How the Domino works

This is a pretty good video showing how the Domino works. I am not impressed with the technique.
For certain I see two problems.
1. He is using precise fitting mortises and claims a perfect fit. What I consider a perfect fit and what he may may consider a perfect bit are apparently not the same.
If you go to precisely 5:41 on the video and see him using a rubber mallet to close the joint look closely at the left upper stile. The end of the stile protrudes past the edge of the rail. There is no way to fix that short of cutting the ends of the assembly after glue up. I use a precise fit mortise on one piece and an elongated mortise on the mating piece so that I can tweak the fit to be perfect.

https://www.youtube.com/watch?v=xCyyy5Jtf3E

2. He uses the bottom of the Domino mortiser as the reference. This can introduce all kinds of errors. The best method is to always use the fence as your reference surface.
Using the bottom of the Domino will cause misplaced mortises if any of the following conditions exist. And who has never had any of these conditions?
A. The work surface or the work is not perfectly flat. If the work and the bottom of the mortiser are not on the same plane the mortise will either be too high, too low, or at an angle. If the work has a slight bow the mortiser will cut into the surface of the work at an angle, not a perfect 90 degree angle.
B. Debris under the work piece or the mortiser can throw alignment off. Is there saw dust in your shop?
When you use the fence, you can see the top of the work and if it has any dust on it. You cannot if the debris is under the work. The flat fence on top of the work always registers the tool to the work not the work surface. On thin pieces of wood hang the edge or end past the end of the work surface so that the mortiser does not register against the work surface. Even on longer bowed boards if the fence can rest flat on the end or edge most of the bow is taken out of the equation.
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On 9/30/2016 5:52 PM, Leon wrote:
And one more example of the indexing pins not creating a perfect fit. Much easier to see.
Look at 15:07

https://www.youtube.com/watch?v
ŒbWvbuL_u8
Ideally the indexing pins should make registration perfect. In my experience and in the examples the pins are not perfectly the same distance from each end of the bits travel path.
With time the travel of the bit may vary a touch in one direction or the other. Andy deviation from perfectly centered with the indexing pins doubles the error for mating pieces.
The Festool factory reps brought this to my attention 8 years ago and suggested the elongated mortise foe the mating piece.
Can the pins be adjusted on the big Domino? Probably, and one can be adjusted on the smaller Domino but it is only a matter of time before something is not perfect again and you have to make more adjustments.
I elected early on to not spend time looking for perfectly precise alignment between the pins as the easier way is to use an elongated mortise on one side of the joint. 14,000 + mortises later this still method still works great.
Now you can use the indexing pins with precise fit mortises if you do not mind coming back after flue up and cutting or sanding the proud surface. I prefer not.
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Hi Leon, I'm not trying to be contradictory but I like using the bottom of the Domin o whenever it's convenient (depending on the material thickness and the cut ter size) for joining. Sometimes I have affixed various thickness shims to offset the bottom for setting mortises into materials. I clamp my work pi eces to the MFT and am conscious about keeping the area free of debris that could shift the Domino. I do use the fence - as you prefer - but I've found I have better control r egistering the joints off the bottom.
With regard to "precise fit mortises" I cut them on one face and then I cut one on the indexing edge of the mating face. The rest of the mortises are elongated. I've rarely had any misalignment but when it has occurred I just trim off a small amount on the edge of the tenon and the fit is then dead on.
Do you often use one or two dominos just to see how a dry assembly would wo rk out? I keep a small "supply" of lightly sanded dominos for dry assembly because it is a lot easier to take apart the pieces when they are not as s nug. Sometimes when I think about it in advance I'll toast a few dominos in the oven to make them easier to remove as well.
Take care and keep on "Festooling" Marc (who is happy he owns and uses all o f his Festools)
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On 10/11/2016 8:37 PM, marc rosen wrote:

Understood and certainly there are often situations when you need more range than the fence will allow. I too have used the base as the registration. It is just that you have to keep in mind any debris that may be under the board/work and or the Domino mortiser base. AND if the work is bowed it must be clamped flat.

I'll keep that in mind, making the tenon narrower however that pretty much is the same as elongating the mortise. ;~)

No, actually I can't recall dry fitting any joints on a project where Domino's are being used. Using the method of exact fit mated with elongated takes the surprise out of the equation.
I do recall however placing 2, 5mm domino tenons on each side of 4 shelves to index into the back, front, and sides of my old bedroom tower project. Basically I had 32 Domino tenons registering the fit of 8 different planes/panels. I was anal when assembling the multi rail and panel outer 4 sides of the towers so that the shelves tenons would align properly. I actually thinned some of the trial domono's for a test fit on that. I did no such test on the second tower. AND I had additional domino's along the length of the outer panels to join the outer corners. I hope to never glue up something that complex again. IIRC that was probably 70+ Dominos in one glue up.
That was on this project.
https://www.flickr.com/photos/lcb11211/4243010610/in/dateposted-public/
https://www.flickr.com/photos/lcb11211/4242237877/in/dateposted-public/

LOL, all of your Festools? So do I. I have heard stories about guys that buy Festool tools and are afraid to use them.... Go figure.
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On 9/30/2016 6:52 PM, Leon wrote:

You'll all probably tell me it's perfectly safe, but I don't think I'd be comfortable pushing such small stock through the router table with just my fingers. Maybe that's my own inexperience, and maybe it's also my wish to continue my 50+ years of playing piano, but I think I'd need to find another way. I did make a set of panel doors a few years ago, with 1x3 rails and stiles. I can't remember how I pushed the stock through, but I doubt it was like that.
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On 10/12/2016 2:32 PM, Greg Guarino wrote:

You can see it at about 4:45 in the video. Note how for a second you can even see his fingers shake a bit from the strain.
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On 10/12/2016 1:32 PM, Greg Guarino wrote:

His technique is correct BUT he should be using a bush block/pad. That stock is relatively narrow and if it were to shatter for what ever reason his fingers would pay the price.
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Pretty sure the easiest and safest way to make a Domino narrower is to run it against a file or piece of coarse sandpaper. Holding it with your hands . Not much danger. Pretty sure I could take off 1/16" or 1/8" off the edg e of a Domino with my file in less than a minute. Easy.
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On 10/12/2016 4:06 PM, snipped-for-privacy@yahoo.com wrote:

A "domino" is, for all practical purposes, a loose tenon.
Only in the context of tweaking the width of a loose tenon, I'll do your above when I only have a few to do.
If I have a projects worth, I'll use the combo belt/disc sander. Safe, quick, easy.
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On 10/13/2016 9:51 AM, Swingman wrote:

A disk sander is pretty effective for me.
On another note, if you will recall when putting in exposed Domino tenons, on the corners of the rabbited drawers, the outer piece of wood between the tenon and the end of the side of the drawer is often broken and or has chip out. That has to be puttied in.
This time around and after millions of tenons used this way, ;~), I finally figured out to sand a wedge shape on the end of the tenon before hammering it in the mortise. Out of 144 tenons I did this way on Tuesday I only had 4 that gave me problems. :~)
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