I learned something interesting today

[lcm1947]

I read this in a magazine today. I think it was " Fine Woodworking ". Anyway to cut a dado here's one way you can do it: Clamp a fence ( board ) down on the board to be dabo'ed and then place a board that is the same size as the bit next to the fence so it's between the fence and the router bit. You then route the dabo using the board as your straight edge for the router. You then take away the board that was the same size as the router bit and replace it with a board the size you want the dabo to be next to the fence where the other board was. Then route again which will give you the dado the size you wanted. This works with any size dado as long as the first board is the same size as your bit. Now I haven't thought it through all the way but that's what the article said and hopefully I've remembered it correctly. So if it truly works it would eliminate having to make up any type of straight edge as you would normally do to cut a dado. Anyway thought I'd mention it as I thought it was pretty cool.

[Thom2]

I've used the same principle on the router table ... it works pretty well ....



IIRC, the smaller one was two passes with a 1/4" bit, and the larger was 2 passes with a 3/4" bit.

[bigsteel15]

Saw it, tagged it, plan to use it first chance I get.
Takes the thinking out of trying to layout dados.

[IBBugsy]

I'm too much of a novice to understand this???

[scorrpio]

You then route the dabo using the board as your straight edge for the router.. . . . .So if it truly works it would eliminate having to make up any type of straight edge as you would normally do to cut a dado.

Something doesn't sound right there...

Also, while you usually will have on hand a board as thick as the dado (that would be the stock going INTO the dado), keepin on hand a board milled precisely to bit thickness? And you still need to properly lay out at least one side of the dado, and clamp a fence just right.

Here's a technique: clamp a board along one side of dado-to be. 1x4 works well for this. Now, clamp another 1x4 using the stock going into the dado as a spacer. Now, chuck a top-bearing pattern bit, set its depth to clamped board thickness plus desired dado depth, and rout the dado.

[LarryG]

Something doesn't sound right there...

I think what Mac meant was, "it would eliminate having to make up any type of fixture as you would normally do to cut a dado." Although, technically speaking, the fence that is clamped down, and the two different sized spacers, together comprise a fixture. As do your two 1x4s. Technically speaking.

[DonHo]

Here's a link to a free plan for a router dado jig that will cut exact size dados. For me the best part of this jig is that you don't have to measure any "offset" for the fence, you have an accurate reference point.

http://benchnotes.com/Router%20Dado%...dado_guide.htm

DonHo

[uglystick]

I like the Pat Warner design that Larry shows in this thread. I also read a tip elsewhere to use a piece that has been fully sanded for the width setup for the best dado fit.