I have a dado set that comes with a 1/16" and a 3/32" chipper. These will be perfect for the 5/32" dado I need to cut. Unfortunately, the outer blades are each 1/4", so there's no other combination of blades I could use to get my 5/32" dado.

Noting that the chippers are 4-tooth, is it safe to use just the chippers and not use the outer blades?

I realize that without the bevel, the cuts might not be quite as clean as they are with the outer blades (I'm a bit of a rookie, but I'm pretty darn impressed with my cuts so far), but that's less of a concern than just getting the dados cut.

I realize I could pick up a 5/32" router bit to make the cuts, but that would require making something of a jig to help get nice, straight cuts through the middle of the boards, and doing it on the saw should be much quicker and easier.

  • I think two passes with a standard blade would be much safer. I'm guessing you mean the outer blades of your dado set are each 1/8" - one of those blades should give a nice, flat bottomed cut. Then just move over 1/32" and run another pass. – Mark Apr 11 at 22:19
  • Sample cut on one small piece of scrap to test? – Graphus Apr 12 at 6:41
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    "...but that would require making something of a jig to help get nice, straight cuts through the middle of the boards" Jig? Just run the router along a straightedge.... if you wanna get fancy, arrange two straightedges with a gap that exactly matches the router base. – Graphus Apr 12 at 6:46
  • I've got long, narrow pieces, @Graphus that need several dados spaced along the short dimension. Makes it more difficult to clamp everything down, but your point is very valid, and may well be the way I end up going. – FreeMan Apr 12 at 12:52
  • You can make multiple cuts with regular blade and move the piece between the cuts. As you need only 5/32" this should be doable in 2 passes with thin blade. – jnovacho Apr 12 at 14:37

I have never tested it, but I would think that a chipper, with only two teeth, might be quite risky. In a standard blade the teeth are secured in their path by the blade disc which serves to guide and support the teeth in the desired path. Without the rotating mass of the blade disc, I would worry that it is much easier for something to go wrong to make the rotating blade wobble and grab the wood erratically. This would result in the chipper arm bending causing the width of cut to be expanded, or worse a loss of control of the wood or failure of the blade. I believe there is an important safety reason blades are designed as they are and we don't see even cheap blades designed without a complete blade disc or so few teeth.

  • Very valid points. These are 4-tooth chippers, so 2 of them stacked together would be 8, evenly spaced around the circle, but still, a very valid concern. Thanks for pointing that out. – FreeMan Apr 12 at 12:50
  • My dado stack (Oshlun) has full circle 5 tooth chippers. I wonder if these would fair better? I do agree that the as chippers are supposed to be contained between two regular blades they might pose some safety concerns (on top of the obvious cut quality concern) – Eli Iser Apr 12 at 13:05

Is it safe to use just the chippers in a dado stack?

No. The chippers are designed to do just that — chip out the middle of a groove being cut on either side by both outside blades.

Some dado stacks come with instructions that state not to use the chippers without both blades, example from Freud, sixth bullet point from bottom: "Always use both outside blades of the dado set. Never use the chippers by themselves or with only one outside blade."

It may be the case that all dado stacks are only safe to use this way (and I strongly suspect this is the case) but that the instructions aren't as well written for all sets.... if, for example, your set doesn't explicitly say this.

In case it's not obvious for any future readers, the opposite is not the case — it is perfectly acceptable (and common practice) to run the outside blades by themselves, without any chippers, shims or other spacers in between. See both diagram and chart in this PDF from Diablo1.

The correct way to cut a needed groove using a dado set of any kind that can't cut it in a single operation is to use multiple passes. Generally you'll be able to cut once, then move the fence and run a second pass to get the width required2, but you can cut a channel of any width this way if you just keep going.

Alternatively, just use your router
This is bread and butter stuff for a router, and of course far safer3.

realize I could pick up a 5/32" router bit to make the cuts

Although at first glance it seems very handy4 it's not required to have a router bit that matches your stock thickness, since a smaller bit can always cut a groove wider than itself via multiple passes.

but that would require making something of a jig to help get nice, straight cuts through the middle of the boards

No jig is required for this, at the most basic you just need to run your router along a straightedge.

If added security against wandering is required you can arrange a second straightedge parallel with the first. This doesn't take as long as you'd think, and once you've done it a couple of times it's something you can set up almost on autopilot (since the base itself is used to ensure spacing there's no measuring needed for that part of the setup).

1 Notice that it is implicit in this that both outside blades are fitted for all grooves wider than 1/4".

2 Rather than relying solely on the tape measure built into your saw or measuring manually from the blade to set the fence for the second cut scrap pieces should be run so you can dial it in; this should probably always be done, but it is vital where very tight tolerances are required.

3 Important reminder that dado stacks are considered so dangerous elsewhere in the world that in those markets they're actually banned from being fitted to table saws in commercial workshops. And furthermore, saws are deliberately fitted with short arbours that makes fitting one impossible.

4 While your router bit and stock may be the same size on paper, the reality might be quite different. The bit is likely to be dead on, but the stock could be way off (particularly with plywood, which not only can be over- or undersize, it can even vary in thickness place to place).

  • Seems like the best bet will be to line up all my pieces, clamping them to my work surface and gang-cut the dados with the router. Will have to rummage through my bits to see if I've got one small enough. – FreeMan Apr 12 at 13:54
  • Yes, gang them together. I literally came back to suggest this :-) – Graphus Apr 12 at 13:56
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    BTW because I don't use Imperial fractional measures every day I totally spaced on the tiny size of groove you needed here <doh> Fingers crossed you do have a 1/8" bit. – Graphus Apr 12 at 14:05
  • I've measured the edge of a piece of hardboard I've had sitting in my garage for a while. My calipers gave me 0.155", and 5/32" is the closest fractional size, but slightly over, which should be good for a removable divider. I suppose I should pull the whole thing out to ensure it's actually usable before making any cuts,eh? ;) – FreeMan Apr 12 at 14:15
  • Probably wise! I've had more than one piece of (untempered) hardboard look to be in good condition but be furry on the backside or swollen lower down, hidden by whatever was in front of it. – Graphus Apr 13 at 7:02

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