I'd like to thank Fred Jewell <fredj@ksr.com>, who did this entire
section, except the diagram [which took me some time], and the needle
arrangements, which is by Jesster. Please note that this information
is not for the purpose of teaching people how to tattoo, but to
assist in the public in becoming a more well-informed customer.

The tattoo machine ('gun' is a misnomer) is really a basic doorbell
circuit (you know--you push a button and somewhere in the kitchen this
little arm bangs the hell out of a bell thingie). For you techies out
there it's a DC coil and spring point(s) machine. Both doorbell and tat
machine were invented before household current was available.

                 __
                /  \
                \  /  <--rabbit ear w/ a screw in it
              _/ /____
            / /_/     \
           | (   )---\ \
           |  --- ---\\ \
            \/ /_____ \\ \   __     __
           (  )     \ \\ \ /  \   /  \ <--mechanism
           ============================= 
             ^ ------------    |  |    | <-contact points
armature   (| |________________|---\___|
bar ->      | | _/  \_||_/  \_        / <-This whole thing is the base
            | | [XXXX]||[XXXX]__    __ \
coils (X)-> | | |XXXX|--|XXXX|   \ /  \ \
            | | |XXXX|--|XXXX|   / \__/ |
            | | |XXXX|--|XXXX|  /   || /
            =========================== <-rubber bands
            ===========================
          ___| |___|__|__|__|__/ |___((_//
         / //\                       |\-
        | // |    ___________________|
         \// /___/
          ---  |
           |___|
          /XXXXX\
          |XXXXX|
          |XXXXX|
          |XXXXX|  <--sanitary tube
          |XXXXX|
          |XXXXX|
          |_____|
            \  /
             | |
             | |
             | |
             | |
             | |
             \_| <---needles


It is essentially in 3 sections: The base, the mechanism, and the
sanitary tube. The base really is the bulk of the metal; a rabbit ear
with a screw in it, bent at 90 degrees to hold coils. In the front
there's a round hole to hold the sanitary tube.

Some people think the base looks like the handle of a gun. The base
houses the mechanism, which consists of two coils of wire wrapped around
an iron core.

At the top of the mechanism is a set of silver contact "points" (like
the end of a wire); one usually on a spring mechanism, the other either
the end, or on the end of a screw.

The spring connects to the base and a bar, which is connected to the
needle arm (90 degrees offset). The needle arm is connected to the
needles (which are soldered onto the bar), and moves up and down inside
the sanitary tube.

The coils connect to a DC power supply (between 6 - 12VDC), via a spring
coiled U-cable. The U-cable is called a "clip cord," designed to move
easily between machines but also stay in place and not fall out and
spark all over the place. The springs hold the cable in/onto the
machine.

One side of the coils is connected to the power supply, the other end to
the point on the screw on the bunny ear, which is insulated from the
base. Through the points, the current flows via the coils and the base
of the machine. This causes the coils to become electromagnetic. The
electro-magnet pulls down the bar, which does two things: pulls down the
needles, and opens the points. The points being open turn off the
magnet. The spring assembly brings back the bar, which causes the
needles to move up *AND* make contact with the points. This causes the
whole cycle to happen again making the needles go up and down.

Most machines have a large capacitor across the coils/points, which
keeps the points from arcing and pitting, and wearing out so quickly. A
capacitor is a device that holds energy kind of like a battery, but
charges and discharges much faster (parts of a second rather than 3 or 4
hours). The capacitor charges while the points are open, so when they
close, the difference in voltage across them is nill. The points are
really an automatic switch controlled by the spring to turn the thing
off and on quickly. In old cars where there were points there was a
condenser (aka capacitor) for the same reason.

The sanitary tube sucks up the ink in capillary fashion, and the needles
load up as long as there's ink in the small portion of the tube.It's
called "sanitary" because of the cutout at the bottom of the tube, which
can be rinsed out.

My understanding is that there are three layers of skin: Scaly layer,
epidermis, and dermis. Tattoo machines are adjusted to penetrate into
the dermis layer but NOT *through* it (below it is the fat layer of the
body).

When the needles go into the sanitary tube they have a layer of ink on
and between them. The needles make little holes in the skin, and the ink
is deposited into the holes. This is why the skin has to be stretched so
blobs of ink don't stay. Otherwise, the skin will latch onto the
needles, grab the ink from them and generally make a mess.

Ink just put into the scaly layer would be replaced quickly and fade
away. While ink into the epidermis will stay, my conjecture is that the
dermis makes for more ink and perhaps a more vivid image.

Machines are really of two types: Liners, and shaders. They areexactly
the same, but are set up differently. The gap for a liner isaround the
thickness of a dime, and a shader is the thickness of a nickel.

Liner needles are usually arranged on the bar in a circular pattern.
Shader needles are usually straight (like a comb), although Spaulding &
Rogers sells a 15-needle round shader. The needles are small sewing
machine needles, usually made of stainless steel. Liners are in 1, 3, 4,
5, & 7-needle combinations, set in a round configuration. Note: There
can really be any number of them but these seem to be most common.

Shader needles are in a straight row and usually are in groups of 4, 6,
7, 9 needles. The sanitary tubes are designed especially for the
combination of needles, so there's a special tube for each different
number of needles in a needle bar assembly

The following needle diagrams are from Jesse "Jesster" Parent
(jesster@WPI.EDU).

   o is a needle 
   . is a cut down needle (shorter & no point)

Liners:

Single needle     3-needle     5-needle
     o               o            o o
    . .             o o            o
                                  o o

Shaders:

4-needle           6-needle
   oooo             oooooo

8-needle shaders are grouped so that 7 needles form a circle with 1 in
the middle. There are also 14-needle shaders.

8-needle     Magnums:
   o         5-needle       7-needle
  o o          o o            o o o
 o o o        o o o          o o o o
  o o
   o


Shaders are mounted on flat needle bars while liners are mounted on
round bars

There are two other types of machines. Spaulding & Rogers revolution
(don't know of an artist that uses this one), which is a DC motor that
turns a cam that raises and lowers the needle bar assembly through a
sanitary tube. 

The other is the home-made machine made in prison, using a small motor
from a tape recorder or VCR. Here is a picture showing an actual
prison machine that was found by a corrections officer:

http://www.flickr.com/photos/stan7826/313239898/

Chris writes:

"It's really pretty simple. I'm a Corrections Officer and have come
across many machines in the few years I've been an Officer.  Usually
you only find pieces of one, but every now and then you get lucky and
manage to get ahold of a complete machine. After use they break it
down and hide the pieces all over the place.  That way if an officer
finds one piece, they only have to replace that one piece."

"I'll explain it using the pic I sent as a reference.  It's one of the
complete machines I managed to find about a year ago.  It was so nice
I kept it and have used it with some of the academy classes to show
them what to look for."

"In pic "A" you see the entire thing.  The needle at the top, the
machine, and the battery. The needle (B) is usually made from a tiny
spring, like the kind in a Bic lighter, straightened out and then they
work slowly to sharpen one end.  Usually by placing it between a rock
and concrete and pulling the needle out.  This way it's less likely to
bend during sharpening and doesn't become weak."

"The other end of the needle is wrapped into a spiral and the very end
(about 1/16 - 1/8 of an inch) is straightened up and down.  That tiny
straight piece at the end of the spiral is fixed to the edge of the
motor's post. (image C (1) ) It's usually soldered on the top of the
post with melted plastic from a toothbrush or plastic fork stolen from
the dining room.  Because it's placed on one edge when the motor spins
it caused the needle to perform the stabbing motion in and  out of the
tube."

"You can easily see how the toothbrush melted and bend into shape holds
the motor and the tube together.  In this case they used electrical
tape to fix the pieces to the toothbrush."

"In picture "E" you can see the ink tube from the pen has been cut in
half and placed back into the pen's shaft, which holds the needle more
still in the shaft giving it a straighter, more fluid motion as it
goes in and out of the tip. In picture "D" you can see how the "ball"
was removed from the tip of the pen creating a tiny, tight hole for
the needle to pass through."

"And there you have it.  A machine made from less than $3 worth of crap
laying around the house."

"In this case the motor was from a VCR."

"I found this machine while it was being used.  And I have to
say... some of the work that comes out of there is amazing considering
the tools being used."


DO TATTOO NEEDLES BECOME DULL WITH USE? 

The following information is provided by Uncle Bud <uncbud@rmii.com>:

Tattoo needles do not dull with age, but instead become sharper by the
repetitive honing motion they experience in the tattoo machine.
This happens because the metal of the sanitary tube rubs against the
needles, and the softer metal (the needles) will wear. The problem with
these sharpened needles is that they sharpen into flat razor-like edges,
and begin cutting the skin instead of piercing small holes.

Since a tattoo is created by the conical shape of the needle
transferring pigment into the skin with the aid of a wetting agent, the
needle's shape is as important as its sharpness. Pigment does not
transfer into the skin as efficiently when the shape is altered, and can
also lead to scarring.

Another problem with needles is the occurrence of burs or barbs when the
needles hit the side or bottom of the pigment caps.
While it is possible to use the same set of needles for more than eight
hours (on the same client, of course), correct needle configuration,
setup, and alignment of the needle and machine are very critical.