Sand & Bead Blasting


Capt. Mike

Moderator
Cabinet bead blaster

This is almost self-explanatory. Don't know how I ever got along with out one. I had a sandblaster and rarely used it because it was a first class pain in the behind. Set-up, then protect your face and breathing. Sand flying everywhere to be cleaned up later. By the time I was finished, I'm not sure who was blasted more. Then one still had to clean sand out of clothes, hair and ears. Phooey!

Along come the bead blaster. In many sizes and abilities, the are basically a sand-blaster in a box. There's a door, usually at one end, and a big picture window on the top. There are two glove-like inserts through the front face and there is a gun inside. The air supply may have a foot pedal or be a trigger on the gun. The work rests on a grate so the sand falls through. The reservoir is tapered so the used sand falls to the bottom and the pick-up tube. They typically have 1 or 2 work lights inside. Blast away then open the door and remove your rust-free item with no mess and no clean-up. Mine is a TiP or TP Tools brand; see their topic in this forum.

Most have a vacuum arrangement high in the cabinet to take away dust without sucking out the media (sand). Since the media dust is very fine but still harshly abrasive, dedicated vacuums with special filters are preferred. Cheaper units hook to a shop vac, but expect quick filter clogging. Premium units will have a pre-filter trap for larger media and I've added an exhaust filter for any fine dust that passed through the main as I found a layer of dust accumulating around the unit.

This is a little general. I've used the term sand for media too liberally. There are a dozen or so different types. Very fine glass bead, and even plastic are used for fine polishing and cleaning, such as aluminum cases. Crushed walnut shell is often used to polish brass. There are several 'trade-name' ones that are either versions of glass bead or man-made materials. "Skat-magic" (a TiP brand course glass bead") is a good general purpose cleaner and mild de-rusting. Aluminum oxides are heavier duty. "Black Magic" is a commercial heavy-duty scaling media. You can, of course, use dry sand in a couple of grades.

Bead blaster cabinets come with a quick-change feature. Since the bottom is a tapered collection bin, they have a trap-door so the media can be dumped. Most users will have 2-4 favorite medias and dump it into a large Rubermaid tub with lid. Then one adds the new media through the loading door. This provides an opportunity to screen it. Larger flakes of rust and paint can clog the pick-up. The beauty of a cabinet is you usually only need 25 to 50 lb. of media since it's all recovered.

Media does wear out. The 'blasting' effect is the sharp edges of the media. As it's used, the impact on the object gradually rounds out these sharp edges and the media loses effectiveness. But it will last a long time -- often years. And changing is a matter of dumping the old and then filling with new.

Bead blasters require a large air supply (big compressor) but one can pick various nozzle sizes to match from about a 2HP up. They require absolutely dry air so a regulator and filter AT the cabinet are a must. This also means the compressor has to be serviced and drained frequently (see "Air Compressor" topic). Since blasting uses the compressor heavily, it can get very hot. I suggest you put a high-speed fan across the compressor cylinders to supplement the compressor's, if equipped.

TiP (TP Tools) is one of the largest suppliers to shops and hobbiests, however their on-line catalog does not contain their full line of products. They even sell do-it-yourself kits where you get the working guts and supply plywood to build the box. Ready-made uses sheet-metal for the box (preferred).

They do eat up floor space. The little bench-top units probably aren't worth the trouble. Like compressors, go as big as you can possible afford & fit -- you'll grow into it. Pretty soon you'll find yourself blasting and repainting much of the stuff that comes off your Westy during service & repairs. Before you know it, you Westy isn't so grungy after all.
 

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Capt. Mike

Moderator
Siphon type sand blasters.

Long before I had my bead blast cabinet, I had a siphon style blaster. Mine is a Montgomery Ward brand, plastic container, top screen and bottom draw. It uses a suction gun -- compressed air to the gun creates a vacuum, pulling media from the container up a separate hose. The mix then blasts the object.

Siphon style come in various levels of quality and configuration. Some use plastic containers. There are even super-cheap units that stick a siphon tube down into a user supplied bucket. The better ones have a metal container, sit on legs to help funnel the media, and have guns of higher quality.

These blasters are surrisingly effective. The blast is dictated by the air supply power and if the gun can siphon sufficient sand to feed the need. Obviously a little compressor won't give you the quick blast of a big unit and they lack the ability to adjust media flow.

I see plastic ones in the $50-$75 range; Northern was selling a metal one with legs for $40 last time I looked while I saw what appeared to be the same unit for $110 at a "sand blaster" site. Read the specs -- if you can supply 90 psi air at 7-8 SCFM you can get a serviceable job from these blasters. You will have to adjust nozzle size to air supply.

These blasters are more subject to clogging. Filtering the sand is a good idea though I've never seen a decent screen come with them. You can get good screens specifically for this purpose for less than $10. Sand often clumps from moisture and these also break it up.

Media can be salvaged but each reuse cuts effectiveness and there is a much greater reliance on the screen to filter out debris. Also, the recylced sand has picked up moisture and is more subject to clogging. You can use a good Kiddie Play Sand with decent results, cheap enough for one-time use.

Moisture in this operation is even more difficult to control. By now, your are using air that has traveled a long stretch of hose and the air is cooling to condense moisture. Even an at-end filter will not catch it all. You may find, as I did, that I could get maybe 30 minutes heavy blasting before moisture began be a problem. (30 minutes might be all you've got the stamina for, though.)

The usual caveats: The sand will get into everything -- your eyes, hair, nose & clothes. Hoods and respiratory filters are strongly recommended. Blast outside where the sand won't cause problems or can be swept up.
 

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Capt. Mike

Moderator
Air powered spark plug cleaner.

An air powered spark plug cleaner is a mini bead blaster. The spark plug is inserted into a rubber grommet on the top and blasting media, in a small attached bag, is used to sandblast the plug.

Pluses and minuses: On the plus side it does a good job of cleaning the plug. There's a little technique involved but the plug comes out pretty clean, especially as to the removal of caked on carbon and fuel byproducts. Most have a two-position switch that allows a blast of clean air to blow off the worst of the media residue.

On the minus side, if the plug is gunked up with soft oil & wet, the media doesn't work as well. Then the plug needs to be degreased first. A shot of carb cleaner is fine. But dry it again before hitting with the media. The built-in air nozzle is marginal at best and since you don't want sharp media to migrate into your engine, this means the plug must be thoroughly cleaned again in the parts washer or with carb cleaner. And then blown dry. Check around & under the seal washer. (This will also clean the threads so reapply anti-seize before installing.)

Finally, though you may have a clean plug, this does not automatically mean it should be reused. The electrodes may now be rounded or worn. It's probable they will have to be regapped and doing so requires maintaining the appropriate angle and relationship. Some plug designs don't allow this. Plugs using exotic materials, for example the original platinum plugs, can have the rare-metal tips worn or damaged by the media.

[Side story on platinum plugs -- the original platinum plugs were a fairly standard configuration except the center core and the side electrodes were deliberatly short with a tiny dab of almost pure platinum 'soldered' on. I know that's not the right word, but it describes the look. The gap was thus between these two platinum extensions. These plugs were excellent at self-cleaning and used in high-performance engines. They were also very expensive. Last I priced them for my Porsche, they were about $26.50 apiece! But they lasted a long time and kept clean, even with the heavily leaded fuels of the time. But platinum is very soft and the plugs could be easily damaged. Cleaning with a wire brush or harsh blaster would ruin them. Today's platinum plugs are really more Madison Ave. hype than platinum. They have some platinum in the alloy of the electrodes, but it is not the pure platinum of the early designs. (This is NOT the forum to debate whether they are worth it or not.)]

And finally, one must consider cost & effect. You still have a used plug. At the low cost of many of the VW plugs, it might not be worth it to go to all that trouble and time for trying to get another few thousand. Since plugs are part of my 15k service, that means cleaned plugs must go another 15k. By then, I'm pushing it, so I don't bother. I"m paying a little over $2 for my plugs -- is stretching plugs an extra service worth $8? Will difference in gas mileage pay for the plugs?

I tell you one area my plug cleaner IS worth it, and that's small engine, especially 2-cycle plugs. Plugs sitting idle for long periods, plugs subject to gas stabilizers and additives, and plugs burning an oil mix foul quickly. Cleaning restores them. They're not worn as much as just dirty.

For those interested, the media it comes with is a fairly fine glass bead (see bead blaster post above). You can get replacement packs that are good for about two refills. I just scoop a little out of my glass bead tub. They only use about ¼-½ cup. They consume very little air but it must be dry.
 

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Capt. Mike

Moderator
Bead blaster vacuum:

I have the dedicated vacuum for my cabinet blaster. The 'standard' unit; no pre-vacuum media trap, ultra-quiet kit or exhaust filter.

My vacuum started making a terrible racket so I pulled the motor. The ball bearing closest to the cage was toast. There were no signs of lube and it's closest to any abrasive that gets through the filter. The motor was wobbling and the armature hitting the coils. Some talk with electric motor repair folks told me they aren't practical to repair.

TP Tools sells the replacement motor for $80 + $10 S&H. I started a little Internet search and found Lamb Amtek, as installed in mine, apparently dominates the vauum market. One site suggested an alternate made by Domel. Domel is apparently the #2 in the business. Their motor claims a 30% increase in life and cheaper price. Lamb Amteks are rated at 500-800 hours; the Domel at 800-1000 hrs. The Domel also carries a 2-year warranty vs. Lamb Amtek's 1 year.

The site that recommended the subsitution sold it for $10 less, same S&H. i.e. $80 vs. $90. Gasket $4. I then searched for Domel's and found one of the Lighthouse Enterprises dealt in vacuum parts; I undertand this is part of a handicap employment service. They sold the Domel for $60 S&H free; gasket $2.50. My products were shipped next day and the motor works fine and is quiet.

Of course today, I found Grainger (industrial supply) sells the Lamb Amtek motor for $52. Wonder if this will be true for shop vacs? I'll be checking Grainger if mine goes.

[Update 2/1/07: Although my motor arrived timely from Lighthouse Enterprises, the gasket never showed up so I finally had to buy sheet stock and make my own. I have cancelled the gasket order and requested refund. Very disappointing when their "mailed today" wasn't & kept my equipment down for over a week after the motor arrived. Will update again if that turns into a problem.]
 

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Capt. Mike

Moderator
Tumblers

Another way to clean & polish small parts such as hardware is a tumbler. Most were originally developed by the semi-precious gem industry to polish and smooth pieces for jewelry. The ammunition reloading industry discovered them for safely cleaning & polishing used cartridge cases. The won't replace a bead blaster (size & speed) but fishing small parts dropped into the blaster's media hopper isn't much fun, either.

They use a course but non-damaging media, often ground corncob, walnut shell or synthetic. Cases are placed in the tumbler and the tumbler rolls or agitates so the media constantly scrubs the pieces inside the drum or tub. The media is often fortified with jewelers rouge or similar polishing compound.

There are two basic types. One is a drum that rotates. I have this type and have used it for over 30 years. It's slow, but an overnight run leaves the pieces polished and clean without residue.

The second type is the vibrator. It's a basket style on a motorized pedestal that vibrates very rapidly. The pieces literaly shake in the media for a scrubbing action. They are typically quicker than the rotating tumblers.

Thumlers Tumblers http://www.thumlerstumbler.com/ started serving the rock-hound users and I have the equivelent to Thumler's current A-R12 #130. Mine is probably 35 years old, and except for a couple of drive belts for the motor (generic vacuum cleaner belt), it has performed well. They sell both types. Midway USA http://www.midwayusa.com/ is a leading supplier to the reloading consumer and has a huge selection, mostly vibrating.
 

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Capt. Mike

Moderator
Pressue pot sand blasters

The commercial sandblasting companies usual use a pressure pot style sand blaster. These vary in size from about 40 lb. capacity to hundreds of pounds. They will typically use only sand or a commercial abrasive such as Black Magic. The pot is pressurized, thus forcing sand into the air stream so that a combination of air & sand is forced out the gun. This varies slighly from the siphon type which siphons the sand to the gun and mixes the sand & air AT the gun instead of at the source. The presssure pot gives better flow and more consistent media content. These using will require a protective hood and outside air supply as they put out large quantities of sand at very high pressure. However, they are the most effective of all blasters. We used this style on board ship and in the yards, the big units could sandblast the entire hull in a couple of shifts.

A detached spot to sandblast is required. Although sand may be salvaged if in at least a partially confined space, the dust usually makes visibility difficult. Thus home blasters will go outdoors to a spot where a lot of sand won't hurt!
 

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