Spirals are the ONLY way for me to cut portraits!
Lots of TENSION, fast blade speed and don't 'feed' the wood, just GUIDE it SLOWLY.
They are not easy to deal with and you MUST have at least 3/8" STACK to be able to control them. Trying to do a single 1/8" or 1/4" with spirals is to invite major disaster.
~~~GB~~~