Content © 1998 Weber Vintage Sound Technology
Ever wondered how the chassis is produced, chromed, lettered, etc.?
The chassis starts out as a flat sheet of 16ga steel. The quality of the steel
chosen will determine how much work will be required to polish the surface
prior to chroming. The flat chassis is clamped on a large table that is part of
a multi-tool punch press. The punch press is computer controlled so that the
proper punch is selected for each hole in the chassis. After all the holes are
punched, a machine called a sheet metal break is used to bend the sides at
a right angle. The end pieces, which were formed by the same process are
then spot welded into the open ends of the chassis. At this point, the metal
work is finished and the chassis is sent to the chromer.
The chroming process involves several steps, the first being one of the most important.
Before the chassis can be chromed, the surface to be chromed must be buffed to a
very fine finish, almost so fine it looks chromed. The buffing is an art in itself
because it is all done by hand using large buffing wheels. Strangely enough,
large flat surfaces require much more buffing than a rounded metal piece like a
bar stool or bicycle frame. In fact, the latter two are examples of chromed goods
that very seldom get buffed at all. The reason is due to an optical illusion.
Because of refraction of light, the imperfections on a rounded surface aren't
nearly as noticeable as they are on a large flat surface. Generally, chassis
products are finely buffed, however, they usually aren't buffed to the mirror
finish that you would see on something like a shovel used for ground-breaking ceremonies.
After the buffing operation, the chassis is ready to go through the chroming
process. First, the chassis is dipped in several successive tanks of a weak
solution of muratic acid. This eats all the crud, oils, and other contaminates
off the surface of the chassis. Next, the chassis goes through a nickel bath.
This is the most important step because it is the nickel coating that inhibits rust
and corrosion. The depth of the nickel plating determines the ultimate resistance
to the elements. The process is normally measured in terms of the amount of
time the chassis is bathed in the nickel rather than terms such as double or
triple coating, etc. Next comes the actual chrome plating. The chromium
solution is yellow in color and is applied in the same manner as the nickel.
The process is called electrolysis or electroplating. What this means is that a huge power
supply is connected to the bath tank. One of the power supply terminals is
connected to the actual bath liquid, while the other terminal is connected to the
chassis or product that is being dipped. For you tekkies, the electrical
values seen in a typical medium sized tank system is around 6 volts at
over 8,000 amps. Yes, that's 8,000 amps. The current flowing through the
bath solution causes the solution to be attracted to the chassis and sticks
to it, hence it gets plated. Since it's a steady current, you can easily see how
the longer the chassis stays in the bath, the more (and thicker) the plating
goes on. One of the most overused terms for chrome plating is "Triple Chrome Plated"
While the term suggests that the piece to be chromed is run back through
the process three times, it just doesn't work that way. What the marketing
term probably refers to is either the amount of time the product is left in the
bath or that there are three steps in the chroming process. In some instances,
copper is also applied as a layer in the process. So, the irony of the entire process is that
the initial buffing is most responsible for the luster and shine, while the nickel
and chromium are there for protection from the elements. To further illustrate that point,
now that you know how the process works as far as dipping the piece in the bath, etc.,
you can see that the entire piece is actually nickel and chrome plated,
but only the part that has been buffed first appears to be shiney chrome.
Incidentally, if you see a chassis or other chromed product that has holes and there is a definite
ring or discoloration around the holes, it means that the minimum bath times
were used in order to save costs. Since the process involves electrical current
for the plating, the holes are a high resistance, and the plating solution is
attracted and applied at a different rate around the hole as opposed to elsewhere.
The discoloration visual test is generally a tell-tale sign that the product lacks
long term protection from rust and corrosion. All WeberVST chasses are bathed
in both the nickel and chrome baths for twice the amount of time normally alloted
to a commercial product. As a result, the entire chassis appears brightly chromed,
with the buffed control panel area having the highest luster and shine. Also, there is little
evidence of discoloration anywhere on the chassis.
Next on to the screener, or lettering operation.
A picture of the entire lettering layout
is generated with a graphics package on a computer. Next, it is printed out on a special
material called vellum. This special printout is placed on a very finely porous screen material.
The fine screen was originally made of silk, hence the name Silk Screening.
Today, most screeners use a screen made of nylon, and by washing it with special solution,
may be used over and over again for different images.
Through a heat process they call burning, the image is transferred from the vellum printout
to the screen.
What results is that all of the holes in the fine wire screen are plugged except
where the image of the lettering layout is. Next, the screen is layed down
on the chassis and a thick ink is squeegied across the screen several times.
Since the ink is only allowed to go through the screen where the lettering
image is, the proper image is transferred to the chassis face. While most chasses
are screened with the standard silk screening ink, WeberVST's supplier located
a special paint/ink that is much more durable and resistant to chemicals and abrasion.
It is baked on at a higher temperature and for a much longer time than standard ink.