Snipped per FAQ..


> On 1 Aug 2015, at 03:20, Mark Pfeifer  wrote:
> 
> 
> Hit the glue, 12 clamps to an 8’ slab, they looked sweet clamped up, like one
big slab. Stuck around for a while tweaking a screw here and there until nothing
was seeping, nothing was popping. Big stable slabs. Yummy.
> 
> Shut down the shop, went to bed, couldn’t wait to get up this morning,
unclamp, and do a little smoothing with the #6, my favorite Stanley.
> 
> To my horror, despite being COMPLETELY CLAMPED, these sob’s managed to gap on
me. I swear someone put a hex on it . . . there is no rational explanation. It
was perfect when I shut off the lights. When I cut one end of the slab for
square, instead of one nice loaf of wood, each of the 2x4’s fell off in sections
as I cut. Needless to say I’m really bummed out. I did it all “the right way” .
. . . .
> 
> For the bottom of the slabs I cheated and slathered more glue into the gaps
and smoothed it all off with a hunk of thin plywood. For the tops . . . . I
don’t know. Part of me wants to plane 1/4” off and see if maybe they just gapped
on top . . . . maybe the glue dried funny? Maybe if I plane 1/4” off the top my
beautiful unitary monolithic slab is still there?


My ‘travelling bench’  is made from 2x4 material, It does its job.  I should
have written about it maybe - the top has stayed ‘stable enough’ - way way more
so than the slab of english air dried beech I bought in the first place ( to
reference another thread)

Back t the plot though. I suspect that your glueing is your problem.

First - preparing to a glass smooth finish would be a bad thing for a glue up.
Hows the glue going to hold if there is no access to the fibres?  After getting
that satisfying finish, you need to then destroy it with a sheet of 120 grit
abrasive - keeping everything square, and not destroying the corners.
Then you need to arrange the joint for glueing.  for something like this I would
be very very tempted to use stub dowels to align the joints. with your sharp
jennings bit, a pair of random holes, on at each end, in the centre of the
board.  Then with your dowel aligning pins, press the opposing face to mark it,
bore the matching sockets, then make up the dowels and assemble dry to check
that everything mates up. you could plane the surface closer to final finish if
it were necessary.

Now disassemble and apply the glue,
You are aiming for an even glue line, 20 - 40 thou thick.  I sued to just spread
some glue from the bottle and assume that it would spread out as I cramped the
joint.  I don’t do that anymore.  I use some form of spreader, and get an even
spread over all surfaces.  For e really important job, that would mean coating
both surfaces, with the glue well scrubbed in to the face of each.
Now, when you bring the faces together, they will be aligned, and stay that way
without effort, whilst you tighten the clamps you arranged earlier when dry
fitting.

You should have little squeeze out, if your surfaces mate, and your spreading
was even, then you want to see the glue appearing, evenly, at the edge of every
joint.
You do NOT want to keep tightening until the joint has given up all of its glue
load.  Again, the even spread, and the knowledge that your planing has ensured
the faces mate well will leave you confident enough to stop, and let the glue do
its thing.

Incidentally, I now use Titebond almost exclusively.  Cascamite is the only
other go-to glue for me, Titebond comes in grades though.  Get the good stuff.
The ones rated for waterproof use, or the one rated for below water.  Cascamite
is a different animal.


As for fixing your present bench.  adding a surface of plywood would be a really
good thing - benches that do real work are often made with ply, it’s a good
surface, it’s ‘disposable’ so adding nailed stops or screwed on jigs is OK.  You
don’t have to worry about damaging it.  paint, glue spots, anything can be
scraped off, and if you need to run in a couple of inch holed for a non standard
position for a bench stop you just do it.  When you replace it eventually, the
substructure may have holed, but they all vanish when your new top goes on.  A
coat of varnish and its new and lovely all over again.


It’s a bench - it’s a working tool, a building experience, not a dilettante YB
ornament.  No problem here..


Richard Wilson
Yorkshireman Galoot
in Northumberland.