Queation about cauls

[Ray Newman]

Colleagues: am fabricating a small book shelf -- 72" H x 15" W x 12" Deep from 3/4" plyw'd.

Dadoes will house the shelves and a dado and tongue joint will fit the top and bottom to the sides.

A Fellow Woodworker suggested making 6' long  2x4" cauls to close it all during the glue up. He suggested first rip the 2x4 to uniform width, then place on edge with a playing card (or two) in the center of the cauls and apply pressure to close it all up.

'Nevva' utilized cauls before. My question is: will 6' 2x4 placed on edge bend enough to apply enough pressure to close it all up?

Thanks in advance for any information.

[Cooler]

I've built many shelf units from plywood.  I just clamp with two bar clamps on each shelf (one on the front and one on the rear).  Four shelves will require 8 clamps.  Plus one long one if you need to square things up.

[giradman]

I've built many shelf units from plywood.  I just clamp with two bar clamps on each shelf (one on the front and one on the rear).  Four shelves will require 8 clamps.  Plus one long one if you need to square things up.

@ Ray - agree w/ the above - I've made a lot of bookcases over the decades (typically I have one fixed shelf to help hold the carcass together and then use a hole jig to make adjustable shelves) - but I use just clamps for that purpose and of course make sure that the diagonals match.

Now, I own a pair of commercial cauls (from Lee Valley) - the 3 ft ones shown below - notice the degree of the central bow - doubt that a playing card or two will do much - usually 'homemade' cauls are made from a hardwood w/ the bow planed from the center to both ends, taking off more wood as the ends are approached.  I've used the cauls when gluing up a panel to keep the joints aligned, saving on surface prep later.    Dave

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[Ray Newman]

Gent: thanks for the information as I thought the advice given sounded too good to be true! Just need to find and dig out more clamps from the shop storage corner. Again, thanks.

[Cooler]

Gent: thanks for the information as I thought the advice given sounded too good to be true! Just need to find and dig out more clamps from the shop storage corner. Again, thanks.

You can't have too many clamps.


I did see Norm Abrams (on TV) first clamp, then pin the shelves.  He placed the pins (nail gun) at an angle up just under the shelf so it passed through the corner of the shelf and into the dado.  Then he could remove the clamp.  I would do this if there were not enough clamps.

[mike4244]

Colleagues: am fabricating a small book shelf -- 72" H x 15" W x 12" Deep from 3/4" plyw'd.

Dadoes will house the shelves and a dado and tongue joint will fit the top and bottom to the sides.

A Fellow Woodworker suggested making 6' long  2x4" cauls to close it all during the glue up. He suggested first rip the 2x4 to uniform width, then place on edge with a playing card (or two) in the center of the cauls and apply pressure to close it all up.

'Nevva' utilized cauls before. My question is: will 6' 2x4 placed on edge bend enough to apply enough pressure to close it all up?

Thanks in advance for any information.

There are several ways to make cauls. 2 x 4 's that are slightly bent to begin with can be used s a caul. Not hard to find, straight lumber, that's hard to find.
If you want to make cauls there are ways to do this depending on your tools and skill. 
In your case I would rip a 2 x 6 in half length wise. You will wind up with about 2-5/8" + or -.
Cut to 76" or more. Find center e.g. 38" , divide this in half 19" ,repeat 9-1/2" .Mark these dimensions on each side of center line and connect the dots. If you have a bandsaw  or a decent saber saw then use these tools to saw your cauls. You can also hand plane the connecting dots and sand any high spots. 
When done, Screw a scrap on each end so the dimension is 1/4" longer than the glue up. This aids in clamping the caul. I generally clamp the middle first. Then each end and remove the middle clamp.
2 x 3 's are better for cauls than 2 x4 's. 2 x 4 's won't bend well because of the width. Soft wood cauls are fine. You can wax the areas that might get glue on them if necessary. 

mike

[AHill]

If your shelf is only 12" deep, cauls are not required.  Just clamp both ends like shown in the Norm picture.  If you have k-body or parallel clamps, they'll work even better.