Spiral bade can be very tricky to use ! If you are new to scrolling they can ruin your day in heart beat so my suggestiong is to not use them if you are just starting out, If you Sneeze it can go bad for you. The design of blade is like a round rasp that gouges wood when you use it.
I have made a couple of dulcimers were I used them for just the purpose you mentioned to overcome the 16" problem in cutting sound holes. I have found when it get a little hard to handle slow the saw way down you are not in race to finish it right. The Thickness of the wood can make a difference in how well any blade preforms . at 1/4 inch you may consider stack cutting and if you didnt want two or more give it Aunt whats her name she loves everything.
I found a trick over Christmas season. I was having a difficult time cutting Oak 1" thick. The blades I had Kept wowing becuase it need more pressure to cut. I could no get a 90 degree straight up and down cut it would be either way in at the bottom or way out of the bondreries( I cant spell either). Late at nite no way to get more blades I grabed a spiral blade and found that it was perfect for the task. It cut square and allowed me control to true up my mangled mess in the other cuts.
Don't know if this helps any but that is my tip for the day
Carl
