that I use to line the inside of the top which prevents the top plastic from getting scratched and marked up. Once the mylar becomes too cloudy to use, I replace it with a new one. Not a perfect system but it works.

Gordon, be thankful you're not blasting with glass beads. Speaking from experience, they coat your floor with a layer of mini-ball bearings, very slippery and they go absolutely everywhere, no matter how carefully I seal the cabinet.

Paul

[greenie]

Try and get the biggest filter you can afford and fit it to the cabinet your making, keep it cleaned regularly too.
The bigger the filter that you can fit, will stop the sides from trying to blow out with the air pressure.
You got to get that pressure out quick, or the dust builds up inside real fast, then you cant see what your doing.

regards  greenie

[Hauk]

Try and get the biggest filter you can afford and fit it to the cabinet your making, keep it cleaned regularly too.
The bigger the filter that you can fit, will stop the sides from trying to blow out with the air pressure.
You got to get that pressure out quick, or the dust builds up inside real fast, then you cant see what your doing.

regards  greenie

But my problem was the opposite!
The vacuum cleaner creates a negative pressure in the box,  the air that the eraser blows into the box is no match for the vac.

[Design-HSB]

Hi Hauk,

I use on my Sandblasbox also a vacuum cleaner.
You have to allow only enough foreign air then it's perfect.
Just once a piece of the lid can be open.

[Lawton Maner]

Guys why not take a lesson from the construction trades where finish sanding of gypsum wallboard is the producer of some of the nastiest dust dust found in the construction of a new house.  Run your exaust into a watertrap upstream of a wet-dry vaccuum.  Very effective as the fine dust is to heavy to escape from the water.  Any of you who are old enough to remember the old style VW Bug should remember it used and oil filled air filter which you cleaned with a solvent (I used Stodard Solvent [ahigh grade paint thinner] when cleaning mine.