Dovetail Bit Question

[Johnnyy Johnson]

What would be a good size of a 1/2" bit to start with on 3/4 material doing sliding dovetails? 8 degrees?? Does anyone have a Liegh part number?

[Lee Schierer]

I'm not sure I understand the question exactly. I would start with either a dado blade on my TS or a straight cut router bit to remove the bulk of the material before cleaning up the cut with a dovetail bit for the sloped sides.

[Paul Murphy]

What would be a good size of a 1/2" bit to start with on 3/4 material doing sliding dovetails? 8 degrees?? Does anyone have a Liegh part number?
Here is what Leigh has to say on sliding dovetails:
"While virtually any guidebush/dovetail
cutter combination can be used for sliding
dovetails, the cutter angle should be not
less than 12°. We do recommend 8mm
shanks over 1⁄4" for greater stiffness routing
sliding dovetails."
"On a full width joint, the slot depth-of-cut
should be no more than 1⁄3 of the board thickness.
If the tail board is to be a load-bearing
horizontal member (e.g., bookshelf or step),
then make the tail fairly thick to ensure that
the tail neck will be strong.
Shorter sliding dovetails with fewer structural demands
on them may be slightly deeper, with narrower
profiles, especially if appearance is important
(e.g., where narrow rails join wider boards)"

A menu of dovetail bits:
http://www.leighjigs.com/cutters-d4.php

When you ask about 1/2" bit, do you mean shank, or cutting diameter?

[Joe Scharle]

I typically use a 14 deg, 3/4" DT bit for sliding DTs. Allows very shallow neck and a full 3/4" of wood in the slot. Vendors like MLCS and others sell these for around $10.

[Thomas Pender]

I use a 1/2" shank with a 14 degree bit as well, but like Lee suggests, I use a carbide spiral (1/4) to hog out the waste first (for the female part) - makes a much smoother cut with less vibration. Also, I usually run it through more than once. I have used Grizzly bits, Lee Valley, Woodcraft, you name it, to do this and they usually are inexpensive. I have not seen a big quality variation, but I presume you mean to cut these using a router table because that is the only way I know how - I just clamp a piece of scrap as a stop to set my length for the female end and use a big piece of plywood (with many coats of poly for smoothness) with a little hole for the bit to stick out to cut the male end that I clamp to the router table fence with sheets of paper as shims - enables me to finely adjust the size. Sometimes all it takes is two or more passes to make it work.