Blast Cabinet Part 1

Copyright © 2005 Dave Propst. All rights reserved.

Revised 6/01/2005

Introduction

This article is the first in a three-part series of articles describing a large abrasive blast cabinet.

Blast Cabinet Part 1

Blast Cabinet Part 2 - Details

Blast Cabinet Part 3 - Function

This, the first article, contains pictures and detailed descriptions of all aspects of the overall cabinet. The second article is a collection of close-up pictures of various design details of the abrasive blast cabinet. The third article contains a lengthy and very highly detailed explanation of media blasting sheetmetal automotive body panels.

Photographing a piece of equipment this large with flat, angular surfaces that are bright white in color is no easy task. The problem is finding a happy medium between losing details in shadows and 'blowing out' some of the large surface areas of the glossy bright white cabinet as the camera picks up glare from lights.  In order to insure that no details of construction are lost to underexposure in darker corners, some of the pictures show pronounced glare on the cabinet surfaces and background wall.

General Description of Blaster

This abrasive blasting cabinet is built specifically for media blasting of automotive body panels. It has been in almost daily use since 1987. While it certainly can be used to blast items other than sheetmetal panels, it is optimized for that purpose. This optimization includes the method of loading parts, the operator's view of parts inside of the cabinet, the operator's access to those parts, and a few other specifics.

The cabinet panels are constructed of 18 gauge steel sheet. The leg framework is of 1x1x1/8 and 1x2x1/8 steel tubing.

In the configuration seen in the picture below, the cabinet's dimensions are as follows. These measurements are of the main cabinet structure. They do not include the moveable front panel.

1. Overall exterior size:  8' 4" wide  x  3' 8" deep  x  6' 2" tall.

2. Actual inner size for a workpiece stood up at 90 degrees:  72" wide  x  36" deep  x  32" tall.

3. Actual inner size for a workpiece angled at 45 degrees:  72" wide  x  36" deep  x  36" tall.

4. For reference-- the car fender that appears in a couple of the pictures is approximately 61 inches in length.

 

A second configuration capable of dealing with much larger parts is shown at the end of this article.

Split Level Cabinet

Instead of having an end-loading door for insertion of items to be blasted, the entire upper portion of the cabinet is hinged and spring assisted to pivot open for loading of parts. While such so-called 'split level' blast cabinets are more expensive to buy --or more complicated to build-- they do offer advantages when cleaning body panels.

One advantage is simply that it is easier to load and position a part such as the large front fender in the pictures on the blaster's grate. It is simply a matter of carrying the panel to the blaster and laying it down on the grate in the position desired. Certainly it is possible to insert and position such a body panel through an end-loading door. However, it can be quite annoying when flanges or corners of the panel interlock with holes in the grate as it is being slid into the cabinet. At times it is necessary to reach into the cabinet through the gloves and 'hop and skip' the panel into place, then get out of the gloves, close the door, then get back into the gloves to begin blasting. To be able to just lay the part down in the position desired, pivot the cabinet shut and start blasting is much easier.

Another advantage is the ease with which a part can be inspected. No matter how well filtered and lighted a blast cabinet is, in the course of blasting a part, especially a large and awkward body panel, there comes a point when it is necessary to do a close-up inspection in good light at angles not possible through the cabinet's window. In other words, there is a need to get the part out in the open and roll it around for inspection and discovery of areas that need more attention. With the end-loading door setup this means pulling the panel out of the cabinet, carrying it to a bench, table, or open space on the floor, inspecting it, and then going back through the motions of inserting it into the cabinet. All-in-all quite a bit more time consuming than simply pivoting open the cabinet to expose the panel to shop light, inspecting and even moving the panel around to see it at different angles right on the grate, then closing the cabinet and continuing on with blasting.

Movable Front Panel

The next three pictures show the moveable front glove panel and the large viewing window.

The movable glove panel is made of 16 gauge 6061 aluminum. It allows the operator to position himself anywhere across the width of the cabinet. During operation, there is no need to remove arms from the gloves to adjust the glove panel. Just a little sideways push with one's elbows and the panel slides to whatever location is desired. When blasting autobody parts this is extremely advantageous.

Many large blast cabinets have two sets of gloves, one set on either side of the front of the cabinet. While that setup is (usually) more helpful than merely one centered set of gloves, it still restricts movement and makes for greater operator fatigue. A particular problem is that having one set of gloves in fixed positions on either side of the cabinet means that there are no glove positions in the center of the cabinet! When blasting a fender such as the one pictured here, imagine the tiring, stretched-out arm, left-handed work (or vice-versa for left-handed operators) required to reach all of the middle portions of the fender. Removing the fender, swapping ends and inserting it back into the cabinet in the other direction does not help in this instance because the middle of the fender is still the middle of the fender. When having to hold such awkward work positions for extended periods, fatigue becomes a real issue. The moveable glove panel eliminates such awkward positions but it goes beyond that. Any position, even one that is initially comfortable can become tiring after a time. If the operator tires of one position, or just wants to trade the blaster gun to his other hand but still blast the same part of the fender, he can simply move the glove panel to a new position. Given the large window glass area he can also move to a new viewing angle while continuing to blast the very same area of the workpiece.

The pictures show the gloves in centered, left, and right positions. These positions are not mandatory detents. In other words the panel can be moved to not just these three positions but to any position anywhere along its entire travel. The left and right positions in the pictures are not even the extreme limits of travel. The panel can be moved until the glove retainer hits the corner of the cabinet-- meaning there is a couple more inches of travel than seen in the pictures. There is actually a one-inch wide gasket flange on the cabinet end walls, so, to be technically correct, the glove can be positioned against that flange one inch from the actual outside corner of the cabinet. This 'arm-all-the-way-into-the-corner' capability is very helpful in blasting the ends, edges and sides of large, flat panels such as hoods, deck lids, and quarter panels. The window comes into play here too. Unlike the traditional framed windows of most commercial blasters, the glass extends all the way to the corner of the cabinet. Consequently, the operator can see what the blaster gun is doing to that hood edge or deck lid edge that is in close proximity to the end of the cabinet. So... not only can the operator put his arm all the way against the end wall of the cabinet and to at least some degree around the end of the workpiece, he can also see what is occurring while doing so.

Ergonomics

Note that the cabinet is at just the right height to avoid bad posture.

A quick look back at previous pictures will show that the glove attachment holes are oblong. That is, they are taller than they are wide. Many commercially-made cabinets have glove openings that are round. That provides maximum freedom of movement vertically and horizontally for the operator's arms. However, since with this cabinet the entire front glove panel can be moved anywhere in the width of the cabinet, there is no need to allow for any extra horizontal movement of the operator's elbows within the glove opening. That extra glove opening width can be 'stolen' and applied to the height of the opening. Furthermore the entire glove panel can not only move horizontally it can move vertically some small amount and float in that position without being manually held up. This all means that while handling the blaster gun and moving the workpiece around, the operator can change the angle and vertical height of his arms some fair amount before his elbows are restricted.

The operator rests his upper arms and chest against the protruding seal-cover/body-rest across the front of the cabinet. This creates a three-point braced stance (two feet + one upper body). This forces the operator to use upper arm strength (biceps) instead of lower back muscles to both hold up the continuous weight of the blaster gun and hose as well as the weight of heavy workpieces as they are moved to new positions within the cabinet.

The width of the glass is the same as the width of the main cabinet workspace structure, 72 inches. Height of the glass is about 14.5 inches. About 0.75 inches of glass is covered by the glass retention framework, at top and bottom, so about 13.0 inches of clear aperture (viewing area) is available. The angle of the window glass is approximately 45 degrees, whereas many commercially-made cabinets have a much more vertical glass. This window angle and size is helpful. When blasting small mechanical parts or even small sheetmetal parts it is common practice to pick the part up with one arm/glove and blast it while holding the blaster gun in the other arm/glove. That simply is not possible with large, heavy objects such as a fender or a major chassis part. Since it is not really practical or even possible to pick up a large fender in one had and turn it about while blasting it, the fender must lay on the blaster grate or work surface. This means it is necessary to be able to blast (and observe) surfaces over a wide area from high up in the cabinet to down low near the grate just in front of the front wall of the cabinet. The 45 degree angled window is pretty well positioned for a line of sight looking down at those very areas of a large workpiece such as the fender. As can be seen in the picture, externally the 45 degree angled window provides ample room for the operator to tilt his head down to look at the front of the workpiece without pressing forehead or nose onto the glass. By contrast the smaller, much more vertical windows of some blasters are well suited for observing the upper half of the back wall of the cabinet! Seriously though, they may be well suited for the scenario described above of picking up smaller, lighter parts and holding them in one hand at optimum viewing height while holding the blaster gun in the other, but, they are not well suited for working with large body panels. Again, this blast cabinet is designed from top to bottom for blasting large body panels.

Miscellaneous Views and Features

The next picture is the left end view of the cabinet.

Next is the right end view.

The next picture is the right rear three-quarter view showing many of the features of the cabinet.

The blower mounted on the end of the cabinet is part of the filtration system. This system is explained in detail in a later section of this article. For now just note that its intake is connected to the ductwork it is mounted on and its exhaust side is connected to the wall of the cabinet.

The long, black horizontal object across the rear is the assist spring for the cabinet pivot hinge. It is actually a garage door opener spring and associated hardware.

The device mounted low on the rear of the cabinet's abrasive hopper is an electric shaker motor and its protective cover. It assists in returning the abrasive to the very bottom of the hopper.

Relatively low blaster gun pressures are used and relatively large gun nozzles are usually used. In order to deliver ample volume of air flow to the gun at those low pressures, 1/2-inch hoses, 1/2-inch tubing and large Tru-Flate couplings are used throughout the cabinet air supply system downstream of the high pressure shop air supply.

Lighting System

The following picture is the left rear three-quarter view with the cabinet in the opened position showing the florescent light case and the filtration system.

A common blast cabinet lighting setup is a pair of hanging utility lamps (socket and bulb). There are several disadvantages in that. Such light is very directional, thereby creating more pronounced extremes of dark and bright areas-- meaning shadows. In the dusty conditions of a blast cabinet though, the less even the lighting is, the more difficulty the operator has in seeing how clean the part's surface is becoming. Another problem is that the hanging fixture can at times get knocked around while moving parts in and out of the cabinet or while moving parts to new positions during blasting. Also, some light fixtures used are susceptible to the blast abrasive eventually getting into the threads of the light bulb and light bulb socket. Bulb changes can then be problematic.

To avoid those disadvantages just mentioned, the trapezoidal shaped peak of the cabinet contains a 2-tube, 72" florescent fixture. A tempered glass separates this light fixture case from the cabinet so as to prevent abrasive from entering. All of the lighting fixture is recessed in the light case behind the glass. Nothing hangs down into the work area of the cabinet. The florescent tubes run the full length of the cabinet. Light is aimed down into the work area for the continuous length of the cabinet instead of emanating from two concentrated locations (light bulbs).

Filtration System

This cabinet is used primarily for rust removal. It is not designed for paint stripping. This is explained in detail in the third article in this series. Since the cabinet is not used for extensive paint stripping, its filtration system is not designed for contending with large amounts of paint debris. Instead, it is designed to deal with large amounts of dust. This is because rust stripping creates considerable amounts of thick, dark dust. The filtration system also needs to efficiently deal with the very large volume of the cabinet interior with respect to that dust.

A filter system is used instead of a cyclonic separator. The system consists of three separate features-- a debris screen, a filtered circulating airflow system and a vacuum.

1. Debris screen: Inside the main cabinet workspace area is a grate. This grate holds the part being blasted. Below this grate, about halfway down into the main hopper is a large screen filter.

2. Circulating airflow system: On the end of the cabinet shown in the picture above is a box-shaped air duct with a bolt-on lid. Contained in this box beneath the bolt-on lid are dust collection filters. The bottom of this filter box forms a funnel-shaped hopper independent of the main hopper of the cabinet. An airflow duct on the rear of the cabinet is connected to the filter box. This duct runs the entire length of the rear of the cabinet. It then wraps around the other end of the cabinet. This is the duct on which the blower fan (seen in previous pictures) is mounted.

3. Vacuum: This is merely a small, low-power shop vac ported to the main cabinet interior.
    

As the blast gun is expelling air and abrasive, most of that abrasive and any large particles of debris fall to the screen below. Large debris particles are trapped by the screen but the abrasive immediately falls through the screen into the bottom of the hopper. Eventually, as work progresses, the abrasive again enters the gun's pickup tube and is reused.

In a rust stripping operation, most of the debris particles are so small and light they remain airborne instead of falling to the screen below. This airborne debris is extremely fine iron oxide (rust) dust, abrasive particle dust and any other airborne particles. The blower mounted on the right-side end of the cabinet forces air and this dust out of the cabinet interior and through a vent in the left-side cabinet wall leading into the filter box. The filters collect particulate matter of a certain size and larger preventing it from traveling into the airflow duct. These filters are never cleaned or replaced. Instead, assisted by a shaker, the dust particles fall off of the filters into the hopper below the filter box. This material is then periodically dumped from the filter hopper. This hopper is quite large so it needs to be emptied only about once per 50 hours of actual blasting time. Air from the blower is able to pass through the filters and continue on through the long duct on the rear of the cabinet. It travels into the short duct on the right-side end of the cabinet on which the blower intake is mounted. The blower pulls air from the duct and forces it into the cabinet interior wherein the process begins over. A frequent procedure is to never drain used abrasive from the main hopper. New abrasive is merely added to the hopper periodically as old abrasive is consumed by the system to eventually becomes dust in the filter hopper.

The shop vac attached to the cabinet actually collects very little dust. The majority of the dust is collected by the circulating airflow system. The shop vac's main purpose is to create negative pressure in the cabinet interior. While the circulating airflow system is continuously circulating air through the cabinet, the blaster gun constantly introduces compressed air into the cabinet. This means the cabinet interior would have positive pressure higher than ambient air pressure in the shop. However, the small shop vac prevents positive pressure from building up. The result is that whenever the shop vac is turned on while blasting is in progress, the cabinet interior is under considerable negative pressure relative to the shop ambient air pressure. This negative internal pressure assists in making the cabinet dust-tight such that dust is not expelled into the shop. The tilting upper cabinet structure has a seal which mates to the perimeter of the base (hopper) structure. The sliding front glove panel also has seals. These seals are designed such that the negative pressure inside the cabinet causes both the hinged upper cabinet structure and the sliding front panel to be forced against their respective seals instead of drawn away from them. Additionally the shop vac's exhaust heat and odors are ducted by hose outside the shop. The end result is that little if any dust, odor, or heat is expelled into the shop.

Cabinet Size Comparisons

The next series of pictures will show the cabinet in an optional configuration. This setup is used for blasting body panels larger than the fender shown inside the cabinet in previous pictures. Before getting to those pictures however, an explanation is offered of why all larger-than-normal cabinets are not equally suited for working with auto body panels. After considering the dimensions presented and the work restrictions they represent, it will be apparent why the cabinet in this article was designed the way it was. (This discussion is quite detailed and may be of interest only to those wanting to buy or build a blast cabinet. To skip over this section, simply scroll down to the next photograph.)

The problem with using common commercially made cabinets for blasting automotive body panels is that they are not really designed with this specific task in mind. Consequently, their configuration presents restrictions as far as what size body panel can be inserted and how much of that panel can actually be blasted. To better understand this, realize that in the world of blast cabinets at least two separate, distinct marketplaces exist. As a generalization, and for lack of better names, one could be called 'industrial' and the other might be called 'consumer-oriented'.

Note: This discussion cannot possibly include actual dimensions of all car parts and all blast cabinets. Instead, only a few dimensions are given. Actual measurements of a few popular car parts are listed. The blast cabinet dimensions that are provided are the result of an averaging of the measurements from a few popular manufactured units. Manufactured cabinets of the type and capacity discussed are in fact quite similar to each other in cabinet measurement and cabinet design. So, while the cabinet dimensions stated here do not represent a single specific cabinet, they are very typical of what is available.

Industrial Cabinets.

Industrial blast cabinets are purchased by manufacturers, heavy fabricators, major powder coat and other surface finish facilities, and any business that has very specific and/or extreme needs. These cabinets are usually designed from top to bottom for heavy duty, continuous, all-day use. A large selection of sizes is available as a standard design. Additionally, most any size and configuration imaginable can be custom ordered. Designs can be so extremely task-specific that they would be of little value for general usage. Much more elaborate dust extraction and media reclaim features are available than are found in the consumer-oriented market. Cabinets in this market are available for use with any blast media-- everything from silica flour or soda to large, heavy, steel shot. Relative to the cost of cabinets in the consumer market, these cabinets can be very high in price because of their more elaborate design, continuous duty cycle performance characteristics, and often larger size.

Consumer Cabinets.

Most all cabinets owned by hobbyists, restoration shops and rod builders fall into this category. There are only a few manufacturers specializing in such consumer-oriented cabinets but many such cabinets are built. These companies use mass-mailing and similar methods to market to automotive and motorcycle oriented hobbyists, pro or semi-pro restoration shops, rod shops, parts rebuilders, machine shops, aircraft repair, etc.. These blast cabinets are neither elaborate nor task-specific. They are basic, simple, relatively inexpensive units of a more-or-less generic, standard design. Most are designed for intermittent use only. Cabinets with work area widths up to about eight feet are available. Work area maximum depth and maximum height is limited to about three feet or slightly less-- much smaller than industrial cabinets. End-loading access doors are the norm. Few, if any split-level cabinets are made by most manufacturers specializing in this market. These cabinets are designed to use common blast media such a silica sand, silicon carbide, aluminum oxide, common types of plastic media, walnut shell, etc.

Previously it was stated that... "A problem with using common commercially made cabinets for blasting automotive body panels is that they are not really designed with this specific task in mind." This is reference to consumer-oriented cabinets (as just defined) not to task-specific industrial cabinets that may be well-suited for working with body panels. Looking at the consumer-type cabinet in more detail...

Consumer-type Cabinet Size Limitations

While there are units made that are exceptions to the following averaged dimensions for consumer-type cabinets, typically a manufacturer's largest work area height option is about 36". The largest depth offered is slightly less than 36". Typical width of these largest-height/largest-depth optioned cabinets is four or five feet. For customers wanting cabinets with more capacity than this, manufacturers build essentially the same cabinet but with added width and dual glove sets (fixed position) in the front panel. This increases the work area width into the six to eight foot range but leaves the work area height and depth at the 36" range. Alternatively, cabinet extensions are available for attachment to shorter cabinets at the end door opening. This provides more work area, but, again, in cabinet width only. This increase in work area width accomplishes little when working with auto body panels. The work area height and depth are the 'weak link' restrictions. That is what needs to be larger. However... the problem is even more acute than a first impression would indicate. End loading blast cabinet doors add to the problem.

When comparing sizes of cabinets that have end-loading doors, it is important to realize that quite often the cabinet's door opening jamb framework is smaller than the cabinet's internal work area dimensions. The cabinet internal dimensions are often the size played up in advertised specs. Sometimes the smaller door jamb opening size is mentioned only in the 'fine print'. It is however the cabinet's door opening size that determines how large an auto body panel can be inserted into the cabinet. This does not mean the manufacturer is trying to deceive buyers. After all, the smaller door opening is of little concern for the general use blasting for which such cabinets are marketed. That is to say that, usually, advertising claims are that the cabinet is for cleaning common items from wheels to suspension parts to engine parts -- not gigantic hoods from ''60's or '70's era Cadillac and Lincoln cars for example.

Now consider what auto body parts might or might not actually fit into a large consumer-type cabinet... even an eight foot wide cabinet.

Cabinet opening.

The size of the door opening in the cabinet will be used for the comparison with various car body panels. The typical maximum sized consumer-type cabinet shows around 32" inches at the bottom of the opening (depth) and around 34" inches at the rear of the opening (height). This gives a bottom front corner to top rear corner diagonal of around 45" or 46". This diagonal represents the maximum dimension of the opening. In other words consider a body panel dimension that is larger than the 32"  depth and larger than the 34" height of the opening. If this part is to be inserted into the cabinet, the logical technique is to insert it through the opening at a diagonal.

Miscellaneous body parts.

Certainly long, narrow panels such as valence panels, filler panels, package trays and the like will all easily fit and can easily be blasted over their entire surface.

Fenders.

Many fenders will fit in lengthwise as long as the cabinet is wider than the fender is long. Even fenders that are quite tall can be inserted by taking advantage of the fender's wheel opening to help clear the cabinet door opening. However, for progressively larger fender sizes, even if they fit into the cabinet, getting the entire fender surface blasted becomes more and more difficult. The larger the fender, the less room there is for maneuvering the blast gun and the fender itself so as to blast the entire surface.

Doors.

It might appear doors would be no problem but such is not always the case. Here are dimensions of some typical car doors:

1. '69 - '70 Mustang: 51.5" length x 23.0" height (4.0" to 5.0" thick at top/bottom jamb, 6.5" thick at front/rear jamb)

2. '40 Ford coupe: 36.0" length x 46.0" height (approx 2.0" to 3.0" thick at all jambs)

3. '40 Willys coupe: 41.5" length x 46.5" height (approx 2.0" to 3.0" thick at all jambs)

4. Typical later model full-size pickup: 44.5" length x 50.0" height (2.0" to 4.0" thick at top/bottom jamb, 6.0" thick at front/rear jamb)
    

Analyzing each of these for fit in consumer-type cabinets:

1. The Mustang doors have removable window frame structure, leaving only 23.0" of height. Doors such as this will easily fit lengthwise into the cabinet. Even though the doors cannot be stood on end in the cabinet (because of the door's 51.5" length), usually all surfaces of the door can be blasted.

2. At 36.0", the length of the Ford coupe door would easily fit in the cabinet opening diagonal, so the door could go in that way. It might be assumed that the door's 46.0" height could perhaps just slide in the 46.0" cabinet opening also but that is not the case. Car doors aren't two-dimensional. They have thickness also. The 2.0" to 3.0" thickness of this door at the jambs will prevent the door from fitting through the square, 90 degree inside corners of the the cabinet opening. This because the 45.0" to 46.0" diagonal is only available at the one point at the very centerline of the diagonally opposite corners of the opening.

3. Given it's jamb thickness, the Willys door's length would also likely fit into the cabinet. It's height would not.

4. Given its size and greater thickness at the jambs, the full-size pickup door would likely not fit into the cabinet at all.
    

Quarter Panels

Many quarter panels are too large in length/height combination to fit into the cabinet. Exceptions would be very long ones having less height. Examples are quarter panels from '50's and '60's era full-size two-door convertibles. Many such panels would fit as long as the cabinet is wider than the quarter panel is long enough.

Hoods and Deck Lids

Most hoods and most deck lids of cars from 1950 and later are large enough to not even come close to fitting in a blast cabinet such as this. Older car hoods, of course, are made of up of four parts hinged together. Each separate part would fit in the cabinet. Many smaller deck lids would fit.

Finally a few conclusions can be made about using consumer-type blast cabinets for blasting auto body panels:

That a panel will fit into a cabinet is no guarantee that it can be blasted over its entire surface. An example would be a panel like the '40 Willys coupe door mentioned above. It will fit into the cabinet one way but not the other. In the direction in which it will fit into the cabinet, it is a tight fit across the diagonal of the cabinet interior workspace (bottom front to top rear). Given such a restriction to movement into different positions for blasting, such a panel probably could not be blasted over its entire surface.

End loading cabinet doors limit maximum size of the workpiece to something less than the actual cabinet internal workspace size. Note that there is no cabinet door or cabinet door jamb size restriction for a split-level cabinet. The actual inside workspace size is the true limiting restriction-- not an access door framework.

In comparison to large split-level cabinets, the combination of too-small work space and end-loading cabinet doors of these consumer-type cabinets do add significantly to labor times required to blast the entire surface of those body panels that can be inserted into the cabinet.

Cabinet Extension for Larger Capacity

In this first picture note that mounted on the cabinet between the light case on top and the filtration duct on the rear is another attached sheetmetal structure.

This panel is removable and can be replaced with an alternate structure.

This cabinet extension is bolted on when greater capacity is needed in order to blast larger body panels such as hoods and quarter panels. In this configuration the cabinet grows to almost 8 feet high. This extension has its own hinged lid that can be used for insertion of parts , but, in most cases even very large parts can still be inserted by tilting the cabinet open.

Additional helper legs are needed to keep the cabinet stable when it is pivoted open with this extension attached.

These additions bring the workpiece capacity up to whatever can be inserted into a 60" height x 72" width x (varying) depth. Depth now varies from the cabinet's 36" depth to the extension's necked down section of 14" to the extension's hinged lid opening of 19".

Finally, consider some specifics about what body panels will fit into the cabinet with the extension attached.

Fenders and Doors

Once in the cabinet, most boxy-shaped fenders such as the one in some of the pictures in this article can be rotated as needed for complete blasting of all surfaces.

By making use of the cabinet extension, taller, flatter shaped fenders such as old-car rear fenders as well as all doors, can be rotated 360 degress while blasting all of one side without having to open the cabinet. Once all of one side is blasted, the cabinet is then opened, the part is flipped over and the cabinet is closed. The part is then rotated 360 degrees while blasting all surfaces of that side.

Hoods, Deck Lids and Quarters

Large, flat panels such as hoods, deck lids and quarter panels are handled in much the same way as doors except that, depending on just how large the panel is, it may not be possible to rotate the part 360 degrees with the cabinet closed. In that case the cabinet needs to be opened not only to flip the panel over front to rear, but to rotate the panel to new blasting positions. However, recall that opening the split-level cabinet to reposition a body panel is a very easy and fast process in comparison to dealing with a body panel in an end-loading cabinet.

In the most extreme case the body panel may be not only too large to be rotated while the cabinet is closed, it may be too large to fit in both directions. For example, say the panel in question measures 60" wide x 70" long. The panel is too big to be rotated while in the 60" x 72" work area. It is also too big to fit if removed from the cabinet, rotated only 90 degrees, and inserted back in the cabinet. It must be rotated 180 degrees at a time. Another way to state this --perhaps a little more clearly-- would be that a panel this large will fit in the cabinet if laid on it's side but not when stood on end. It can still be blasted though. Here's how. The extension is 24" tall. That means the even in the case of a 60" tall panel only a maximum of 24" of it is hidden inside the extension. The other 36 inches is accessible inside the main cabinet workspace. The extension and therefore the panel being blasted is angled at 45 degrees. So... it is not as if the operator is required to reach horizontally out across the workpiece all of those 36 inches. Even at the 45 degree angle though, usually it is not possible to reach all 36 inches with the blaster gun. However, it is always possible to reach at least 30 inches. It is also possible to reach all of the perimeter edge of the workpiece that is resting on the grate just in front of the sliding front panel as well as up both sides near the left and right cabinet walls. That accessed and blasted area amounts to at least half and usually more than half of the 60" maximum panel height. Consequently, by blasting half of the panel, removing it, rotating it 180 and then blasting the other half, the entire area of a panel as large as will fit into the 60" height x 72" width can be blasted. It can then be removed from the cabinet, flipped over and then inserted back into the cabinet to blast the other side.

This cabinet can easily handle any common automotive hood, trunk lid, fender or door as well as many quarter panels. On the other hand, most consumer-type manufactured blast cabinets, even eight-foot wide ones, are far too small to be used to blast most one-piece hoods, most trunk lids, most quarter panels, many fenders and many doors. The difference in capability is considerable.

In all probability there is a variation of Murphy's Law that states, "No matter how big a blast cabinet is, the body panel most in need of blasting will be 1/2" too large to fit." Even so, this cabinet is a good compromise between maximizing cabinet internal workspace size and minimizing required shop floor space. 

End of Article