Router bit mystery

[Jake Helmboldt]

I appologize if this shows up twice, I got an error the first time I tried to post.

I just picked up several dovetail bits for a song. However, I noticed that one of the five has its carbide backwards from the rest. By this I mean, if you look down from the top rather than looking like a Z, it looks like a backwards Z, so it would have to spin backwards for the carbide to cut.

Is there a reason for this? What gives? I hope I didn't waste $2!

thanks, Jake

[Don Baer]

That bit is for cutting the other side of the dovetail..

[Charlie Plesums]

My mortiser spins it's bits "backwards" and my shaper (I don't have a router table any more) is reversible. But I don't know of a reversible router.

[Danny Buie]

Jake,
You probably have a dovetail bit from a multiple spindle production dovetailer. For a ten spindle machine five bits rotate CCW and five CW. Its easier to make two sets of bits than to design, build and maintain a gear train that reverses direction nine times. These machine have been around a long time.

Production multispindle drilling machines work the same way with a right and left hand twist on the bits.

Danny Buie
Baton Rouge

[Chris Padilla]

Pic?? Need pics!!