Basically echoing Luigi he this is the order of operation that you want
to use:

1. Crosscut to 84.5" (smaller piece are easier to handle and require less
stock removal to true up).
2. Face joint (one flat face)
3. Edge joint (another flat face at 90 degrees and get rid of that 2x4
radius edge)
4. Rip to 3 - 1/8 (two edges parallel)
5. Thickness plane individual boards... there is not reason to make them all
the same thickness, take off as much material as you have to (to make the
surface flat) but no more
5.5. Make dog hole dados now if you want them.
6. Glue up 4 subassemblies about 7" x 3". I think that this will be about
as much as you want to try to manipulate. Smaller if you must, bigger if you
dare.
7. Run the subassemblies back through the planer to clean up the joints
8. Run both "edges" of the subassemblies through the jointer just to make
sure you still have a square edge. If you don't, your final glue-up to the
top will have a big honk'n cup that will take a long time to remove with a
hand plane
9. Glue together your subs
10. "touch up" with a hand plane :-). I smile because when I did this on a
nearly similar-sized maple top I "declared victory" after 4 hours.

BTW this will yield a roughly 3" thick top. More is better. Starting with
2x4's you would simply be throwing it away otherwise.

I hope that jointer is a not a benchtop.... pieces of this length and subs
of that weight kind of require a floor model. Also 84" is a pretty long
bench. IME it is considerably easier to true up 6' stock than 7' stock. That
is the difficulty/waste associated with truing stock increases
exponentially, not proportionally with length. Scaling back the length a bit
*will* make your life easier.

-Steve

"Luigi Zanasi" wrote in message
...
On 20 Oct 2005 13:07:42 -0700, scribbled:

Hi guys,
I am hoping to build a 7ft laminated workbench out of 2x4 douglas fir
studs (face-glued), the type you get at home improvement stores (maple
is too expensive and slippery). I bought 25 KD studs that came closest
to being quartersawn (along the 3.5" dimension), and let them
stabilize. (They have knots, but I can live with them if they are
under the surface).
The question is: how to go about dimensioning and surfacing them.
(I read posts dating to 1998, but few mention the surfacing problem).
They are so skinny that they are hard to keep stable on any machine.
Any kind of warping is hard to deal with to begin with. I have a table
saw, bandsaw, 6-inch jointer, and portable planer, all of which have
seen little use (I work mostly with hand tools).
The finished size of the workbench will be about 84 x 28 x 2.

I made mine out of 2X6 doug fir ripped in half.

First step is to get one flat face. That's what a jointer is for. If
they wobble too much on the jointer table, take off the high spots
with a hand plane. Alternatively, you could flatten using the planer
if you made a cradle, and support the wobbly pieces wood with shims.
Take light cuts.

Then through the planer to flatten the other face. Table saw should
work to remove the rounded corners and to straighten if they're not
too bowed. If you want square dogholes, you could cut dadoes with the
table saw on three of the 2X4s (assuming you want three rows of
dogholes.

Then glue up. I used pipe clamps and battens across the width held
with F-clamps to keep the top more or less aligned. You could also use
biscuits. Then flatten with hand planes as the glue-up will probably
be too big for the planer. Alternatively, do three glue-ups, flatten
each in the planer, and then glue the three together.



Luigi
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