help: is my domino misaligning placement in 45 degree miter?

[Justin Michael]

Hopefully someone can explain what's going on.  I set the fence to 45 degrees, and set the scale to 11mm (not the stop block).  My understanding is the scale sets the distance from the fence to the centerline of the bit.  I cut some 6mm mortises and found that they were actually 14mm on center.

It's important that these mortises be accurately placed as i am butting the miter to the face of another board and i need the edge of the miter to line up exactly with the edge of the other board.  if they are off by 3mm, the miter comes up short of the edge of the other board.

I've read both supplemental manuals but they were silent on this issue.  I think it has to do with where the fence pivot is located, but i'm not sure. Any insight would be appreciated.

 

[Rick Christopherson]

Because the pivot point is inside the fence face, the distance will be greater with a bevel on the fence.

 

[tjbnwi]

I believe you will have to do a test cut to be accurate. Because the height changes, you do not get single point entry.

Tom

Rick types faster than I do.

 

[Trosey]

I think it has to do with where the fence pivot is located.

You are correct. The pivot is above the cutter and behind the face. You should be referencing off the obtuse angle of both pieces and they should fit. I would want the mortise toward the inside so that the cutter would not blow thru the outside.

HTH

 

[AIPDX]

Justin Michael, I did not have an occasion to use my Domino with anything other than straight cuts, but your question reminds me about a topic which was raised by Gary Katz during his demonstration at a JLC show in Portland several months ago. He and his assistant were building a mantel for a fireplace and were joining two boards with edges cut at 45 degree angle with a Domino. He explained that there is trick to making mortises at a required offset from the edge which he understood hard way, and finally figured it out only when he attended a training at a Festool facility. He thought it was so important that he repeated his explanation twice. I cannot say that I fully understood every detail because I did not experiment with it on my own after the show and it was a little hard to see from where I was sitting, but I do remember the general message. The idea was that one has to set up the offset BEFORE changing the fence angle to 45 degrees. If one does it the other way around (which may seem a logical thing to do), the position of the cut will be off. Based on your description, it might be the problem which you are dealing with.

Sorry that I neither can provide more details nor offer a sufficiently clear explanation, but it might be the idea for you to experiment with.