Setting Up A Dado

[Ken Krawford]

I'm making an extension table for my table saw. I have an 8" Freud Super dado set but can't seem to find the right combination of chippers/shims to cut a .755" wide dado to extend the miter slot. Other than a million trial and error cuts, does anyone have a better way to set this up?

[Peter Aeschliman]

I usually do the trial and error method, though it doesn't take a million test cuts. :)

If you get yourself a set of digital calipers, it would probably help... for example, you could stack the set at .75 per the instructions that came with the dado set, and then measure the shims until you come up with a combo that gives you the extra .05". Should save some setup time.

[Steve Wurster]

Do you have to make the cuts in one pass? You could always go with a smaller dado setup and just make multiple passes. I think I did that when I made my table (although I don't remember).

[ian maybury]

I'm relatively new to dado cutters, but Forrest do magnetic shim washers for their own sets for fine width adjustments. They would likely work on a Freud if you can get them with the correct hole size which also seems likely. DIY shims may an option at your own risk too. They need to be flat, able to ahndle the clamping load when it's done up and transmit the torque.

The Forrest dials in pretty easily and cuts very close to the set (measured) width, but that would likely be influenced by any possibility of shake, looseness in fit of the bore or wobble in your saw arbour...

[George Bokros]

When I made my extension table I used a router to make the miter slots and I believe I just used a 3/4" bit.

[Peter Aeschliman]

Ken, I blew right past the project you're working on... For an extension table, you don't need the slots to perfectly match the table saw table. Just make them bigger than the slots in the cast iron table and you will be just fine. When your miter gauge reaches the point where it would otherwise make contact with your extension table, the cut is essentially complete and there is still plenty of contact with between the miter gauge and the cast iron slot to maintain accuracy.

The point is to just keep the extension table from interfering.

If the slots in your extension table are 1/4" wider than the slots in your TS table, you will be just fine.

[Jim Dwight]

I usually set it up how I think will work (in this case enough chippers to get to .75 plus a .005 shim) and make a test cut. That is often slightly off so then I change the shim and try again. I don't do dados with the TS a whole lot because of the setup. If I am just doing one, I use a router or make multiple passes with the blade on the TS.

[Matt Day]

I make mine oversized. Make sure to account for the "T" part of the miter slot if you have it.

To answer your question the shims should get you there.

[Ken Krawford]

Peter, you make a very important point about the cut being finished by the time the miter gauge reaches the extension. Maybe I'll just rough it in with my router. I also use a crosscut sled but the same principles apply.

Thanks for all the other input.


Ken, I blew right past the project you're working on... For an extension table, you don't need the slots to perfectly match the table saw table. Just make them bigger than the slots in the cast iron table and you will be just fine. When your miter gauge reaches the point where it would otherwise make contact with your extension table, the cut is essentially complete and there is still plenty of contact with between the miter gauge and the cast iron slot to maintain accuracy.

The point is to just keep the extension table from interfering.

If the slots in your extension table are 1/4" wider than the slots in your TS table, you will be just fine.

[Brian Henderson]

Years ago, I took my dado set and a long piece of MDF and cut every possible combination of chippers and shims, plus what combination I put together to make the cut. Now I can just take whatever board I want to make a dado for (or calipers in this case) and know exactly what to put together. Take the board, slip it into the slots until you find one that fits and Bob's your uncle.

[Mike Goetzke]

Ken, I blew right past the project you're working on... For an extension table, you don't need the slots to perfectly match the table saw table. Just make them bigger than the slots in the cast iron table and you will be just fine. When your miter gauge reaches the point where it would otherwise make contact with your extension table, the cut is essentially complete and there is still plenty of contact with between the miter gauge and the cast iron slot to maintain accuracy.

The point is to just keep the extension table from interfering.

If the slots in your extension table are 1/4" wider than the slots in your TS table, you will be just fine.


Peter, you make a very important point about the cut being finished by the time the miter gauge reaches the extension. Maybe I'll just rough it in with my router. I also use a crosscut sled but the same principles apply.

Thanks for all the other input.

...maybe make them a little deeper than the cast table also.

Mike

[Kent A Bathurst]

Peter, you make a very important point about the cut being finished by the time the miter gauge reaches the extension. Maybe I'll just rough it in with my router. I also use a crosscut sled but the same principles apply.

Thanks for all the other input.

Yeah - - mine are about 1" wide x 7/16" deep. You just need a runaway truck lane past the edge of the freeway...........

[Rod Sheridan]

I use a set of digital calipers and stack the set off the saw.

I set it off the saw, make a test cut and then add exactly how many shims I need.

Regards, Rod.

[glenn bradley]

Like Steve, I always make my stack thin and do multiple passes. I have a DRO on the tablesaw so this is just a method I lean toward since it is quick and simple to do.

[Kent A Bathurst]

I use a set of digital calipers and stack the set off the saw.

I set it off the saw, make a test cut and then add exactly how many shims I need.

Regards, Rod.

Me too. And then....I keep my shims in a envelope - some of the slip-on plastic kind and a set of magnetic.

After I get it set up, on the envelope I write down the blades and shims I used for that width.