Domino Question

[mr_hockey]

Have a questions about the Domino.

I have used a biscuit joiner for many years. Sometimes I will get a small bulge (or sometimes depression) on the surface over the biscuit.

I have seen articles on why it happens (moisture causes the swelling... sand it off... it drys and you have a depression...)

My question is... does the Domino exhibit the same type of behavior????

Thanks

 

[Les]

Since the domino is solid wood, it won't swell like a biscuit does. This is according to others who have used the domino. Makes sense. 8)

 

[clintholeman]

Since the domino is solid wood, it won't swell like a biscuit does. This is according to others who have used the domino. Makes sense. 8)

I have only used Domino on a few joints now, but I have noticed that the Domino tenons don't seem to swell like biscuits.  They behave like tenons do.

I'll have the near final pix of the bench I just made up tomorrow - it uses Domino joinery almost exclusively.  I love it!

 

[woodshopdemos]

The problem described isn’t because the biscuit swelled, but because the slot swelled. There was too much space between the biscuit slot and the inserted biscuit. This space was filled with glue, and this imparted moisture into the surrounding wood.

That being said, no, a Domino mortise should not suffer from the same problem because the mortise slot is a much tighter fit to the Domino tenon.

  While I agree with your final part of the answer, I cannot agree with your suggestion that the biscuit swelling (a given) has not caused slight bulging of the wood. I just googled "biscuit swell wood joint" and there is a lot being said on this subject. More to the point, I have had the problem...period!

 

[mr_hockey]

The now defunct "Woodworking at Home" DVD mag did a controlled study on this and here's what I remember  ??? from the research...

The moisture from the glue (plus the slot plus the biscuit) creates a bulge in the wood within a day. If you sand the top piece at this point, you will get a depression as the wood drys and equalizes. They showed some of their tests and it was very noticeable with a gloss finish. They also measured the depression and it was measurable.

Their solution based on their research was to wait a couple of days for the wood to equalize before sanding the top. 

 

[woodshopdemos]

John,
If the problem was primarily due to the biscuit swelling, you would not have a perfect outline of a biscuit telegraphing to the surface. The wood fibers of the surrounding substrate would distort this more. If you still doubt this, soak a biscuit in water, wipe off any excess water, and then insert it into a slot (no glue, but you'll need a hammer). Immediately sand the surface of the wood before any moisture from the biscuit transfers to the substrate, and then examine the results in a few days. You may find a depression, but it will not precisely mimick the outline of the biscuit. The depression, if any, will be much more gradual and bowl shaped.

I am not saying that the biscuit swelling does not contribute to the problem, but it is not the primary problem. It is the excess glue sitting in the slot, and this will be absorbed into the substrate.

Oh, I almost forgot. Since expansion due to moisture is a ratio of the material thickness, the 4 mm thick biscuit does not change very much in thickness compared to the thickness of the substrate.

Rick, I appreciate the direct answer. I still doubt the findings...and I guess more importantly, does it matter? With biscuits that are made compressed, they have a chance of swelling the joint and causing some disfigurement of the final surface.  I do not see that happening with the Domino and definetly have not had any such occurrence.

 

[Tinker]

One of the reasons I have never been interrested in Bisquits is that I have read from several sources that the bisquits do swell.  In a cramped shop such as mine, that translates into problems with assembly as well as problems with swelling as have been mentioned above.  One of the very first comments I recall reading about the dominos was that they do not swell.  And that is one of the reasons for my interrest in the system.
Tinker

 

[woodshopdemos]

One of the reasons I have never been interrested in Bisquits is that I have read from several sources that the bisquits do swell.  In a cramped shop such as mine, that translates into problems with assembly as well as problems with swelling as have been mentioned above.  One of the very first comments I recall reading about the dominos was that they do not swell.  And that is one of the reasons for my interrest in the system.
Tinker

Tinker,
  I think you are right on.

 

[Ned]

Matthew,

I've moved my joke to OT: OFF-TOPIC > General Chat & Random Ideas > How Small Is Your Shop?

How about moving HowardH's contribution as well?

Ned

 

[ohkipp]

Like john i have also had some telegraphing when using bisquits. i have limited my use of bisquits to only table tops and only for alignment. Now the kicker. I no longer glue in my bisquits but insert them dry. I have been doing this for a little over five years and have never had a failure.
Since my use is only for alignment, and the glues today are so good i feel confident of good results. I have on only a few times used CA glue if i thought there was a little to much slop, but then only a drop. Hope this adds to the confusion guys.....