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PeteF
06-17-2010, 08:29 PM
I have a small sandblasting cabinet using garnet as the media. I notice in my cabinet there is a lot of "dust" within the media. When I initially started using the cabinet it had a filter on the exhaust port which basically stopped this dust from being extracted to the vacuum system. I've since removed the filter and hope it will reduce the build up. I appreciate with time the garnet wears out as it breaks down to finer and finer particles, but I was wondering if it was possible to sieve the mediat? The very fine dust makes blasting difficult to see at times. It probably also consists of fine paint etc etc particles that have been blasted off parts so it's probably not a good idea to get a lung full of the stuff if I do try to sieve it!

Simply replacing the garnet is certainly an option and not especially expensive but seems a waste as the vast majority of the media is perfectly ok. Just wondering what others do?

Pete

Forrest Addy
06-17-2010, 09:13 PM
You can filter your media and pour it from a sieve through a cross draft from a fan so the drifted media falls according to size into a series of selective capture bins. The fines are carried further by the airstream and the heave whole media falls closer to the seive. Probably tricky to conceive from my description but it can be cobbled up with simple equipment like a couple ladders to carry planks, plastic tarps, some wood frame screens, a breeze box fan, and some cheap dishpans. Play with it a little, reduce the scale of the components, and I would imagine a clever improvisor could fit it within a couple cubic feet. Once that's done it's a simple matter when servicing the blast booth to cycle the in-use media through your home brew classifier. This way you trash the dust and spent media and save the stuff that's still good, adding only the media necessary to replenish. Saves $$.

If you're made of money there's a gadget called a "classifier" that automatically processes media to remove dust, damaged media, rust and paint flakes etc collecting this debris in a bin so that nothing but clean sharp media us available to the nozzle suction. You find these items in higher end blast booths that use a suction type gun nozzle.

PeteF
06-17-2010, 10:33 PM
Ok thanks Forrest, no I know exactly what you mean, that's a good idea. I probably only need to worry about go/no go type of sorting if you like, so I could probably just arrange a fan blowing into a cardboard "funnel" on its side, with the vacuum at the base of the funnel taking the fine dust off to the collection canister. If I slowly drop the media in the gap between the 2, the fine dust should be carried off. The vacuum has a hepa final filter which I'm grateful for as I suspect some of these old paints would be chock-a-block full of lead!

Hmm, come to think of it, I was after a chaff separator for my coffee roaster so that could work on the same principle as there's no contact with anything, the media/coffee simply drops from one container to another. Excellent!

Farbmeister
06-18-2010, 07:02 AM
You need a better vacuum. A classifier is gonna be way out of your range.

Why go through the 'blowing step' when you can eliminate most of the dust when its created (in the cabinet).

Any good shopvac will evacuate the dust and its filter will trap it. Most GOOD (aka $100+) shop vac will include a HEPA filter.

My Craftsman shop vac (about 5 years old.. still on the original filter) can clean the dust from my cabinet (4x4x4) for about an hour before I have to remove the filter and bang off the dust into a can (outside).. takes 5 minutes. My pressure pot usually only lasts 20 minutes.

The key is to get a good flow of air accross the box.. either by drilling several small holes or like mine, its leaks around the front door... but the shop vac pulls enough to create a low pressure in the box and keeps all the grit in the box.

This way your cut your sifting WAY down and dust is eliminated immediately.

I've been thinking about the 2hp dust collector that HF sells... its most likely for wood... but my garage would allow me to simply blow the stuff outside (or filter with water) when my trusty Craftsman finally gives up the ghost.

garagemark
06-18-2010, 08:27 AM
The 2 HP HF dust collector will have to be throttled to work with a BB cabinet. It has way too much suck and will carry more than just the fines away. You would be better off with a much smaller dust collector, or shop vac. Add any size bag filter you wish, or use a canister filter, which is designed to be easily cleaned from the outside.

I upgraded from the vac to the six (or nine, I can't remember) bag filter from TIP when I bought my cabinet (the old TIP). It works very well, but it does not suck hard... Just hard enough to carry away fine dust- not media. I did however have to cut a port in the oposite end of the cabinet for makeup air.

JoeLee
06-18-2010, 08:28 AM
Sand and that black stuff, Black Beauty are quick breakdown media and tend to be quite dusty. Try glass beads, they leave a softer finish and no dust. Your window will never cloud up with dust. Also if you have a plastic window on your cabinet replace it with laminated safety or tempered glass, it will last almost for ever. My cabinet originally had a plastic window and I was changing it almost every month.

JL....................

bborr01
06-18-2010, 10:59 AM
I had the same problem with my cabinet blaster.

I used a 20 inch box fan and a couple 5 gallon buckets.

Poured a light stream of media from one bucket to the other in front of the fan.

The dust blows away and the good media goes in the bucket.

I have since hooked up my shop vac to the cabinet and that seems to be removing most of the dust.

One word of caution though as previously mentioned.

You will need additional inlets for the air to enter the cabinet or something will have to give.

In my case, the glass window cracked right in the middle and sucked into the cabinet. Scared the crap out of me for a second.:eek:

Brian

Black_Moons
06-18-2010, 01:15 PM
Get two large (long?) screens, a course and a fine
set on say, a 15 degree angle, with a small lip on each side (2x4 frame?)
Fine one first, course one second, bins or collectors under each. overlap the fine overtop the course at the seam

Apply media and shake the screen (a motor with an offset weight on the shaft could make it automatic, or whatever..)

Everything that falls through the fine screen is rejected as dust/debrie, everything that falls through the course screen is 'good media' and anything left over is large debrie