DF 700 Domino Joiner Quality Issue. How bad is bad enough?

[CCWoodcraft]

Not a mechanical engineer so this is just a guess.

With that answer…you could become an honorary ME.  [big grin]

Too late [tongue] I'm already an engineer, if industrial engineering counts.

 

[ChuckM]

Snip.
The issue is the horizontal axis of the cutter is out of alignment with the entire fence assemble including the base.  While the amount may not seem like much, if using exposed tenons the skew is definitely visible.  The skew can also be fixed by using a shim.

Snip.

That's more than a 0.1mm problem.

 

[semenza]

Is it one millimeter or point one millimeter?

Seth

 

[escapegoat]

I sometimes get slanted mortises with my 700, but never with my 500. My guess is that the dynamics of drilling into wood with a large bit torques the cutter into a climb. I find that a slower plunge lessens the slant effect. Not a mechanical engineer so this is just a guess.

I don't own a Domino - do the cutters rotate in the same direction, or is one clockwise and the other counterclockwise? I believe the former would result in a net torque around the center of the slot.

EDIT: Duh, Dominos only have a single cutter.

 

[Cheese]

There is only one cutter.

 

[Birdhunter]

As to two cutters, I use a Mafell doweling machine that uses two cutters. They both turn in the same direction and the holes have always been perfectly aligned.

 

[ChuckM]

Snip.
I sent the tool into Festool repair and they sent it back with the attached samples demonstrating the problem and no note.  Snip.

I missed this part.

I suppose your machine is still under warranty. But whether you paid to get the fix done or not, that treatment was not customer-oriented. Not every user is technically oriented, and the technician had a responsibility and duty to explain what had been fixed or not been fixed because there was nothing to fix. If the technician who handled your fix was following the standard departmental procedures (of not providing any feedback after a fix), the procedures need to be revisited and improved.

 

[Lincoln]

Is it one millimeter or point one millimeter?

Seth

I was thinking the same, but the sample pieces in the above photos show .1mm difference, not 1mm.

 

[tsmi243]

Snip.
The issue is the horizontal axis of the cutter is out of alignment with the entire fence assemble including the base.  While the amount may not seem like much, if using exposed tenons the skew is definitely visible.  The skew can also be fixed by using a shim.

Snip.

That's more than a 0.1mm problem.

I think this is the crux of the issue.  As measured, that's a fantastic tolerance.  As described, it's not good at all.  These can't both be true.  And calipers on softwood isn't a great matchup, so I'm not sure I'd trust the measurements. 

What's a better test?  Maybe cut two mortises, about 6" apart, insert dominoes, and then set a straightedge on top, spanning the two.  Zoom in on the dominoes, and see what kind of angle is visible. 

Then, see if that angle is the same on each one.  If not, you've got technique problems to sort out.