Howdy Marg,

 What I learned was to run your fingers up and down on the blade. By doing this, you can feel if the blade goes against your finger, if your finger feels like its going against the direction of the spiral while you slide your finger up, then thats the correct way. You wont tear the wood on the top. If you reverse this method, you will see the wood start to splinter on top. I hope this answers your question. If anyone has an easier way of determining which way is the correct way, please let me know. This is the only way I know of, but then, I'm not a professional....   LOL!      Mark   aka: "The balding fireman"  "the balding scroller"

Marg,

Mark's method of determining which direction the teeth run on a spiral works for me too. Other than using a magnifying glass, I found that to be the simplest way.

The spirals create a slightly larger kerf than the same number in a flat blade.

Generally I just use the spirals on up to 1/2" thick wood and stick to #1's and 3's of the Flying Dutchman New Spirals. (I found the new spirals from Mike easier to control, cut better, and last longer than any other)

 

Tom