Shelf Dados on Table Saw Method?

[Jim Becker]

OP, you don't say what material the cabinet wall is made from. If it is plywood, and the face grain runs across the dado, you're likely to get chip-out on the edges of a dado cut with a dado head. A router will not give you that issue.

Tooling matters even with a router... but there are options with a router to help control things in that respect. A dado blade chews wood fast. Some are better designed than others to help with the edges, but even with the best ones there's risk with veneer sheet goods as you state.

[Christopher Giles]

Another important reason to use a router with proper template is the consistent depth of the slot you will get vs. the dado blade. It is very difficult to get a full depth dado across the entire side panel by attempting to press down as you go over the blade. The router does this much more easily, and it is critical to your cabinet going together correctly.

[Edwin Santos]

Another important reason to use a router with proper template is the consistent depth of the slot you will get vs. the dado blade. It is very difficult to get a full depth dado across the entire side panel by attempting to press down as you go over the blade. The router does this much more easily, and it is critical to your cabinet going together correctly.

His cabinet sides are only 13" deep.

[Andy D Jones]

This can be a safe and easy job if you have a miter gauge and like most gauges it has a pair of thru holes to mount a long extension. (eg a 3' 2x4). For each shelf position screw a stop block on this extension to establish the left/right position.

This! Especially if you have more than one cabinet (two sides) with the same shelf height. The tops and bottoms of the sides can be rabbeted with the dado blade the same way. The only limitation to this is the length of the guide bar that rides in the miter gauge slot on the saw table. If it is not long enough to accurately engage the slot, with the workpiece fully in front of the dado blade, you need a longer bar, a different miter gauge with longer bar, or to make a dado sled as mentioned above.

You can sometimes purchase router bits that are the same width as the shelf material is thick, but otherwise you have to make two passes with a smaller bit per slot, even if you double up two cabinet sides at once, I would not do it unless I only had one or two sides to dado.

You will likely need dado shims to accurately set your dado head for the thickness of the shelves (or make two passes with a narrower setup).

Also, I would securely clamp the stop block on the miter gauge fence (extension), instead of screwing it in place. In fact, I just use one of my (smaller) hand screw clamps for both the stop block and the clamp! Hint: always use the rear screw for final tightening a hand screw; it has more leverage than the forward (middle) screw.

Note, if you have a router table extension on your table saw, and a router bit to match the thickness of your shelves, you can use the same technique as the dado head, but with the router in the table instead.

-- Andy - Arlington TX

[Noah Starksen]

Thanks everyone for the replies! Helped me think things through a little more.

To bring a little clarity to some questions asked.

I don’t have a router table, just a handheld.
Unfortunately I did already cut the 2 sides apart. Didn’t think that through.
I currently have 2 sleds, one for each side of the blade. I don’t have a typical crosscut sled that rides both miter slots.
Since the shopsmith has the capability for the table to move independent of the blade, this means I can move it over a little and still be able to use my sled without worrying about the blade hitting it.
The sled is 30” wide, meaning I can easily set up a stop block on it for consistent locations on both sides.

The location of the shelves are near the bottom and top, none being in the middle. The furthest is 8” from the bottom. This makes me think I’ll be fine with just a sled on one side.

My dado blade is a wobble dado. While I know it had its weaknesses, it gives me the ability to dial in the thickness. Just takes trial and error on scrap pieces.

So all of that to say, I’m leaning toward table saw with my sled. I did a run through today to see how it would feel, and all seemed fine. Tested some scrap pieces and chip out wasn’t bad at all. Tbh I can’t even notice it.

[Rick Potter]

A bit off the original question, but I thought this might be interesting.

Making bookshelves with dado's is THE reason I picked up a second RAS. I was doing a lot of shelving for closets in my remodel, and the RAS with a decent dado was the answer.

I picked up a decent Sears saw for $200, and used it for dado's in melamine shelving only, until I finished the remodel. I have some more floor to ceiling bookcases with library ladders to put in a couple rooms, after which I will sell the RAS for close to what I spent on it.

It makes them go soo easy and fast. Just thought I would mention another option. Up to 13" wide shelves on that saw. Could do up to 16" with my 12" DeWalt, but I don't want to use it for that.

[ChrisA Edwards]

Being a ShopSmith owner for 30 years, I would never attempt to do the Dado's on it, at least not on the Mark V, I had, as there's just not enough support from the table or fence.

Even with a SawStop, with good infeed and outfeed support, I still do most of these types of operations with a hand held router with a guide. I have two router tables and neither of these would provide anywhere near the support my table saw does, or the fence capacity needed, which is why I use the handheld router with a guide.

Build yourself an exact width guide and these operations will take minutes and be accurate with either through or stopped Dado's.

[Noah Starksen]

Being a ShopSmith owner for 30 years, I would never attempt to do the Dado's on it, at least not on the Mark V, I had, as there's just not enough support from the table or fence.

Can you explain more why you think this? This size is almost completely supports by the table. I’m also using the official shopsmith sled, and the entire bird fits within that sled. So I’m not understanding why you don’t think there’s enough support.

Unless maybe you have one of the old models with small tables. I have the mark V 520, which has the main table plus 3 extensions that can be located wherever you desire (left, right, infeed, outfeed).

[ChrisA Edwards]

Yes mine was an older one, but my process still holds true with my Sawstop.

[glenn bradley]

Lots of good info here. I too would avoid the Shopsmith for this operation. Maybe there is a way to run a large sled on the Shopsmith that would give adequate support. The fundamental problem to me is that dados are captured cuts. Any deviation in the feed path as you are passing through the cut can cause a good kickback. Likewise, not having your material clamped or strong armed to the sled during the operation is not a good idea. I think you have picked up on the basic safety recommendation that the rip fence is not for things that are wider than they are long. Your router or a radial arm saw solve all these issues. I have something like Von Bickley showed but, even a simpler one-off guide will do.

Dado Jig Refresh (10).jpg

[Noah Starksen]

I’m still not fully seeing the lack of support fears. This is the sled I own. https://www.shopsmith.com/ownersite/...idingtable.htm

The sled is 15x31, all on one side of the blade. So the entire piece supported by the sled.

[Dan Hahr]

Aside from safety, the biggest issue for me is getting the dado equally deep across the width. Probably not such an issue with 13 inches, but either way, you need to make sure the face getting cut stays in constant contact with the saw or router plate the entire time. With a dado sled, and typical plywood, this means heavy pressure on the top of the cut. With a router, it means making sure the plywood is not bowed downwards at all causing the plate to bridge the cut.

Dan

[Carroll Courtney]

You can use it safely and accurately,using shims you can match the thickness of the plywood

[Scott Bernstein]

I have done it both ways. Both ways (table saw with dado blade or router) can be done successfully and safely. Both ways can also be done awkwardly and without a high degree of safety. As for tearout, this is also a concern for both methods. Not all straight-cutting router bits are the same and not all dado blades are the same when it comes to tearout. A simple piece of painter's tape over the planned dado can help reduce tearout with either method. Personally, I prefer the table saw. I have an Incra miter sled which has enough capacity to cross-cut pieces 24" wide and a very long fence...I have cut pieces 6 feet long or more. This is more than enough cross-cut capacity for just about anything I'm likely to build. I also use a spacer block on my table saw fence as a reference, so that the piece does not actually touch the fence during the cut. If I am doing several cabinets needing shelves with the same spacing I can set up the table saw and cut all the dados very, very quickly. Then I adjust the fence for the next shelf and repeat. Once everything is set up it goes very quickly and is very accurate. Quicker than a handheld router, for me, even cutting opposite sides at the same time. And obviously there is more ability to set the dado width more precisely with a dado blade set than with router bits. But again, you can have success using either method - I suggest try both techniques at least once and see which one works best for your workflow.

[Rick Potter]

Noah,

If I am correct about your sled, it is cut by the blade for zero clearance on one side, and does not bridge the blade.

My recommendation would be to set your dado set up for the cut, then adjust the location of the left blade on your set to match the already cut edge on your sled. It's a SS and should be easy to do. Then tack a quarter inch thick ply or whatever to the top of your sled, overhanging the cut edge by a foot or so. Take a foot long piece of plywood the thickness of your sled base and tack it on the far side of the dado set for support on that side. Also attach it to the fence on your sled, so it will stay together when you make the first cut on your practice piece. I would make an additional fence to screw on to the face of your fence, as well as the addition. Remove it later, and your fence should be ok.

You now have a sled that supports both sides of the cut, and the plywood you tacked on will be cut the width of the dado, giving you a zero clearance top for the sled. The new fence face, when cut , will also give you a visible reference to exactly where the dado will be.

For extra safety, I strongly recommend you make the 1/4" plywood piece a bit deeper that the shelf is wide (15" or so). This allows you to attach a rear fence to it which will hold the two pieces together much better. Any 1x3 will do. The dado is only going to cut it less than 1/2" deep, so it will be plenty strong.

If you do it this way you will not ruin your sled for future use. Remember, the only thing holding it together is the fence, so make sure you sturdy it up some.

Hope this helps. Heck, I hope it makes sense.