Another Router Bit question...this time about spiral bits.

Spiral bits are great the direction has to do with which way you want the chips to go . Yes the can be used with a guide bushing. You can use them any time you would be using a straight bit they are great bits and usually reduce the amount of tear out you get.

-- Jim from Heirloom Woodshop, custom furniture ,maker, woodworking school, heirloomwoodshop.com

Thanks Jim.

-- Stevec3606

One of the main differences in up and down is the way it affects the edges of the cut. Up spiral will lift the fibers along the edge sometimes leaving them rough. Down will shear the fibers in a downward cut leaving a cleaner cut. The up spiral tends to pull the bit down and visa versa for the down spiral.
There are spiral bits that have a combination with the first portion being up and the upper part being down giving the best of both functions. I haven’t tried them but the idea looks good, except they are more expensive.

I don’t see any problem using a guide bushing with spiral bits. I do it all the time.

-- Les B, Oregon

A much better explanation of spiral bits Les well done

-- Jim from Heirloom Woodshop, custom furniture ,maker, woodworking school, heirloomwoodshop.com

Also, it depends on what face you are cutting on….the up spiral with make the bottom side clean cut…whereas the down will do the opposite. You also want to use a down spiral when cutting a grove in the face of the wood as it will leave the open edges cleaner….I have both and use them alot….I use them with guide bearings and without..with no problems….they are just as good as bearing guided trim bits…but of course more expensive.

-- Woodworking.....My small slice of heaven!