# 2" dado on table saw



## RickDel (Dec 17, 2018)

Hello, I'm a beginner level woodworker and I want to make a torsion box out of 4" MDF. I'll be making the lap cuts with an 8" dado blade on the TS. I know making dados and rabbets with a router is normally done with multiple passes, but is that the same with a TS and dado blade? Or do I just cut the entire 2" cut in one pass? Thanks.


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## WhyMe (Feb 15, 2014)

The widest dado I know of for a regular TS is a little over 3/4" so it take multiple passes to do 2". Duh.. I guess you're talking about the depth not width. Yes it's best to make multiple passes, 2" is a lot to cut in one pass. But it will depend on which way you are cutting, along the length or through with board on thin edge.


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## BillWhite (Jul 23, 2007)

I've never seen a dado blade set that will cut a 2" dado in one pass. Multiple passes? Yes.


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## wapakfred (Jul 29, 2011)

I think you're referring to the depth of the cut (that's a question), and if true I just did that last week and cut the entire 2" in one pass. Actually, I think my web was more like 3 1/4" deep…so my cut was likely closer to 1 5/8". I also gang cut the members, clamping them together and cut the short ones at the same time, then the long ones. The loong ones would be tricky on a TS (I used an RAS) but it could be done.


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## RickDel (Dec 17, 2018)

Yes, depth…. Thanks!


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## shampeon (Jun 3, 2012)

You'd need quite a large HP motor to spin and cut a 2" dado to full depth in one path. Certainly not the kind of saw you'd find in a home shop.

When you cut your dado, set up a stop block with an offcut of the 2" wide piece on the inward side, then make the first cut. Then remove the offcut and replace it with another scrap piece the same width as your dado stack (for example, if your dado set is 1/2" wide, a scrap piece 1/2"), and make the second cut. Remove any waste in the middle, and you've got a dado exactly the same width as your cross piece.


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## tvrgeek (Nov 19, 2013)

I would not try and cut more than 3/8 depth at a time.


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## RickDel (Dec 17, 2018)

Thanks guys…. multiple cuts. Got it!


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## Lazyman (Aug 8, 2014)

With MDF, I would do 2 passes. I've done plywood with a single pass at over 2" with no problems. For best results make sure that you attach a backer board to your miter gauge or use a cross cut sled. This will support the cut on the back and prevent tear out. It also makes it easier to set a stop block so you can make multiple identical cuts, since all of the the cuts on parallel boards need to be in the same place.


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## LeeRoyMan (Feb 23, 2019)

> I think you re referring to the depth of the cut (that s a question), and if true I just did that last week and cut the entire 2" in one pass. Actually, I think my web was more like 3 1/4" deep…so my cut was likely closer to 1 5/8". I also gang cut the members, clamping them together and cut the short ones at the same time, then the long ones. The loong ones would be tricky on a TS (I used an RAS) but it could be done.
> 
> 
> 
> ...


I agree with Fred.
I would try the first cut full height and see how it goes. If it's touchy try a couple of passes. It's hard to say when we have no idea what type of saw your using, or your set up of off tables and/or side tables for support.


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## RickDel (Dec 17, 2018)

Thanks guys…. I'm going to do the multiple passes. I have a small portable Bosch 4100. It's really no more work to do multiple passes. I mainly wanted to ask for the knowledge of what more experience guys are doing. Thanks Again.

Question Answered. Thanks


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## therealSteveN (Oct 29, 2016)

I agree with LeeRoy, and Fred. Try full depth. You have an 8" blade, so it would do it, and for a cross lap cut, you are going to limit width to the size of your members on the Torsion box. Most folks use 1/2" or less on the thickness of torsion box material, for weight.

I think you could cut 3/4" stuff as well, maybe just couldn't lift the torsion box once built.

Let us know how you do.


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## wapakfred (Jul 29, 2011)

To be clear: my cuts were in plywood, and I did need a backer board on the exit side. But in terms of power, my RAS is a (true) 1.5 HP saw and it had no problem. But maybe with MDF and a your saw multiple cuts might be best. You could also do it the more conventional way: no lap joints. The cross members side-to-side would be cut to length and then toe nailed with brads and glue to the longer members….that's how David Marks did his IIRC.


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