Media Blasting Part II - Setting up a Sandblast Cabinet

This article will talk about setting up a media blasting cabinet to be as efficient as possible so that you can easily prepare your parts for powder coating. I explained the different types of media blasting methods such as pressure pot, siphon blasting, sandblasting cabinets, blasting outdoors, and dedicated media blasting rooms in the previous article: Media Blasting.

For most powder coaters, a media blasting cabinet will be the most ideal way to prepare your parts for powder coating.  They are available in a range of sizes that will suit small DIY projects up to very large projects.  Media blasting cabinets keep all of your blasting media contained in a sealed environment and which allows you to get the most use out of your media and also keep your area clean. Here is an example of a cheap media blasting cabinet for a small DIY powder coating setup:

Powdercoatguide.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.  

Cheap sandblasting cabinets are great for DIY coaters because the internal dimensions pretty closely match the size of a household oven. As long as you don't get to claustrophobic, you don't necessarily need a gigantic blasting cabinet.  An exception to this is that while most wheels will fit into the cabinet like the one mentioned above, if you want to turn the wheel over, it has to come out of the cabinet, be flipped around, and go back in. This is the point where you may want to spend the money on a larger, higher quality blast cabinet or hire-out your blasting.  Unless you buy a larger cabinet that comes with great lighting, built-in dust collection, and is perfectly air tight out of the box, then you will need to do some modifications to your cabinet to make it more efficient.



Optimizing a Cheap Sand Blasting Cabinet

Caulk the Cabinet's Seams

First, the cabinet I mentioned above is about the cheapest floor-standing cabinet available that closely matches the dimensions of a household oven. So of course, it is going to need a little tweaking. The first thing I did after assembly was to caulk all of the seams of the cabinet to make sure no sandblasting dust can escape the cabinet.  If there is even a minor leak in the cabinet, you will notice that every surface of the garage will be covered with dust after awhile. I highly recommend Silicone free caulk to seal up all of the inside seams and through bolts in your cabinet.  This should be done before you have added any blasting media to the cabinet, otherwise, you must thoroughly clean the cabinet for the caulk to seal correctly.

Upgrade the Sandblasting Gun in the Cabinet

This is not 100% necessary but if you want an efficient sandblasting cabinet, a better sandblasting gun can make a world of difference.  Skat Blast sandblasting guns are a great upgrade as they are more powerful, faster, and more comfortable than the guns that come with a cheap cabinet.

There are different versions of the gun and nozzles available for different air compressors:

Air Compressor Output      Gun                            Nozzle
4-9 CFM                                 S-35 Small                 Small Ceramic
10-15 CFM                             S-35 Medium             Medium Ceramic / Medium Carbide
20-25 CFM                             C-35-S Large              Large Ceramic   
25+ CFM                                High-Volume Gun      High-Volume Head




The next step is protecting the window.
 
Your blast cabinet comes with a tempered glass window for safety reasons. If you do nothing to protect it, the window will slowly be etched by your media bouncing back and hitting the glass. This can happen to the point of not being able to see through the window at all.

Peel-off window films protect the sandblasting cabinet window. These are just like the little plastic sheets you put on the touchscreen of your cell phone. They are meant to be applied to the window and they take the beating instead of the glass. The life you get on them depends on how close you blast to your window and what PSI your blasting at. Blasting should be done as far away from the window as possible and at a 45° angle so that the media deflects off to the side of the cabinet instead of right back at it.  Once the film becomes etched, just peel it off, clean the glass, and apply a new film. 




Another option is going down to Lowe's or Home Depot and having a piece of glass cut the same exact dimensions of your window. They charge about $10 for glass that size and they will cut it for free. (UPDATE: Some Lowe's and Home Depot have stopped cutting glass to custom sizes. Please call ahead first.) Then just take that piece of glass and place it on the inside of the tempered glass that came in your cabinet. The cut piece of glass will last longer than the sticky film sheets mentioned above but you do have to disassemble your window shroud every time you want to replace the protector glass. Also put a piece of tape around the border of the two pieces of glass to seal them together. Otherwise media will manage to get lodged in there and there is no way to get it out without disassembling the whole window frame.




Lighting your Cabinet:

Most media blasting cabinets come with some sort of overhead light.  If you are using a bench top blast cabinet or if you would like some extra light, a very cheap light that works well is a fish tank hood light placed on the top portion of the blast cabinet window. It is what I use on my cabinet, and it provides all of the light I need. Because the light is outside the cabinet, it is protected from dust and from being etched by the media. If you use any internal cabinet lighting, the dust can build up on the light until the point that no light is visible. However, in blast cabinet, the more lighting, the better. Puck lights or LED light strips are a great way to add more light.  Just keep in mind, that without some kind of protection, they will eventually become etched by the blasting media and lose their ability to light up the cabinet.  So either go cheap with the lights or use some kind of glass or plexiglass shielding. Even more important is to protect any of the lights wiring running inside of the cabinet.  It wouldn't take long for for the blasting media to wear away at the wire insulation which could turn your entire media blasting cabinet into a shock hazard.

Dust Collection:
 

Whatever media you use are using to blast with will eventually break down into fine dust. It will float around inside your cabinet reducing visibility to the point that you cannot see a thing. It will also leak out of any openings in the cabinet and completely coat every thing in the room. This is where a Dust Collector comes in to play. These are specialized vacuum systems that you hook up to your cabinet. They clean all of the dust out of the air in your blasting cabinet. Media blasting cabinet dust collectors can be a little expensive for most hobbyists, costing more than the cabinet usually, so it is common to build your own using some DIY methods.





DIY Dust Collection:

I have used an improvised dust collector made from an old vacuum cleaner and a thein baffle. I eventually switched to a shop-vac which is more powerful and quieter but it takes up more space.  If you have neither, go with the shop vac. I personally believe Rigid shop-vacs are superior to the other brands when spending less than $200.  If you don't have any floor space available, wall-mount shop vacs are available that will keep your sandblasting cabinet area tidy, however, most of them come with a 1 7/8" diameter hose instead of a 2 1/2" hose of a standard shop vac.

There are two issues with using a vacuum or a shop vac. The first one is that they are much louder than an actual media blasting cabinet dust collection system. If I am going to be blasting for longer than a couple of minutes, I will wear ear plugs or headphones to avoid listening to the constant drone of the vacuum.  The other issue is that shop-vac and vacuum filters are not designed to catch small blasting particles. The dust particles produced from blasting are smaller than the filter can catch allowing them to travel right through it and into the motor. These particles will quickly wear down the motor. The particles that don't flow right through the filter will quickly clog the filter which leads to cleaning the filter after every half hour of blasting which gets very tedious.

A way to overcome the constantly cleaning the filter is to pre-filter the blast media before it reaches the vacuum.  The type of pre-filter commonly used is called either a thein baffle or water bong. It can be made with a 5 gallon bucket, two vacuum hoses, and some cheap plumbing fittings.


The idea is that the as the media is sucked through the first hose, it is pointed directly downwards toward the water where it will get trapped, but the air can still pass up to the hose connected to the vacuum. It works surprisingly well and extends my filter cleaning periods from 30 minutes to a week. But now cleaning the filter means scraping out wet sludge out of the bottom of the bucket, filling back up with water and putting back into use.

Quick instructions on what how I made this. I save vacuum parts like the hoses and tubes because I have found several times when they served to be useful.

MATERIALS NEEDED:

• 2 vacuum hoses(a vacuum or shop vac should have one already)
• 1 tube that fits inside the first hose(I used the extension tool that comes with vacuums, cut to length, pvc pipe would work also.
• 1 something to angle the 2nd tube towards the wall of the bucket(I used another vacuum tool here, the little brush attachment that is for cleaning upholstery, I just cut off all the bristles)
• 5 gallon bucket with tight fitting lid
• caulk

STEPS:

1. Cut 2 holes in the lid of a 5 gallon bucket. I just traced the outside diameter of each vacuum hose onto the bucket lid and cut it the holes using a Dremel. If you have hole saws the same size, great, use those.
2. Insert hose end into bucket lid, I cut mine out so it would fit pretty tight. I then sealed both sides of the lid with caulk. Do the same with the other hose end.
3. Attach 1st hose to a hole in the cabinet. My cabinet already had a hole in it for for this purpose and it also had a block off plate since the cabinet didn't come with a dust collector. I originally cut a hole in the block-off plate and sealed the other end of the hose to the plate. This meant that the bucket lid was permanently attached to the cabinet though so I later changed this to a removable design.
4. Wait for caulk to dry so you can handle the lid.
5. Insert extension tube into 1st hose and cut it off about 4 inches from the bottom of the bucket.
6. Insert angle vacuum attachment onto other hose
7. Fill bucket with water just below the tube(if the tube is going directly into the water, it can cause a vacuum so strong that it will crush the bucket)
8. Hook up 2nd vacuum hose to vacuum.
9. Your blast cabinet will need some type of breather to allow air in, otherwise the negative pressure tends to suck the gloves right off of the cabinet. My cabinet had a 2nd hole in it for whatever reason along with a block off plate. I just removed the plate and taped a Scotchbrite pad to the open port to prevent media from flying out.
10. Optional: If you use a shop vac, you can skip this since a shop vac is already pretty compact. A regular vacuum is pretty bulky in my garage. I took all the unused stuff off the vacuum: the handle, the entire bottom section with the wheels and brushes and other random pieces. Now it fits with the bucket underneath my cabinet near the back so it takes up no room.

A Better Alternative to DIY Blasting Cabinet Dust Collection:

A much less labor intensive alternative to the thein baffle mentioned before is a Dust Deputy and it's conical design will work better than the plumbing fittings used above.  These are very commonly used in home shops for dust filtration. They are designed to hookup to a standard shop-vac and catch all of the small dust before it reaches the vacuum.  In other words, they are designed for exactly this purpose.  The Dust Deputy can be ordered here but you will need your own bucket and vacuum hose.  You will also need to modify the bucket lid to mount the dust deputy.  If you want a ready-to-go setup, they also offer this kit that comes with the bucket and extra hose.

For conveniences sake, I attached a power strip to the sandblasting cabinet to plug the vacuum and lighting into.  With the switch on the power strip, I can turn everything on and off as easily as if it were built in.



With these adjustments and modification, even a cheap cabinet like the one I use can work great. However, if you want a very high quality cabinet set-up out of the box, complete with lighting and a dust collection system, this TP Tools Blast Cabinet cannot be beat.  It is literally the best deal I have seen for a complete cabinet of this size with all of the high-end features. 

Media Blasting Outside or in a Blast Room

Lets say you are a little bit more serious and have a large powder coating oven big enough to do subframes, axles housings, etc. Parts like this would need a huge blast cabinet so that is the point where you may want to take your blasting outside or set up a dedicated media blasting room.

To do blasting outside, you need to protect all of your skin, your eyes, and your lungs. A sandblasting hood will help keep your head protected, and I never blast outside the cabinet without a respirator. Make sure you avoid using sand whether blasting in a cabinet or outside. Blasting with sand is dangerous for your lungs and there are much safer alternatives. 
and long pants will be fine to cover up your skin. For your face and eyes,

If you plan on media blasting at more than a hobbyist level, such as everyday at work, you may want to look into a supplied air breathing system to supply clean air to a sand blasting helmet. With this, there is a small compressor that supplies filter air that is safe for human consumption. You place the compressor in an area that can take in clean fresh air and it pumps the air to your mask for you to breathe. This is also the only way to ensure you are protecting your lungs when painting with two part automotive paints.

Now that you are suited up and ready to blast safely, I recommend setting up your blasting area on a large tarp. This serves as a clean place for your used media to land while your blasting. Once your bucket or pressure pot of media is empty, you can sweep it up and pour it back in to get more use out of it. Just make sure you filter the media. I use a window screen folded over itself a couple times.

If you are in a professional environment, or just have a really big garage, you can setup a dedicated blasting room for large parts. This works out basically the same as blasting outside, except your media is contained in the room.

That sums it up for setting up your media blaster / sand blaster. It is really a great tool to have and once you have one, you will wonder why you didn't have one all your life.