I’d take a wild guess that the base of the machine was coming in contact with a bench top and as a result the mortise got cut slightly higher than it should have. Don’t ask me how I know about that 😂
If not then maybe you were tilting the machine ever so slightly. It all falls under the “technique” Hard to say exactly what the issue might be. Could you post a few pics of the joints you’re getting.

How long have you been using the domino machine?

Edit:if you’re fairly new to the domino it takes a bit of use to get the feel of something not being quite right. If a quick pass of p80 on an orbital would clean it up I wouldn’t worry too much. Double check your fence adjustments for tightness

 

I’d take a wild guess that the base of the machine was coming in contact with a bench top and as a result the mortise got cut slightly higher than it should have. Don’t ask me how I know about that 😂
If not then maybe you were tilting the machine ever so slightly. It all falls under the “technique

How long have you been using the domino machine?

I've been using it for a couple of years so not a total amateur at the device but obviously I'm not an expert either. @StevoWevo are you getting perfect alignment every time?

 

Not 10000% and I wouldn’t claim to be an expert either. I’ve had plenty of cuss moments 😮😄
Sometimes I get a bit of twist in a piece if I don’t get it to a glued joint soon after milling. I dont have a moisture meter at the moment and I am sure some of the stock I’m getting is on the high side. Couple that with being in a hurry and not going through a mill, rest, check and remill cycle invites occasional stock prep issues. So long story short check your edges for perfect square when it’s critical. On something that’s getting painted I don’t worry quite as much. In any case I almost always expect to be sanding to some degree after a solid wood glue up

 

I find that having the machine sitting flat on a dead flat surface with all the parts show-face down on the same flat surface is the best reference to get matching mortises in all the parts. If you depend on the fence on the Domino a slight tilt of the machine will alter the entry point of the mortise ever so slightly causing misalignment. By having everything on a flat reference surface you just have to hold things down on the surface (machine and parts) versus having to align the machine to the face in mid-air. Anymore, I try to do as much cutting as I can without using the fence that came with the machine.

The other thing I to think about is that there needs to be some space for glue between the mortise and the floating tenon. So if you are just clamping things without cauls or something to hold things in alignment the small differential left for glue can cause some minor misalignment. Usually the adjustment after the fact is some sanding to level things out as this alignment error is pretty small, not sure how much misalignment you are seeing.

 

I find that having the machine sitting flat on a dead flat surface with all the parts show-face down on the same flat surface is the best reference to get matching mortises in all the parts. I

^^^^^^^^What he said.

 

I believe @MFled is correct, at least that was my experience. Seneca came out with their Domiplates for a reason.

So no, I was never happy with the alignment. I tried everything and paid attention to everything I could like holding it different ways, being aware of the plate contacting bench, massive down pressure in the fence etc. but became frustrated - was it me or the tool? I ended up concluding it was the tool.

I did get good results, but I could never get consistent results. Slightly misaligned joints can be dealt with but my conclusion - the Domino is good for joinery, not as good for alignment - in my hands . I see all these other people using them and getting perfectly flush joints and got tired of wondering why I couldn’t. I thought the Domino would be a game changer and it was not for me.

Ironically, I sold it on Ebay during the pandemic for $1100. I paid $850 for it 2 years before.

I do all my face frames with pocket screws now.

 

I do all my face frames with pocket screws now.

You bought one just for face frames?

 

I never had problems with the Domino, Keeping the fence flat in mid air or on the table.

 

I've found several good tips on using the Domino from Sedge at Festool (and sedgetool youtube channel) - especially those on the best positioning and plunging of the tool. I'm not perfect with it but getting better

 

Domino is a pretty easy tool.Understanding it’s features makes for the best experience.

 

I get the best alignment with my domino by pushing at the cord. It was suggested to me by a Festool rep. I don’t know why it works better but it does.
Good Luck

 

Keeping the plate flat to the work results in zero problems.

 

Domino is a pretty easy tool.Understanding it’s features makes for the best experience.

Keeping the plate flat to the work results in zero problems.

Obviously not. Yes it's an easy tool, but it has nothing to do with understanding the features.

Seneca makes those Domiplates for a reason. I always felt using the fence was not as consistent.
I got the best results registering off the table as other's suggested, also pushing at the cord end. But you have to remember to put face down and you have to wrap the alignment mark.

I do all my face frames with pocket screws now.
You bought one just for face frames?

No I wouldn't spend $$$ just for that. I got one for doing mortises I build a lot of furniture but Ia quickly found out you really need an XL for a lot of them. No way I'm spending THAT kind of money!!

 

It’s going to depend on how you look at it. I completely understood the Domino. So I had no issues with it.

One has to keep in mind how much I used it..

 

Glad you mastered it. I’m not the only one who had the issue. But then again, I’m a hobbyist, not a professional. 🤣🤣🤣

 

No such thing as a professional remember, just payed skilled wood-woodworkers..

 

Haven't read all the comments and not sure whether this is applicable... but, have you calibrated your cursor.

I couldn't believe a treasure like a Domino could have issue, but I had alignment issues... I've written an article at another site that I'm not permitted to link to here, however, check out this video... may be your salvation.

 

I thought the op’s miss alinement was up and down faces. Never knew there could be left or right with ends off. I make my own dominos since I don’t use it very often or need that many so left or right isn’t a problem.
I still stand by my suggestion pushing the tool from the end has been more accurate for me.
Good Luck

 

No disrespect meant, however, if you use the wide pockets U'k'c, alignment is no issue... but if you choose the tight setting (for the first pocket), tolerances of branded dominos could snafu you, with a mis-alligned cursor. This is not just a suggestion... it is fact.

You are talking to some bunny that sleeps with his Domino... OK, I lie... I sleep with my Capex next to my Carvex, to the dulcet humming of my VAC-$Y$.

 

I think the issue is alignment of the surfaces.

The Domiplate was created for plywood but it solves the alignment issues involved with registering off the fence. I've never used one but turning the Domino upside down probably takes some getting used to.

Domiplate™ for 1/2" and 3/4" nominal ply

The Seneca Woodworking Domiplate is a fixed fence solution designed for the Festool Domino DF 500. It allows quick centering on 1/2" and 3/4" plywood.

www.senecawoodworking.com

 

Another option for narrow pieces is the Veritas Festool Domino Joinery table. It's not inexpensive but is very effective on the narrow pieces such as face frames. Here's a link to Fine Woodworking's review: Tested: Veritas Domino Joinery Table - FineWoodworking

 

For me, there was definitely a learning curve. The preciseness of it creates problems with even the slightest deviation causing misalignment, especially when you're doing a lot of mortises.

Other than the what were mentioned above, I would make sure the fence is not slipping due to not being fully tighten; I know some were having this issue with their DF 500s. Many vids on fix online...you can re-adjust lever or replace it.

 

Mine was slipping down, I look at it and blamed my sloppy self. After a few test I realized that I was not able to tighten it enough. Total waste of time emailing Festool Customer Service. Might as well ask your dog.
I found this video on a 13 dollar improvement part ( ratcheting lever ) as it looks like JR did above. You can also just loose the screw and shift the lever to the left to give yourself more range to tighten.