How to lay down a series of slots with the domino?

[Toller]

I want to extend a 45" plywood panel with a 1.5" hardwood strip, using 8 5x30mm dominos to secure them together.

I originally envisioned running a series of indexed slots down the plywood edge, and a series of wider slots down the hardwood addition.  But if I use wider slots on one side, they will gradually migrate up because I will be indexing from a wider position.  Since each movement is cumulative, it will be considerably off by the end.

I see three solutions.
1) Use a slightly smaller index amount for the wider slots.  (how much smaller?)
2) Use wider slots on both sides so they will move the same way. (won't that sacrifice some strength?)
3) Forget the indexing on the wider side.  Mark the centers and cut the slots to the mark.
4) Cut narrow slots on both sides; then widen the slots on one side using the narrow slots for indexing.

#1 seems best to me.  Whatcha think?  Any other ideas?

 

[bruegf]

I've found it to be far easier to lay the hardwood edge against the panel and use a square to mark center lines on both pieces at the same time.  I cut a narrow mortise in both the panel and the hardwood on one end and then use a medium slot width for all the other mortises.  The medium width mortises are forgiving of any small alignment errors and make it far easier to insert the dominos when gluing.

Fred

 

[greg mann]

What Fred said except that I use a narrow setting for all the cuts on one component and the 2nd setting for all the slots on the other component except for the first one like Fred also.

 

[bruegf]

Greg,

I've used that technique and it works every bit as well.  The only reason I've started using the medium width mortise is because it's a tiny bit easier to get the dominos in the slots when gluing the two pieces together.  I tend to be a bit slow, so anything that shaves a few seconds helps to keep the glue from starting to dry before I get the pieces assembled.

Fred

 

[Michael Kellough]

Greg,

I've used that technique and it works every bit as well.   The only reason I've started using the medium width mortise is because it's a tiny bit easier to get the dominos in the slots when gluing the two pieces together.  I tend to be a bit slow, so anything that shaves a few seconds helps to keep the glue from starting to dry before I get the pieces assembled.

Fred

With Gregg's method, complete the gluing in of the dominos in the narrow mortises first, before applying glue to the joint.

 

[greg mann]

You are correct, that is what I do Michael. You can take your time on the first component and concentrate only on the dominos.

 

[Dongar]

Hi Tollet
You have to make both set of mortises wider after the first one in order to keep the alinghment.If you want to keep all the slots in the first board narrow and only the first one tight in the second board you have to reset the spacing to be 1/2 of the difference of the slot width less, after you cut the first slot at the wider setting. I think the difference between the tight and middle setting is 6 mm. So you would move the cross stop 3 mm smaller after you cut your first wide slot.I hope this makes sense if not let me know.
Don