Quickie Q2 Lite Construction Manual - page 43
Q2 Plans - Chapter 3 - Page 3-07
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The use of the hot wire saw is a simple thing if your equipment
is set up properly. Proper wire tension and wire temperature should be
maintained for good cutting. The wire tension should be tightened
after the wire is hot by twisting one tube with a pair of pliers. The
wire should be as tight as possible. The wire should be hot enough to
cut one inch of foam in four to six seconds without having to force
the wire. A wire that is too hot will burn the foam away excessively.
To cool an over-heated wire, simply turn your voltage control to a
lower voltage setting. If you use a battery charger, you will have to
add length to the wire. To warm up a cool wire, just increase the
voltage setting or, with the charger, shorten the wire. Although the
foam offers only mild resistance to the hot wire, a long cut will
cause the middle of your wire to lag behind the ends. Wire lag can
cause problems in tight curves like the leading edge of an airfoil. To
reduce lag there, the cutting speed is reduced to about one inch in 8
to 10 seconds. The airfoil templates have notations in the areas where
reduced speed cutting is necessary and pause marks where it is
necessary to allow the lag to catch up completely.
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The most common hot wire error is wire lag which causes a bow in
the leading edge. The following method solves this problem and thus we
recommend you use it for cutting the canard and wing. Use the tabs on
the templates at the waterline at the leading edge by cutting the core
in two passes: one from the leading edge up over the top to the
trailing edge, the other from the leading edge (under the tab) down
under to bottom to the trailing edge. The thin flashing of foam left
on the leading edge due to the thickness of the tab is easily removed
with your butcher knife. The result is a perfectly straight leading
edge. Care must be taken to assure that both ends simultaneously
approach the template at the leading edge. Use the following vocal
commands “wire is moving toward the tab, now resting on the tab 1/2
inch from the template (confirm both ends in that position), moving
toward template 1/4 inch away, 1/8" away, on the template, moving up
(talking number), Y (talking number)...” When approaching the trailing
edge overlap notch (see sketch) slow down and pause 3 seconds in the
notch to assure a full, sharp, accurate surface for the skin overlap.