DIYbanter - View Single Post - Jointing On A Router Table

-MIKE-

On 1/14/18 5:54 PM, wrote:
On Sun, 14 Jan 2018 16:28:13 -0600, -MIKE-
wrote:

On 1/14/18 4:03 PM, wrote:
On Sun, 14 Jan 2018 12:44:52 -0600, -MIKE-
wrote:

On 1/14/18 11:02 AM, Leon wrote:
My table saw leaves a very clean edge, but my router
table leaves a edge that is buttery smooth.

Not the best for a glue up.

I wondered about that as well. A really smooth surface
won't soak up the glue as well and you could squeeze out
too much when clamping.

There is a lot of back and forth on this. Typical
yellow/wood glue is not a good gap filler and works best with
a minimum of product in the joint. Tooth marks create gaps.
Additionally there is a lot of back and forth talk on
starving a joint by squeezing glue out of it. Glue starvation
as it is often called is when there is no or not enough glue
on the surface to begin with not because you had squeeze out.
You get squeeze out because there was too much glue in the
joint to begin with. If you don't get squeeze out you have
no indicator that the joint is tight. I have never had a
joint fail because of too much clamping pressure and causing
too much glue to squeeze out. Remember, a quality glue joint
line is one that is almost invisible.

Yeah, there are a lot of old wives' tales in woodworking and
those are three of them. Glue doesn't "bite" and holds
perfectly fine to "buttery smooth" surface.

Try it with glass.

Does the bottle state the product works on glass? Don't look, I'll
tell you. No, it doesn't.

No, it doesn't because it needs a mechanical connection to the
surface. That requires a texture, much as they tell you to rough up
gloss paint before repainting (after cure).

The glass comparison is totally irrelevant. The glue doesn't work
on many many things, but that in no way supports your "smooth
surface" theory.

No, it really isn't.

Paint isn't glue and not all "mechanical" connections are the same.
I don't think you truly understand how wood glue bonds.
In any case, I think we may closer to being on the same page than we
think.

I believe you are correct when you say a surface can be "too smooth."
When I was at a home show, some years back, I spoke at length to a
representative of Franklin Adhesives who was also a chemical engineer
who worked in adhesive development for years until retiring to be a rep
at these home shows.

It was another time that this subject had come up and I asked him about
it.
He said it was almost impossible to get a wood surface too smooth to
adhere well with glues, using most woodworking power tools. He did say
that the surface could be "burnished" to the point that would weaken the
joint somewhat, but it would still be strong enough for most glue
joints. He added that he knew of no woodworking power tools that would
yield this kind of surface.

He then when on to say, "If you are ever in doubt, all you have to do is
put a drop of water on the surface of the wood. If it soaks in, it's
fine. If it beads up and sits on the surface, then hit it with some 220
grit and glue it up."

--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
www.mikedrums.com