Instructables

Homemade Shot/Grit Blasting Cabinet

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Picture of Homemade Shot/Grit Blasting Cabinet
A cabinet for shotblasting small to medium sized components without the mess of open blasting, built entirely from stuff I had around the house and workshop.
 
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Step 1: Introduction

I recently bought a small compressor with tools for my father's car workshop. I also got a shotblasting gun that that uses the venturi effect to draw grit from a bag and blasts it out with the aid of the compressed air.

While effective at removing rust and old paint, it is incredibly messy. I resorted to wearing a motorcycle helmet, balaclava, overalls, gloves and boot and would still find it the grit in my ears and inside my clothes after a blasting session. Also it went all over the workshop. With blasting cabinets costing more than the compressor did, I decided to build my own.

Step 2: Tools and supplies

You will need:

a large plastic container,
I used a recycling bin which is now defunct as the council have just switched to wheelie bins.

some clear plastic,
perspex (plexiglass) will do, i actually used polystyrene as it was what i had lying around

some strong adhesive,
no more nails or similar is perfect

some wire mesh,
mine was from the grill of a truck, and old grill tray would work even better

2 small blocks of wood and some screws,
these are to hold the tray off the floor, virtually anything could be used

Tools:
jigsaw or fret saw
tenon saw
hacksaw
drill (hand or power) with bit big enough to get your jigsaw or fretsaw blade in
files for finishing
screwdriver
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Phil B5 years ago
Will the plastic window need to be replaced after a while because the sand or shot roughed up the inside surface?
kington99 (author)  Phil B5 years ago
Not sure yet, professional versions use polycarbonate, i suspect for this exact reason. With the relatively low power blasting I'm doing the window should have a good life, and periodical polishing with a good paint cutter (have experience of doing this from perspex windscreen in car) should remove the damage and thus prolong the life.
Save yourself the time and just go find some clear plastic film at an art, craft, or hobby store. I just did a google search for it and found 20 inch by 50 foot roll of .003" thick optically clear film for $15... Trust me: no matter what media you use, and no matter how careful you are, your screen is going to be wrecked in a hurry without a protective film. When the plastic film gets wrecked just tear it off and tape a new one on. As for the leakage, have you considered making the glove a permanent part of the cabinet? Just cut it enough to flare it out and tape it to the outside of the cabinet. Would help to have felt lined glove so your hands slide in and out easily even when they're sweaty. If you're using a dusty media (glass bead for example) you could improvise a dust collection system with a vacuum. You could even do it in reverse where you force clean air in (blow port on shop-vac) and just have an exhaust routed to a filter bag.
}{itch Linksep5 years ago
A slightly cheaper way could just be to use some cling film, my dad uses it on the perspex window of his cabinet, you have to stretch it quite tightly to stop wrinkles, but it seems to work fine. @kington99 cool instructable :)
Jo0Lz }{itch4 months ago
thats a great idea....I.'ll try cling film on the window of my blast cabinet ?
This is a little off the original topic but it sounds like this stuff would work great on motorcycle helmet face shields.
What you do in this case for yes, the plastic will get pitted..but you can go to any major art store and buy clear graffix acetate sheets they sell to protect artwork and tape them over the window..when it gets pitted ,simply peel the sheet off and put another one on.This keeps you from having to replace the actual window itself.It seems I have gotten into a site that is overseas from me, but I like the forum and would like to share my knowledge.Here is A link to what I am talking about.These stores may not be available in your area, but the products will be at your local stores.Any art store has these.Available in rolls as well
http://www.dickblick.com/products/grafix-clear-acetate-sheets/
Hoopajoo Phil B5 years ago
I use a professional cabinet to glass-bead the bushcrafting knives I make. to keep the lexan window from getting marred, I place a clear film over the inside of the lexan and replace it when it gets difficult to see inside. I guess you could use a couple of layers of clear packing tape the same way, just be careful not to point the blaster up.
If you a filling a sealed plastic container with air it will very quickly over fill and start to bulge and potentially 'explode' showering the user and anyone nearby with grit! Very dangerous. You need to have some form of valve to let the air out but keep the grit in. On my version of this I have fitted a sponge filter which lets air out but keeps grit in.
kington99 (author)  Mindmapper11 year ago
Yeah, it's not sealed, it has a four inch hole in the front for my hand as you can plainly see, also the lid is not airtight and more or less just rests in place, should you somehow manage to seal it entirely the disaster that would result is that the lid would lift very slightly, releasing the pressure.
Kevanf13 years ago
How about an improvement for this? Fix a large plastic funnel in the base of the box. The blasting medium could fall into the funnel and this in turn be collected in a pot. Obviously you'd need to have the cabinet raised up but this would eliminate the problem of the grit layer being too shallow to be reused straight out of the box.

Good 'ible', well done.

Kevan
Basta4 years ago
This looks great, way simpler than I thought possible. One thing I was wondering--what sandpaper grit do you finish your work to before blasting? I make knives and I'd like to try doing this in preparation for parkerizing. I just hate mirror-finishing metal.
kington99 (author)  Basta4 years ago
I don't, I use it for cleaning heavily dirty/corroded components off cars, I'm afraid i can't help you with your question.
Basta kington994 years ago
That's okay, thanks for responding. I still might do this when I get a chance.
scale215 years ago
so how does the top not blow off or the sides buldge when you apply the air? is there a vent somewhere? I have a project im doing where i need to blast a few things but cant figure out how to make the cabinet.
kington99 (author)  scale215 years ago
the lid is by no means airtight, nor is the fit around the glove, and the airflow rate I am using is not high, so it can easily leak away fast enough. A filtered vent might be a good idea if you're using a much larger compressor.
id like to build somthing like this for temporary blasting of small parts. I need to run about 90psi for it to be effective. I wonder how you could vent this properly. Ive tried just using the gun in the open air and what a mess!!
Here is a link that you can make a water filter system that works similar to A bong..You can hook up a common shop vac to it without the grit frying the motor..I found this today and going to modify mine tommorow with this system..I been running a shop vac with the filter bags they sell for them, but thats 10.00 for 3 of them..with this system, I won't have to buy the bags no more.
http://www.chevytalk.org/fusionbb/showtopic.php?tid/197304/pid/1508054/
Open the page and scroll down a little ..it is quite easy and cheap to do
kington99 (author)  scale215 years ago
I am running similar pressure and about 8 cfm, to vent it cut a hole in the tub and cover it with a thick piece of foam, such as car air filter material. This will let the air out and keep the grit in.
My dad has a sandblaster that he borrowed off a mate and he just uses a vairable speed vacuum cleaner to filter out the dust and keep it from exploding
tmjones5 years ago
wondering what you use for grit, standard sand or metal?
Depending on what you are blasting..for metal parts that you do not want to change the structure of or pit it, I suggest walnut shell for it will not damage the metal, you can even blast internal engine parts such as pistons, cranks etcetera..Heres another clue..Instead of paying high prices for it, any major pet store that sells pet supplies sell ground walnut shell for lizard bedding.The grit is too large for smaller spot blasters, but A food processor will grind it on down further for you.
kington99 (author)  tmjones5 years ago
I'm using iron sil, which is sold as a fine blasting powder on ebay.
This is a cool idea. I have a rifle and a few other small pieces to do. I have no idea what kind of compressor I need. Actually, there is not a thorough A-Z list of what one needs to do to make a decent setup. Can anyone help out? I don't care about how long it would take, just a basic setup to remove paint from steel is all I need.
May I add be sure to order additional ceramic tips for they average about 6 hours use per tip..this unit uses harbour freight number 38479 tips..7.99 for 5 of them I think..the shipping rates are on here, so might as well order tips with it and only cost an additional 1.00 other than paying 7.99 later on for shipping
Coolio, my little set up cost me 29.99 total delivered (us dollars) from harbour freight..They have a cheap starter set up...this includes the hopper,the hose, and the gun to.This spot blaster only requires a 1 horsepower compressor..go to harbourfreight.com and in the search box type in "sandblaster" and it will take you to the page..the actual product number is 37025-0VGA and if this site allows links here is the link to the actual page.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=37025
I am just A beginner and this is a great cheap learning blaster..make sure to take note(it dont tell you here but thier tech support told me) that you don';t use too large a grit..this unit takes from 60 to 300 grit abrasive..the larger the number the smaller the grit of course..for low dust I suggest glass beads or walnut shell..I do not know where you are located, but this will give you an idea there is alot of cheap beginner tools out there..make sure to take note of the cfm's before you purchase one and that your compressor will take it..This one is one of the lowest cfm's they have
kington99 (author)  coolionoolio5 years ago
you need a compressor, prefferably atleast 1.5 hp and 25 litre collector, an air hose, a shot blast gun and a bucket of blasting grit. If it's only a few small bits it would be cheaper, quicker and give a better finish to pay to have it done rather than buying alll the kit.
mrruger5 years ago
great idea. i plan to make one soon. just wondering, how do you vent the air pressure that builds up?
The little shop vacs that are 12 volt dc would be great for this small blaster
pcbeachrat4 years ago
I just joined the site and just now getting into blasting. I read many articles and just made my own blaster from an old refridgerator with the freezer on top. I turned it upside down so the freezer was actually A place to put A container to recycle your media.I bore A hole between the freezer and fridge and put A funnel in it so the media would drop into it.I attached a ligght up top with a homemade shield to protect the socket, then for dust problem got A pvc coupler that was a compression fitting in the top that a shop vac tube fits right into it, tighten it up and snug as a rug..They sell shop vac filters that are actually a fine meshed bag like a vacuam cleaners(9.95 for 3) at walmart..This keeps the grit from getting in the shop vac motor and frying it..Nice to join the site.Later I will add links to the pictures and further detail.But..does anyone know A good way to make thier own blasting media from pecan shells? Would A common food processor work? We don't have many walnuts here, but tons of pecans and I can get the shells by the ton free. As I say later I will add pictures of mine in detail for anyone wanting A larger blaster. It works well, but I learned alot, a few mistakes, but now I have them tweaked out..Nice to be here..
Beest9215 years ago
Beautiful! A work of art! I've been in the auto body/restoration business for over 30 years and countless times I've needed something for blasting smaller parts, but couldn't come up with something that I was happy with. I will build one TODAY! Great job! Thank you!
Could you have the source of your grit be the bottom of the container so it continuously uses it? Then just change that periodically. Would it get too contaminated that way? Obviously this idea would work better with a different kind of container.
kington99 (author)  X01X01X01X015 years ago
Hi, if you read through previous comments that idea was explored in depth. basic answer is in this case no, the layer would be too shallow, you'd have to move the pickup hose around all the time. In a taller box, yes good idea.
djpaone5 years ago
I like it. You could use a leg from an old pair of jeans and duct tape it to a glove and the box to keep dust low.
mrruger5 years ago
great idea. going to make one soon. just wondering, how do you vent the the air pressure that builds up?
kington99 (author)  mrruger5 years ago
Ah yes, the seal around your arm is sufficiently poor that the air pressure can bleed out. If you had a built in glove then you'd need a vent somewhere else the lid would blow off.
i see. many thanks.
chalky5 years ago
Great idea mate! i too have bought a compressor with 'free' grit blast gun and using it is a nightmare,its like been stuck in a sand storm lol as soon as i find/source/beg/borrow:) a suitable box i will be knocking one of these up for sure! 10/10 from me on this one
doyle 375 years ago
if any one is thinking of making one, make the window easily removable as even glass in a small low powered grit blaster gets blaseded indirectly and fogs up, all that said, nice build well done
tornadoboy5 years ago
Great project! You don't want to breath sand either, if you get too much of it in your lungs over a period of time it can be fatal.
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