It's gotta be a cold day in hell right now
because I bought one of these dreadful
pocket hole jigs.
The reason I bought the pocket hole jig
is to test the strength of the joints.
And for that I built this screw jack,
it's on a bathroom scale and it's gonna
break joints like this one,
on my joint testing apparatus.
A drill turns the gear here on the screw jack,
which applies a slowly increasing force
measured by the bathroom scale,
and this camera records the force.
Pocket hole test. Sample number 1.
Pocket hole sample number 2.
So, this is the tricky part with the pocket holes.
We already see this joint opening up significantly here,
even though the scale is not even at 50 pounds.
So the joint really opens up even before it fails
at much less forces.
Let's see how far this one goes.
Pocket hole number 3.
Pocket hole 4.
105 pounds.
The problem with wood is it can really vary a lot,
which is why it's important to run many tests.
Next we'll try some dowel joints.
These are glued with type bond 3 and I gave them
2 days to dry.
Dowel joint number 1.
160 pounds. Dowel joint number 2.
160 again. Dowel joint number 3.
We're at 140. Next I'm gonna test
mortise and tenon joints.
I cut all the mortises on my slot mortiser,
and then I cut all the tenons on the Pantorouter.
I made a total of 9 mortise and tenon joints.
3 of them are glued with just the yellow glue,
3 of them with type bond 3,
and 3 of them with epoxy.
Yellow glue sample number 1.
Whoa! Yellow glue sample number 2.
235.
Yellow glue sample number 3.
185 pounds.
Type bond 3 sample number 1.
190. Type bond 3 sample 2.
180. Type bond 3 sample number 3.
230. Epoxy sample number 1.
270. Epoxy sample number 2.
225. Epoxy sample number 3.
215. So the pocket hole joints
really didn't fare very well, even against dowel joints.
And for mortise and tenon joints,
they were an average easily twice as strong
as the pocket hole joints.
What's surprising is in the past I've found
that type bond 3 to be slightly stronger
than this yellow glue but with this wood
the yellow glue did slightly better.
And the strongest was the epoxy
but it's also the most annoying to deal with.