I have the wire a little
more slack than I would if I were cutting something like wing
cores. This causes the wire to bend away from the advancing foam
and builds up tension in the wire which actually helps achieve
a smoother cut. The tension helps by pulling the wire through
the foam if and when I pause while pushing. I use this bend in
the wire to also judge my cutting speed. If I slow down the wire
straightens out. If I push to fast the wire starts to bend more.
If the bend stays consistent then so is my speed.