Saturday, March 1, 2008

More info on sand blasting

Here's a little more info on sand blasting for those interested in purchasing blasting equipment.

First you will need a air compressor. The small portable air compressors commonly used for air nailers will not work. You will need a unit with a large storage tank. The larger the tank the less the compressor motor will need to run. This will save electricity, extend the life of the compressor motor because it will not need to run as often, and there will be less noise.

Blasters comes in two varieties. Cabinet style that contains the abrasive inside a cabinet and can be set up to reclaim used abrasive. The other style is a hopper style which is a total loss system and is used outdoors on larger pieces such as patio furniture.

Your first inclination is that the cost far out weighs the amount of use it will get. Not really. Your compressor will have numerous uses. Pneumatic tools are great. They have an abundance of power and can be used in damp situations (no electricity). How many times have you wanted to sharpen your lawn mower blades but you haven't the time to remove the blade or blades, sharpen it or them, and then reinstall. If you had a pneumatic hand held grinder you could pull the spark plug wire, lay the lawn mower on it's side, sharpen the blade with your grinder, reattach the plug wire, and start mowing. You will be able to do that really quick if you install a quick disconnect air line outside. Then when you are done mowing your yard, you can blow the grass off the mower deck before you put it in the garage. Then blow the grass clippings off the driveway with this and you'll be inside watching the baseball game before you know it.

Blasting units use a variety of abrasives from course to fine. The type of abrasive used is determined by what you are trying to remove and what you are removing it from. Glass bead and silica sand are two that come to mind. If you blast soft material such as brass you will lose the shiny appearance. Blasting also will give a surface some 'tooth' which will hold paint. If you blast cast iron or cast aluminum vintage light fixtures and then clear coat. They will blend nicely with the new brushed nickle and stainless finishes.

Blasting not only removes paint but also rust and in the case of car parts baked on grease and oil. If you are using a unit that reclaims the abrasive do not blast oily greasy parts as it will contaminate your abrasive. Also all abrasives wear out. You'll notice after a period of time that it takes longer to remove paint etc. This is because the abrasive has pulverized into dust causing it to lose it's sharp edges. Think about what sand at the beach looks like upon close inspection. Each grain has multiple sharp edges. That's why after a day at the beach your feet are smoother. We generally use play sand in our hopper style blaster. The reason being that it is inexpensive (cheap) and we can just sweep it into the lawn when we clean up. Most people use glass bead in the cabinet style units. Also remember when using the hopper variety to wear a protective hood to protect eyes and keep abrasive substance out of your hair.

When setting up your compressor take into consideration noise. Some people locate their compressors in the garage and then run the line to their basement work shop. The most convenient way to plumb your compressed air is to run your piping completely around your workspace. Every 10 feet or so place a quick disconnect. You can even run a line overhead with a quick disconnect over work benches. If you can plumb for water then plumbing for air will be a breeze. The good part is if you have a leak after won't get wet. Also if you run a line outside you can easily air your tires up or inflate the inflatable kiddie pool.

Tonight I sand blasted a cast iron mailbox that I intend to place by the kitchen door. It is made by Griswold of Erie, Pa.
After about 30 minutes of blasting the mail box looked like this.

I used a brass brush and razor knife to loosen some stubborn areas and I will probably blast it one more time before I prime it. I'll wait and paint this when I paint the light fixtures.

I was asked if I was using an online source for information on how to blast. No, I'm not. Fabricating is part of my job as a journeyman. At a later date I'll talk about the week long metal fabricating class I attended. The week before I took the class, Jeff Gordon's fabricating crew were there perfecting their technique.

Tony is starting 25th tomorrow in the race in Las Vegas. Good luck and goooooo Smoke.