Cutting a 7/8" dado - best method

[Dick Snyder]

I am building a drill press table based on one built by Bob Davis. I ordered the hold downs, knobs, and t tracks from Peachtree. To my utter amazement, they got 100% of the order wrong (toggle clamps rather than hold down and today I just realized they gave me the wrong size t track)!! I have already called them to get the hold downs but I don't really want to now wait an additional week while they send me the proper size t track. I am going to go with what they sent me (I still plan to call them so they are aware of my impression on my first order from them).

The t track they sent me is 7/8' wide versus the 3/4" wide I asked for. My table saw dado will do 3/4" and I have a router straight cutting bit that cuts 3/4". I wonder if any of you have a good technique for making two passes with either the router or dado on the table saw to hit 7/8". I am current inclined to do the table saw with two passes and "sneak up" on 7/8" but I thought there might be a better idea out there amongst all of you skilled woodworkers.

TIA.

Dick Snyer

[Leon]

Clamp 2 STRAIGHT boards on both sides of the track in the location that you want. Remove the track. Mount a top bearing flush trim bit in your router and use the 2 boards as your guide.

[TWS]

If you haven't cut your dado yet then set your dado width to something more than 7/16 inch. It has to be greater than half your final width. Let's say 1/2 inch.

Set your fence so that the fence is exactly the proper distance to the side of the blade closest to the fence. This will be one final edge of your dado. Cut the dado. Then move the fence 3/8" (3/8 + 1/2 =

7/8) further from the blade and cut the other side of your dado. For a precise 3/8 shift I usually place a piece that is the exact thickness (two back to back shims can be adjusted to be the exact thickness) against the far side of the fence, clamp my magnetic clamp against that, remove the shims, and move the fence against the magnetic clamp. You can adjust this technique with feeler gauges to get extremely precise cuts.

TWS

[Edwin Pawlowski]

I've done just that. I used a scrap piece first to check the dimension.