Can't get a flat dado

[Alex Berkovsky]

I just finished routing a 7" wide dado and got an uneven face on the bottom. I used a 3/4" straight bit and made several passes. I am sure it is my technique that's at fault - am I applying eneven pressure with each pass?

[Doug Shepard]

How much is it off? If there's an actual tilt to it that's visible to the naked eye, I'd suspect your collet might be slipping. Dust buildup on the work surface or even the turret stops can account for some minor differences but those little variations will usually pop right out with a sharp chisel. Is your dado actually 7" wide? Or did you mean 7" long? If 7" wide, then I'd have to ask what sort of base plate you're using to straddle the cavity and whether it might not be stiff enough.

[Richard Wolf]

Bring it to my shop tomorrow when you come and we can fix it on the table saw.

Richard

[Alex Berkovsky]

Bring it to my shop tomorrow when you come and we can fix it on the table saw.Richard,
I'll bring it with me tomorrow.


... If 7" wide, then I'd have to ask what sort of base plate you're using to straddle the cavity and whether it might not be stiff enough.Doug,
The dado is 7" wide - the width of the router base. I am making a mortising jig (http://a4.cpimg.com/image/A6/15/54727334-199b-018B0200-.jpg) and the router will slide in this 1/4" deep dado. I was routing this dado on a router table.