Tweco CutMaster 12mm-20mm-25mm - Manual (Page 35)

CUTMASTER 12mm, 20mm, 25mm
Manual 0-5117 4T-3 OPERATION
Edge Starting
For edge starts, hold the torch perpendicular to
the workpiece with the front of the tip near (not
touching) the edge of the workpiece at the point
where the cut is to start. When starting at the edge
of the plate, do not pause at the edge and force the
arc to "reach" for the edge of the metal. Establish
the cutting arc as quickly as possible.
Direction of Cut
In the torches, the plasma gas stream swirls as it
leaves the torch to maintain a smooth column of
gas. This swirl effect results in one side of a cut
being more square than the other. Viewed along
the direction of travel, the right side of the cut is
more square than the left.
Right Side
Cut Angle
Left Side
Cut Angle
A-00512
Side Characteristics Of Cut
To make a square - edged cut along an inside
diameter of a circle, the torch should move coun-
terclockwise around the circle. To keep the square
edge along an outside diameter cut, the torch
should travel in a clockwise direction.
Dross
When dross is present on carbon steel, it is com-
monly referred to as either “high speed, slow
speed, or top dross”. Dross present on top of
the plate is normally caused by too great a torch
to plate distance. "Top dross" is normally very
easy to remove and can often be wiped off with
a welding glove. "Slow speed dross" is normally
present on the bottom edge of the plate. It can vary
from a light to heavy bead, but does not adhere
tightly to the cut edge, and can be easily scraped
off. "High speed dross" usually forms a narrow
bead along the bottom of the cut edge and is very
difficult to remove. When cutting a troublesome
steel, it is sometimes useful to reduce the cutting
speed to produce "slow speed dross". Any resul-
tant cleanup can be accomplished by scraping,
not grinding.
4T.04 Hand Torch Operation
Standoff Cutting With Hand Torch
NOTE
For best performance and parts life,
always use the correct parts for the type of
operation.
1. The torch can be comfortably held in one
hand or steadied with two hands. Position
the hand to press the Trigger on the torch
handle. With the hand torch, the hand
may be positioned close to the torch head
for maximum control or near the back end
for maximum heat protection. Choose the
holding technique that feels most comfort-
able and allows good control and move-
ment.
NOTE
The tip should never come in contact with
the workpiece except during drag cutting
operations.
2. Depending on the cutting operation, do one
of the following:
a. For edge starts, hold the torch perpen-
dicular to the workpiece with the front
of the tip on the edge of the workpiece
at the point where the cut is to start.
b. For standoff cutting, hold the torch 1/8
- 3/8 in (3-9 mm) from the workpiece
as shown below.