What Festool Domino Tenon Size to Use? How to Choose?

If you just bought a domino joiner, you might be asking yourself which domino tenon size to use for your next woodworking project. Getting it right is key.

festool domino joiner
“Maker Ed at Tam High” by fabola is licensed under CC BY-SA 2.0

Here’s the quick answer: you should use the biggest tenon you can without compromising the project’s integrity, which usually means using a domino that is about 1/3 the thickness of the material. You should also consider the type of wood you are joining. On the other hand, if you are looking for alignment only, smaller tenons are sufficient.

Let’s discuss the issue in the following article.

Festool Domino Size Chart

First of all, let’s have a look at the Domino tenon sizes available. As you probably know, Festool manufactures 2 domino joiner models: the DF 500 and the XL DF 700. The following tenon sizes are available for the DF 500:

  • 4 x 17 x 20 mm;
  • 5 x 19 x 30 mm;
  • 6 x 20 x 40 mm;
  • 8 x 22 x 40 mm;
  • 8 x 22 x 50 mm;
  • 10 x 24 x 50 mm.

You can get this systainer that includes 1060 tenons of all the different sizes, and 5 cutters (1 for each different tenon size). All of them are organized conveniently in storage bins with dividers.

While the XL DF 700 can cut mortises for these tenon sizes:

  • 8 x 22 x 80 mm;
  • 8 x 22 x 100 mm;
  • 10 x 24 x 80 mm;
  • 10 x 26 x 100 mm;
  • 12 x 26 x 100 mm;
  • 12 x 26 x 140 mm;
  • 14 x 28 x 100 mm;
  • 14 x 28 x 140 mm.

Here you have a systainer with 8-10mm tenons and the corresponding cutters; for the bigger sizes, 12 and 14mm, here‘s another T-loc systainer for them.

As you can see, each tool requires specific tenon sizes. The first number is the tenon’s thickness, the second is the width, the third is the length.

What about the materials? They are made of beech hardwood, which is a warranty of quality and durability. Apart from the 4 mm tenon, the others are also available in sipo mahogany wood. It’s African, rot-resistant wood, which makes them perfect for outdoor projects.

What about the cutters? each tool can be equipped with different sized bits:

  • For the DF 500, the following cutting diameters are available: 4-5-6-8-10 mm;
  • The XL DF 700 uses these cutters: 8-10-12-14 mm.

The 8 and 10 mm cutters are not interchangeable, each tool needs its own.

What Domino Size to Choose for Your Project?

So after introducing the different tenon sizes available, it’s time to decide what size of Festool Domino to use.

As I said before, a good rule of thumb is using a tenon which is about one-third the thickness of the boards you want to join. It’s just a general indication, a little more or less will be fine most of the time.

The final decision needs to take into consideration the application in hand. Here are a couple of points to keep in mind:

  • Are you joining hardwood, softwood, or plywood? Generally speaking, you want a joint which strength matches the resistance of the wood around it. That’s why the 1/3 rule works well with hardwood. For softwood and plywood, a tenon too big might compromise the project’s integrity.
  • Are you looking for strength in your joint? Are you using tenons just for alignment purposes? If the latter is your case, you can use smaller dominoes. Even biscuits would be fine (if you happen to own a biscuit joiner).

Getting the size right is very straightforward. On the other hand, deciding how many tenons to use and how to place them might be trickier. Here you have some notions to use as a starting point:

  • If you are joining large boards, for example to create a tabletop, place a domino joint every 6 to 8 inches;
  • You might think that placing two tenons inside one mortise makes for a stronger joint. On the contrary, you risk reducing the cross-section too much, weakening the entire connection. It’s better to create multiple, closer-together slots. Leave a minimum of two times the domino’s thickness between slots. If you want to stack them in the shorter direction, leave a quantity of material at least equal to the tenon’s thickness.

There are different approaches, all of them have pros and cons. The best thing here is using a trial and error method. Start with simple projects, learn from your mistakes and carry on. You’ll make your own rules in no time.

Frequently Asked Questions

festool domino
“My new screen door. #festool #tools #domino500 #workshop” by Blind Robert is licensed under CC BY 2.0

Now let’s answer some of the most common questions asked about domino tenons’ right size, the Festool tool, and the Dominoes in general.

What Festool Domino Size is Right for 3/4 Hardwood?

With this type of material, there’s no risk of the joint being stronger than the material. So you can apply the 1/3 rule without trouble. For 3/4 hardwood, which amounts to about 19 mm, a 6 mm tenon is ideal. You can also use an 8 mm tenon if the joint is large, for example if you are creating a countertop.

What Festool Domino Size to Use for 3/4 Plywood?

In this case, it’s better to stand on the lower end. Using a 6mm or an 8mm thick tenon might make the plywood split. The same goes with softwood. For 3/4 plywood, you should use a 5mm domino tenon.

What Size Domino to Use for 1/2 Plywood?

1/2 Plywood corresponds to a little less than 13 mm. You should use the smallest tenon available, which is 4mm thick.

What’s Festool Domino Minimum Thickness?

For the Festool DF 500, the minimum thickness available is 4mm, which is ideal for smaller projects. The minimum thickness of the XL DF 700 tenons is 8mm. That makes the Festool 700 more suitable for large projects, for bigger scale productions.

What’s Festool Domino Tenon Width?

The domino tenon width changes between the different tenons. These widths are available: 17-19-20-22-24 mm for the DF 500 tenons, 22-24-26-28mm for the XL DF 700 tenons. As you can see, the range of choices is limited. That is often treated as a drawback of the domino system since it might reduce the final joint strength. The most obvious solution is placing 2 joints side by side. As I mentioned before, leave about 2 times the thickness of the tenon between the cuts.

How Deep Can A Festool Domino Joiner Cut?

The maximum depth to which a Festool domino joiner can cut differs between models. The DF 500 can cut at 12-15-20-25-28mm; the XL DF 700 can cut holes from 15 to 70 mm deep, at 5 mm steps. Both tools have convenient depth adjusting mechanisms. Many depth levels are available for both tools, which makes it possible to offset the tenon if necessary.

Generally speaking, you want to use a cutter that matches the tenon’s thickness. Unless the workpiece requires it, it’s better to center the domino between the slot to get a consistent joint.

Are Dominos Better Than Biscuits? Which is Stronger?

It’s difficult to compare domino tenons to the biscuits which are used with biscuit joiners. They are made for different applications. Biscuits are ideal for small projects, while dominos work well in many applications, such as cabinetry and furniture-making. Check this article if you wanna learn more about domino joiners when compared to biscuit joiners.

One thing is certain: dominos are way stronger than biscuits. Domino tenons are way thicker, plus they are made of solid hardwood. For comparison, biscuits are made of compressed wood.

Are Dominos Better Than Dowels?

If you need a strong joint, both dominos and dowels are solid choices. The only point that could make you choose one over the other is torque strength, which is the resistance to torsion. In this matter, dominos are way better than dowels, due to their larger, oval-shaped cross section. In all other respects, dominos are very similar to dowels.

Final Thoughts

At this point, you should have a much clearer idea about the domino tenon sizes available on the market, and how to choose the appropriate one for your workpiece. In summary, these are the key points:

  • Domino tenon sizes differ between DF 500 and XL DF 700. Each tool require specific cutters;
  • Typically, the tenon should be around 1/3 of the board thickness. A 6mm tenon is commonly used for 3/4 hardwood. When using plywood and softwood, keep to the lower side: use a 5mm thick tenon;
  • Don’t stack multiple tenons inside a single mortise. It’s better to cut multiple slots at an appropriate distance so that you don’t compromise the wood’s integrity;
  • Dominos are stronger than biscuits, while they beat dowel only for torsion resistance.

Well, that’s it for this topic. Time to get to the workshop now! 😉

1 thought on “What Festool Domino Tenon Size to Use? How to Choose?”

  1. Steve Lee

    Thanks for the helpful post, but take a look at a Biscuit and a Domino and you will see that they are both made of Beech. the Biscuits are compressed to allow them to swell minutely when wetted by the applied glue line. They are cut diagonally to the grain which makes them very difficult to break.
    The Domino by design is generally thicker, except in it’s smallest form of course.


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