Domino joinery, what am I doing wrong?

[Brian Runau]

Building a coffee table and assembling the pieces for the skirt pictured here. I always use painters tape so I can see my marks for my line up and I make oversize mortises in one side of the joinery, the longer stretchers here. I even mark the tape with a felt pin 'X' so I know where the mortise is going. Review my set up before proceeding. In this example I had my fence at 90 degrees. Using a 5mm mortise bit.

I referenced the long stretcher off the outside face and put the mortises in the ends of those two boards. So the center line is down from the bottom of the fence to the center line of the bit.

The shorter stretchers overlap and hide the end grain on the longer stretchers, so the mortise goes on the inside of the board. the end of this shorter board should line up with the outside face of the longer board. I clamp the work to my table. The shorter end pieces I held the Domino vertically referencing off the end of the board with the bottom of my fence and put the mortise in the inside face. The end of this shorter board should be the same reference point as the face of the longer stretcher.

My problem...The end shorter boards hung over the longer boards by @ 1/32" when dry assembled. I don't understand because i think I was referencing off the same point and the depth of the mortise should have been the same allowing the joint to be flush, but it wasn't. I fixed it by making my mortise int he shorter boards a little more shallow and it came out fine, but....

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[Cameron Wood]

How thick is the stock? The short pieces must have been overhanging the table to allow for the almost 4" Domino fence, correct?
Don't understand the last line about making the mortises more shallow.

[Brian Runau]

Happens to be 3/4" stock, but I don't think it matters how thick the stock is since I am referencing off the bottom of the fence and the same reference face/plane on the work. This is a piece of scrap to show orientation of the tool. Brian

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[Cameron Wood]

Just trying to get the scale with the question of stock thickness.

I have a biscuit joiner that never worked well until I finally figured out that the fence height was slipping & the knob needed to be tightened with channellocks.

I know the Domino fence lock is different, but something to check. Another possibility is a slight rocking of the tool during one of the cuts.

Maybe try it again on the scrap.

[Andrew Hughes]

My suggestion is to push to tool further back near or at the cord. That’s what was recommended to me by a Festool rep.
I get better a surface alignment. Using his suggestion
Good Luck

[Ralph Okonieski]

Make sure the fence is not slipping or moved and follow Andrew’s suggested on where to hold. Make sure to apply firm pressure to the domino downward and forward before making the cut.

[Jim Becker]

Also be sure that the material you are mortising is up off the table enough that the Domino machine isn't using the table as its reference rather than the top of your material. That's a very common cause of "Wednesday, Thursday, Friday" exclamations when something is slightly off the correct position.

[John Kananis]

Did you accidentally flip the long pieces around the wrong way?

Edit: The mortise looks pretty close to center so if you inadvertently flipped the insides to become the outside, there will be an offset and you're not "perfectly" centered.

[Jamie Buxton]

Right now, you're depending on getting the fence set firmly and accurately against the end of the board. If you don't get it done right, that might explain your results. Festool actually includes a device in the box which helps ensure you get the tool aligned. It looks like a plastic angle iron with a couple of thumb screws in it.

[Mike Congiusti]

Brian,

I had the same issue when I first started using the Domino. It's has been already mentioned but again, make sure the work piece is hanging over the table and the fence is not hitting the table. What helpped me the most was using the vertical support that came with the unit. It kept it from rocking and kept the machine 90 degrees to the face. I just completed a series of domino's that had to be 3/8" from the edge. The setting 32 got me real close. Also said, make sure you are holding the unit near where it plugs in and go slowly.

I last thing, when you do that vertical cut, I would clamp a scrap piece under it to keep the machine from rocking as you plunge it down. It seems any little movement and you are off by a 1/32.

Good luck.

[Larry Edgerton]

Perhaps slow down on your plunge. The machines have a tendency to move to the right, slow is better. Keep you eye on the mark the whole time you are plunging, so you can correct if it drifts right.

[Brian Runau]

Thanks to everyone. Been using my Domino for a few years now, recurring problem. My workpiece is always clamped down and overhangs the work surface. I do plunge with my hand on the front hold down and the back of the tool. Vertical usage is wonky, but.... when I finish my current project I think I'll play with this tool to try and work out the bugs. Brian

[Michael Burnside]

Happens to be 3/4" stock, but I don't think it matters how thick the stock is since I am referencing off the bottom of the fence and the same reference face/plane on the work. This is a piece of scrap to show orientation of the tool. Brian

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If the fence is square, it's the operator. I don't have alignment problems using the holding technique Andrew outlined. I also never plunge as you've demonstrated in the second picture. It's unnatural and easy to pull the domino towards you. Plus, it's just not very stable. I clamp vertically and place a secondary block behind the reference face. The secondary block prevents tipping the domino forward and makes most domino plunges the same motion.

[mike stenson]

I agree, I only use the domino in a vertical fashion when I've got a fence clamped across the workpiece. But that means I'm registering against the foot, which means I can push into the fence. Same with a biscuit cutter too, to be honest.

[Derek Cohen]

Slow, deliberate plunging. A fast plunge will cause the cutter to move sideways.

On a long board, position #1 on on side and position #2 opposing.

One hand pressing firmly down on the fence handle, and the other pushing from the end of the machine. Be careful not to tip and lose the square position.

This little hack from Sedge helps prevent the fence from moving ...

https://www.youtube.com/watch?v=lyHctMqslxo&ab_channel=sedgetool

Regards from Perth

Derek