Sand Blasting
Sand Blasting
Lots of times we run across motorcycle parts that have been, shallwe say neglected? Parts that are badly corroded. To clean theseparts we need more then than a tooth brush and some solvent. Weneed to really blast those parts clean.
A Sand Blaster takes the blasting media of your choice, blows itthrough a gun shaped nozzle and onto the part you want cleaned.This gun uses the venturi principle and compressed air to suck theblast media, through a tube, up into the gun and out the nozzle. Atrigger on the gun controls the blast of air.
While there are lots of different grits and sizes and combinationsof media it really boils down to this. There are basically, threetypes of blasting media.
- Walnut Shell
- Glass Beads
- Sand
 Walnut Shell at 60x |
 Glass Beads at 60x |
 Sand at 60x |
If you have a part that is not toobadly corroded or a part off a bike you are restoring that must notbe damaged, walnut is a good media to clean up that part. Walnutwill clean the part without removing any metal or changing thesurface of the part. Walnut does a good job if the part is justdirty. I had a piece of duct tape separating the blasted andunblasted surfaces. Notice that the part is just cleaned and thesurface of the metal is not changed. There is not much differencebetween the cleaned and uncleaned surfaces except that the surfaceis clean.
The next grade up is glassbeads. Glass beads are, well, beads of glass! They are round andwill not take off much if any metal. They do sort of harden thesurface of the metal. This makes glass beads especially good forcleaning internal engine parts. Not only do you clean the part butthe bombardment of the metal with the glass beads actually hardensthe surface of the metal. Glass beads are easier to clean off theparts too. Notice the surface looks like you hit it with a millionstrokes from the words smallest ball-peen hammer.
The final step is sand. Man, will it cleanthe rust and corrosion off a part! Sand will chew a hole rightthrough a metal part if you hold the blaster gun on the part longenough. In fact, if you mask off a small circle on a piece of glasswith duct tape, you can drill a hole right through it with sand.Notice the part looks like it has been worked over withsandpaper.
Sand tends to get into every crevice and hole and stay there nomatter much you clean. This can be a problem. If a piece of walnutor a bead of glass gets into your engine things are not so bad.Sand is a different matter. It can really grind things up, sochoose your blasting media carefully!
Once you decide on what typeof blasting media to use you will need to decide on exactly how youwant to blast the part. This can be simple or very complex! Theeasiest way is simply to buy a blasting cabinet. They come in allkinds of sizes and shapes depending on how big the objects you wantto blast are. Prices start at about $100 and go up to thousands ofdollars. You can make a cabinet too.
You don't have to have a cabinet but it sure helps if you do haveone. You can just buy a portable gun and media hopper kit and haveat it! This works but has two distinct disadvantages. One, it'swasteful and two it's down right messy. The blast media isreusable. Yes, it does wear out with use. However, unless you areworking on a special project that needs a very uniform finish, youcan reuse it many times. As to messy. This stuff goes everywhere.If it is contained in a blasting cabinet you will not be getting itin your mouth, down your back, in your ears, well, you get thepicture.
If you have a part that is just too big for a Blast Cabinet (like amotorcycle frame) you can use a portable gun like the one above andthen build a big tent out of 1×2 or 2×4 wood, plastic tarps andduct tape. Then blast away! When the media hopper is empty simplysweep up the spent media on the floor and put it back into thehopper. Build the tent big enough and you could blast a carbody!
A word on safety here. If you use a blast tent or just blast out inthe open you need a good respirator and good eye protection. Thinkabout it. The blast media does degrade as you use it. Breathingglass dust or sand dust will not do your lungs or your eyes anygood!
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