Rub joints, conclusion

[James Pallas]

I gave the sample 12 hours or so to dry. I put it in a vise clamped a 1/4” piece of hard maple to even the load with even exposer at the vise and the maple. I applied pressure to the clamp handle the wood snapped above the glue line. I then lowered the piece in the vise and set the clamp close to the glue line. I tried this several times and the clamp slid down the piece without effecting the joint, and yes the clamp was tight. My opinion is that in the normal course of work a rub joint, if properly done is as good as a clamped joint in this usage.

[Andrew Seemann]

Hi, What kind of glue did you use? I typically associate a rub joint with hot hide glue, where the initial tack of the glue cooling/gelling holds the pieces together until the glue develops full strength the next day.

[James Pallas]

Hi, What kind of glue did you use? I typically associate a rub joint with hot hide glue, where the initial tack of the glue cooling/gelling holds the pieces together until the glue develops full strength the next day.

HHG works well. I have used PVA and liquid hide glue. PVA and HHG feel about the same to me. You can definitely feel it when it’s time to line it up and leave it. Liquid hide glue has a different feel to it. In this case it was PVA. When I used liquid hide glue I think the results were fine just a different feel.

[Jim Koepke]

Jim, Thanks for taking the time to test this method of jointing wood.

jtk

[James Pallas]

Jim, Thanks for taking the time to test this method of jointing wood.

jtk

Thanks Jim. I thought that this was a very widely used technique. I guess that’s not true. I’ve done it since I started learning as a kid about 60 years ago. I use it a lot especially on smaller tasks.

[steven c newman]

Often use a rubbed joint.....while building up panels for tops and such. Since I start with one board along the edge of the bench, and work my way up through 3 to 5 more boards...
June Project, Top glued up, good side.JPG
When I don't have the room to lay a panel flat....
June Project, bottom shelf glue-up.JPG
I still rub the next board until I feel it "stick" in place....

[Will Blick]

I have found this to be true as well....
and if your boards are jointed perfectly, you can sometimes get a perfect glue line, seamless with no clamps.
But I rarely get perfect jointed edges, specially when the boards are long....
clamps overcome these imperfections to create a seamless glue line with max holding force.
This demonstrates just how remarkably strong modern glues are.

For thinner boards, clamps may add some required strength, as there is less glue surface area.
the more space between the boards, the weaker the glue joint.
but when you test it with thicker boards, the glue is sooo overkill, it always prevails in the break test.

[Jim Matthews]

Thanks for mentioning this: it just got me out of a jam with the last of some panels that were not wide enough. Properly squared stock makes this dead simple.

[James Pallas]

Thanks for mentioning this: it just got me out of a jam with the last of some panels that were not wide enough. Properly squared stock makes this dead simple.

Happy that you were able to use it. I had never tried to test it myself. I always just used it when needed. After I posted the last photos I did more destructive testing. I drove a 1” chisel into face at the glue line. It went about 1/3 thru before it broke. Pieces of wood on both sides the glue line held fine.