[SJB]

Rewriting my answer below. I had replied to Rick's comment before I realized there were other answers here. Thanks to all for your replies - it seems my question wasn't well written in that I didn't provide enough detail. Rewriting below.

 

[SJB]

Hi all, let me rewrite this as it wasn't at all clear in my first go-around.

As you can see in these two photos, the cost of lumber is quite steep here; a (fir) 7.75' long 2x4 is US $16.69:

What I'd like to do is sandwich a few 200 x 60 x 1.8 cm boards (.75") to make a board that is 1.5" that I can then cut lengthwise into laminate 2x4's and 2x6's.

As you can see from the stack, they are more or less flat. Some bowing occurs when you remove them from the stack but I'll cherry pick the best ones I can. I want to more or less glue them as they lay like this in the pile:

Stacked like that with 200# of water, good enough?

 

[SJB]

You're not going to like my answer. Here's a glue-up that was only 10 inches wide by 16 inches long, and I still didn't have enough force/pressure to do it properly. As I turned this on the lathe, I found I still had a visible glue line closer to the center in one area.

When you do the math, you see how difficult the problem can be with a face-to-face glue-up. The amount of force that you need is equal to the desired pressure times the surface area of the joint. So in your case, it would be 72 inches times 24 inches (1728 square inches) times 14 psi = 24,192 pounds of force. And that's only for atmospheric pressure. Normally, I recommend 100psi clamping pressure, which would result in 172,800 pounds of force.

To the contrary Rick, I do like your answer. You make a good point and I am not sure that water bottles is going to get a consistent glue squeeze out across the length of every board in the stack. If I am to cut these into 2x4's and 2x6's, then I need 100% (not even 99%) glue coverage and bonding. I don't want one of my laminant 2x4's to separate later.

If this run is successful, I plan to repeat this going forward because it is the only way I can afford 2x4's and 2x6's with the lumber prices here. Two of the 2m x 60cm x 1.8cm sheets is ~ 13.50 Euros, so 26 Euros for the pair. I can cut these into 6 boards that are close in dimensions to a 2x4. The price for me would drop from Euro 14.25 to 4.33 (26 Euros / 6 boards).

Looking at your photo and the price of pipe clamps here, your rig would cost me (not including pipes) about 600 Euros (USD $702). While your rig sure looks stout, it isn't quite in my budget this month :wink:

I could run (underneath) a row of perpendicular 4x4's with another row on top, the two tied together a 10cm (.40") bolt (threaded rod), some washers, and wing-nuts.

I made a rough sketch of my clamp idea:

I can buy a garden 4x4" (9x9cm, 2.4 meters long for EUR 13.50) and get 3 per board. I would need 2 pieces for each "clamp" for a wood cost of 9 Euros and hardware of about 2 Euros (1 meter long 10mm threaded rod is .95). So, about 11 Euros per clamp. If spaced 12" apart, I would need about 6 of these (66 Euros), if spaced every 8" then 10 of them (110 Euros). Certainly beats 600+ Euros and I think would get the job done.

I appreciate everyone's input - thanks to all.

 

[SJB]

SJB, I'm not sure what you will be doing with this wood. The lengths seem short for building lumber, and the cross sections seem heavy for furniture or cabinet making.

The 44mm lumber looks like ok--ok but not great--framing fir or whitewood. The edge glued 18mm wood looks like some plantation grown hard pine. There's a lot of pith in the end grain. These were small trees. I would not assume these are equal for strength or stiffness if you have a highly stressed structural application in mind.

JohnGi, bingo, it is pine (pino). With it I'm just going to build some bunk-beds. Not sure I'll be purchasing a vacuum bag before Christmas :wink: Honestly, that's the first time I've ever seen that. But, as someone's sleep will be relying on the glue joint, I'll take Rick's advice and I suppose I'll be using clamps rather than water bottles.

I'll be sure to post some pics for the clamps and the build.