Domino cutter motion explained?

[ChiknNutz]

Being a mechanical engineer, I am intrigued by how this machine works.  As I don't yet own one, I am wondering if someone can explain how the cutter moves so that it can create a mortise with parallel sides and a flat bottom (assuming it actually does this).  I can only find a couple videos showing the cutter motion itself and they don't really show how it achieves this.  I see that the bit pivots on an axis, but it must also move side to side in some fashion to make the sides parallel and the flat bottom...right?

 

[Dick Mahany]

The plunging action is what yields the parallel sides.  True the cutter pivots, however as it is plunged to the desired depth, the widest point of the arc is simply carried through the depth from the beginning of the cut until it reaches the bottom thereby creating straight sides via a pivoting bit ..........magic  [smile].

 

[ChiknNutz]

Isn't the bottom truly flat too though?  That is the feature I can't see how the pivoting bit produces a flat bottom at the end of the plunge.

 

[Dick Mahany]

Isn't the bottom truly flat too though?  That is the feature I can't see how the pivoting bit produces a flat bottom at the end of the plunge.

I don't think so, however the curvature is so small that it is essentially negligible.  For instance on my DF500, the radius of curvature on the pivot is approx 115mm.  When set to cut the minimum domino width of between 16mm and 22mm, depending on domino tenon size, the curvature at the bottom of the cut will be on the order of 0.3mm to 0.5mm.  Probably helps trap some of the excess glue also.

It would be fun to do a high speed video of just that action through a piece of clear poly-carbonate.  Somebody out there must have the right gear to do this.

 

[ChiknNutz]

Ya it really doesn't matter all that much if the bottom is truly flat, just that the tenons arrive at the appropriate depth, which it clearly does.  I have used one a few years ago on a project, but never looked at the bottom of the mortise that close but what I recall was it *seemed* flat which I thought was marvelous if so given the mechanics of it all.

I poked around quite a bit all over the web and couldn't find any suitable videos, pictures, mortise cross-sections or detailed explanations.  The closest I found was a video a guy did that commonly takes stuff apart to show how it works.  This one showed the oscillation, but thought there might be some other feature he didn't show.  Looks like it just oscillates but the arc is large enough to not matter.  Anyway, thanks.

 

[Dick Mahany]

Yes that tool is truly a wonderful piece of engineering, and an absolute game changer.  Be careful though, they can become addictive and habit forming and you'll be continuously eyeing things to make mortises in.  I keep finding new uses for my DF500 and thankfully I don't have the need for the larger version (yet  [wink] ).

 

[Jiggy Joiner]

Dick has described pretty much how it works, the bottom of the cut is concave IIRC, not that it matters much as I guess it fills with excess glue.

 

[Stone Message]

Hi Everyone

Back in 2017 I was privileged to be invited to Festool HQ for a bloggers event. Whilst there Frank Jaksch used a DF500 to cut into a clear Perspex block.

Here is the video clip that I made:


Peter

 

[Dick Mahany]

Hi Everyone

Back in 2017 I was privileged to be invited to Festool HQ for a bloggers event. Whilst there Frank Jaksch used a DF500 to cut into a clear Perspex block.

Here is the video clip that I made:


Peter

Thank you Peter ! [thumbs up]

 

[ChiknNutz]

Perfect!