Rails to Boards - Same Idea - Different "Presets"

Now let's figure out the "fence boards" and their corresponding upper and lower rail mortise locations.

As was the case for the Rails & Posts mortises, start with the part that will have the end grain mortises. In this case that's the "fence board" which is 5/8" thick - or - conveniently - 16mm - which happens to be one of the DOMINO's "Mortise Centered on Stock Thickness" fence presets. So the fence board's mortise centerline is 8mm from the "show face".

Now that we know where the fence board's mortise will be, and knowing we want the fence board's "show face" set back behind the 1/8" roundover on the rail's edges, we need at least a 1/8" set back / reveal. 4mm would do it, but that would have the Fence to Mortise Centerline come out to 12mm. There is a DOMINO Mortise Centered On Stock Thickness preset of "25"mm, half of which, 12.5mm, which is the Fence to Mortise Centerline. So let's go with the "25" preset and get a 4.5mm set back/reveal for the Rail to Fence Board.

With the "front to back" stuff worked out it's time for the "left / right" mortise location. This one does require ONE layout line - the centerline of the fence board's width. It doesn't even have to be EXACTLY in the center or the board - but its location must be the same on both the end of the board and on the corresponding upper and lower rail.

Because this thing will be out in the weather, such as we have in Northern California, the fence boards are wide and it's early summer and the wood is very dry, I want to prevent the fence boards from cupping. THAT means adding a loose tenon on either side of the center mortise. THAT means I need some slop in one half of the mortise and tenon joint. So I need some slop in one of the pair or mortises for each loose tenon. BUT - I don't want water to sit in a mortise that has some slop because then it will rot the wood over time. So, for the "downhill" mortises, I'll leave NO slop, putting the slop only in the "uphill" mortise.

Once again, the DOMINO provides a "preset" for mortise width slop - actually two "slops" - Plus 6mm and Plus 10mm (the second and third postions of the Mortise Width Selector Dial). Let's go with 6mm of slop - 3mm on either side of the tenon's centerline.

Now the only layout lines you need are
- the centerline on each end of each "fence board
- that centerline transfered to either the upper or lower 2x4 rail
- those centerlines on one of the 2x4 rails extended to the other 2x4 rail
Eighteen pencil lines to do 36 mortises

What about laying out where the "outside" "sloppy" mortises will go?

Don't need them. You see, once the center mortise is cut, you can use the DOMINO's left and right "stop pins" to reference a mortise on either side, from either the left or right end of the center mortise you've already cut. The mortise side of both the left and right stop pin is EXACTLY 37mm to the next mortise's centerline.

So for the "sloppy - tight - sloppy" mortises it's
- cut the center mortise
- switch the Mortise Width Selector to postion 2
- register the stop pin in the "nearside" of the center mortise
- cut the "outside" "sloppy" mortise
- repeat on the other side of the center mortise

And for for the "all tight" mortises it's
- cut the center mortise
- register the stop pin in the "nearside" of the center mortise
- cut the "outside" "sloppy" mortise
- repeat on the other side of the center mortise

The 36 mortises, in two different widths took a little longer to do because it involved six foot long boards and there was some stock handling and rotating time to add to the time to cut the mortises. Total elapsed time for the fence boards' 36 mortises - maybe 15 minutes.

Total elapsed time to cut 72 mortises - under a half an hour! AND - only one OOPS!. This DOMINO tool is pretty amazing.

NOTE: Were these mortises to be done with a plunge router and mortising jig, even the Leight FMT, there would have been THREE TIMES more layout and AT LEAST TWICE AS MANY set ups. So instead of spending less than a half an hour, I'd have spent an hour and a half to two hours - minimum - to lay them out, set up the jig and cut all the mortises.

NOW are you starting to see how the DOMINO changes things?

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